Are you running hot?
This whole process started when I read an interesting article by Pat Lockyer some time ago. He discovered that there was a restriction on the driver’s side of the timing case cover caused by the distributor shaft running through the water jacket. So I decided to measure the temperatures on each side of the engine with some temperature probes. Thanks to Bill Ebzery we managed to get our hands on such a device but with no running engine of our own to test it on we waited for an event at our place so that we had the two vital ingredients. The first was Bill Ebzery to run the device and secondly the most important was Sue with her Jupiter so we had a car to test. Firstly we had to rig up the car with the temperature probes as shown by the pictures at the end of this article.
We then started the car and waited a while for it to warm up a little. The following results were taken with the car in neutral and revved between 2000 to 3000rpm. The ambient air temp was also measured at a lovely 23oc. One interesting note was that while the water pump temperature measured 65oc the cars temperature gauge read a much higher temperature which fluctuated between 75oc and 81oc. Looks like Bill has another job to do when he gets home.
Time Interval between readings (mins)..06..08..10..12..14
Passenger timing case ..........................42..46..48..49..51
Passenger water transfer.......................55..62..63..63..64
Driver’s timing case................................56..65..65..66..68
Driver’s water transfer...........................58..69..71..73..76
Water pump outlet..................................60..70..64..65..65
From the chart above we can see that there is a substantial temperature problem on the driver’s side of the car which is the side with the restriction, at the worst there is a 19oc difference between the two sides of the engine. We must now ask ourselves several questions. Does this affect the car’s running? How do we go about fixing the problem? Is it worth fixing the problem? These cars have run for 50 years and the majority have survived intact. Although I can’t answer all the questions above I do have a theory about how it affect the cars running. For an example let’s assume you run absolutely no coolant in your engine, when the gauge on the dashboard reads 90oc you think that’s ok I’m not boiling yet, however while the passengers side of the car may be around 90oc the drivers side is 19oc higher at 109oc and has turned into steam which is not very good for cooling.
Granted nowadays with the addition of coolant and the 4 PSI of system pressure the cars won’t boil till around 120oc however the problem is just delayed not cured. Also who knows what other affects the temperature difference may have on the engine? Hopefully this article has given you a little more insight into our beloved Jowetts. Whether you’re young or old its interesting learning about what makes our unique little cars tick. Finally, thanks to Bill Ebzery for the use of the equipment used in this experiment and his expertise in running it and Sue for being kind enough to lend us her baby to be poked and prodded.
By David Hood
Lobsided Jowett not balanced at all.
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So that makes me think I had better check the temperatures on my Javelin and discover where this heat is really coming from or indeed if the gauge is 'up the swanny'
Now where do i get a digital contact thermometer from?
Took Javelin for a 30 mile run on Saturday with 4 people in the car up some small hills. It did not over heat but it was 10 deg C outside. So will have another go this weekend and give it a thrash up the motorway.
I may fit the same arrangement on the Jup with temp sensors in each head. I did not notice such a difference with them; but that could be calibration. It would be interesting to do this on a selection of Jups and Javelins.
Someone with a thermo dynamics degree (me) who can actually remember any of it (not me) perhaps can deduce the difference in flow in each side. Pat's solution pictured in the JowettGallery may not be the only reason. It could be flow in the head as they are not symettrical when turned around as they are.
The fact that the gauge reads high may actually be part of the design, compensating for the drop in temperature from head to header tank. But that would be unlikely as we generally test them in a boiling water, don't we?
Now where do i get a digital contact thermometer from?
Took Javelin for a 30 mile run on Saturday with 4 people in the car up some small hills. It did not over heat but it was 10 deg C outside. So will have another go this weekend and give it a thrash up the motorway.
I may fit the same arrangement on the Jup with temp sensors in each head. I did not notice such a difference with them; but that could be calibration. It would be interesting to do this on a selection of Jups and Javelins.
Someone with a thermo dynamics degree (me) who can actually remember any of it (not me) perhaps can deduce the difference in flow in each side. Pat's solution pictured in the JowettGallery may not be the only reason. It could be flow in the head as they are not symettrical when turned around as they are.
The fact that the gauge reads high may actually be part of the design, compensating for the drop in temperature from head to header tank. But that would be unlikely as we generally test them in a boiling water, don't we?
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Alastair Gregg
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Temperature measurement
A fairly easy and cheap way of measuring temperatures without very specialist or expensive equipment would be this:-
http://www.maplin.co.uk/Module.aspx?ModuleNo=223009
I have something similar. and as long as the laser hits at the same point on each engine then the temperature is measured accurate to around + or - 1%. Those with degrees in thermodynamics may shudder at the inaccuracy of it all, but at under £35.00 the price is right. If a standard test similar to the above is devised we could then rate the thermal efficiency of any engine based on the revs over time and per measured point. Someone would need to collate the data though, before it became helpful. Once base lines were set then modifications like Pats could be assessed and an informed decision taken as to whether to implement them.
Gosh I almost sound efficient here
http://www.maplin.co.uk/Module.aspx?ModuleNo=223009
I have something similar. and as long as the laser hits at the same point on each engine then the temperature is measured accurate to around + or - 1%. Those with degrees in thermodynamics may shudder at the inaccuracy of it all, but at under £35.00 the price is right. If a standard test similar to the above is devised we could then rate the thermal efficiency of any engine based on the revs over time and per measured point. Someone would need to collate the data though, before it became helpful. Once base lines were set then modifications like Pats could be assessed and an informed decision taken as to whether to implement them.
Gosh I almost sound efficient here
Compliments of the Season,
Alastair Gregg
Alastair Gregg
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Mike Allfrey
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G'dday From The Still Burning South!
I saw mention above of sensors mounted in the water transfers. Would these be modern electric type gauge sets?
I have a theory about modern temperature gauges. I believe they indicate 'Normal' over a very wide temperature range.
I had an experience with a Ford Falcon some years ago when the radiator cap let go while on a long country run on a very hot night♦. The temperature gauge indicated 'Normal' while a passenger remarked that something smelt hot. As the gauge was being watched, the indicator needle swept rapidly round to beyond the red zone and stayed there.
After stopping, it was soon seen that the normally silver painted rocker cover was a sort of brown colour, the plug leads had been fried and the porcelain insulators on the sparking plugs were a grey colour, instead of white.
The elctric gauge had indicated all was normal while this was happening.
In addition to that, my current Rover 75 V6 and the Jaguar XJ-S V12 that I had for a while, stubbornly show 'Normal' at all times once the engine has warmed fully. Both of those cars have been driven long distances in 43 degree (in shade) heat. The Rover's gauge seems to be programmed to indicate normal, no matter what! I knew the Jag was hot at times just by the smell of the engine and the creaking as it cooled down. Yet all was apparently 'Normal'.
Consequently, I do not trust electric type automotive temperature gauges at all. In addition to that, we need to consider that nearly all Jowett temperature gauges are over sixty years old - but I have faith in them.
The smoke from the fires hanging around here is awful this morning - looks like somewhere else is overheating too.
All the best,
Mike A.
I saw mention above of sensors mounted in the water transfers. Would these be modern electric type gauge sets?
I have a theory about modern temperature gauges. I believe they indicate 'Normal' over a very wide temperature range.
I had an experience with a Ford Falcon some years ago when the radiator cap let go while on a long country run on a very hot night♦. The temperature gauge indicated 'Normal' while a passenger remarked that something smelt hot. As the gauge was being watched, the indicator needle swept rapidly round to beyond the red zone and stayed there.
After stopping, it was soon seen that the normally silver painted rocker cover was a sort of brown colour, the plug leads had been fried and the porcelain insulators on the sparking plugs were a grey colour, instead of white.
The elctric gauge had indicated all was normal while this was happening.
In addition to that, my current Rover 75 V6 and the Jaguar XJ-S V12 that I had for a while, stubbornly show 'Normal' at all times once the engine has warmed fully. Both of those cars have been driven long distances in 43 degree (in shade) heat. The Rover's gauge seems to be programmed to indicate normal, no matter what! I knew the Jag was hot at times just by the smell of the engine and the creaking as it cooled down. Yet all was apparently 'Normal'.
Consequently, I do not trust electric type automotive temperature gauges at all. In addition to that, we need to consider that nearly all Jowett temperature gauges are over sixty years old - but I have faith in them.
The smoke from the fires hanging around here is awful this morning - looks like somewhere else is overheating too.
All the best,
Mike A.
E0 SA 42R; Rover 75
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Well after talking with Leo Bolter on Skype I decided to trawl the net and bought a Hilka temp sensor on the web for £20 +postage. Arrived today, tested it on my blood and Jenny's gammy knee (it acccurately found the inflamation to within an inch of the pain through her jeans) and was happy with its accuracy so promptly went down the garage and fired up the Javelin. If it can pinpoint a human condition perhaps it could for a Jowett.
I started off measuring in various places as the car warmed up with about 1700 rpm adjusted on the throttle screws.
I will give the figures as I read them but please bear in mind the gauge is affected by reflectivity of the aluminium or rubber or matt black paint. I reckon a possible 4deg F variation. Obviously I tried to pinpoint the same spot with the laser each time but the distance from the surface also affects the instruments field of view and hence temp reading.
The warm up run was measured in Fahrenheit and shows seven sets of readings from 9 areas, each set taking about a minute to do, so I was measuring continuously. Time ran from top to bottom and then left to right.
The diagnosis run that follows ,shown in Centigrade, has same 9 measuring points with the engine up to temperature. The electric fan kept switching on its thermostat which was set at 75C. The run was done at normal idle of 800 rpm.
Header tank....................67 84 117 138 160 185 187--86 72
Left rad outlet..................69 86 120 142 159 181 186--77 74
Right rad outlet................69 86 116 136 162 157 186--74 70
Left Water transfer...........82 93 128 151 176 190 196--69 72
Right Water transfer.........89 86 116 133 146 152 169--54 53Why
Top timing cover..............75 85 116 131 147 163 161--70 64
Water pump out...............76 91 117 131 148 161 160--67 66
Left head next to 2 spark..92 154 141 158 184 189 xx--72? 85
Right head next to 1 spark98 116 138 157 181 xx xx ---79? 69
Why? I do not know why this consistently read so low as the head seems to be cooling the water!!!
the ? indicate I suspect they should be transposed. Will recheck!
Note the considerable differences between left and right water transfers.
Next I measured the temperatures as close to the spark plugs as possible
and also the exhaust manifold temp at the outlet of each cylinder
No 1...87 130
No 2..90 170
No 3..85 153
No 4..79 153
Oil sump 65
Oil Filter 74
Oil cooler in 67
Oil cooler out 66
I started off measuring in various places as the car warmed up with about 1700 rpm adjusted on the throttle screws.
I will give the figures as I read them but please bear in mind the gauge is affected by reflectivity of the aluminium or rubber or matt black paint. I reckon a possible 4deg F variation. Obviously I tried to pinpoint the same spot with the laser each time but the distance from the surface also affects the instruments field of view and hence temp reading.
The warm up run was measured in Fahrenheit and shows seven sets of readings from 9 areas, each set taking about a minute to do, so I was measuring continuously. Time ran from top to bottom and then left to right.
The diagnosis run that follows ,shown in Centigrade, has same 9 measuring points with the engine up to temperature. The electric fan kept switching on its thermostat which was set at 75C. The run was done at normal idle of 800 rpm.
Header tank....................67 84 117 138 160 185 187--86 72
Left rad outlet..................69 86 120 142 159 181 186--77 74
Right rad outlet................69 86 116 136 162 157 186--74 70
Left Water transfer...........82 93 128 151 176 190 196--69 72
Right Water transfer.........89 86 116 133 146 152 169--54 53Why
Top timing cover..............75 85 116 131 147 163 161--70 64
Water pump out...............76 91 117 131 148 161 160--67 66
Left head next to 2 spark..92 154 141 158 184 189 xx--72? 85
Right head next to 1 spark98 116 138 157 181 xx xx ---79? 69
Why? I do not know why this consistently read so low as the head seems to be cooling the water!!!
the ? indicate I suspect they should be transposed. Will recheck!
Note the considerable differences between left and right water transfers.
Next I measured the temperatures as close to the spark plugs as possible
and also the exhaust manifold temp at the outlet of each cylinder
No 1...87 130
No 2..90 170
No 3..85 153
No 4..79 153
Oil sump 65
Oil Filter 74
Oil cooler in 67
Oil cooler out 66
Last edited by Forumadmin on Thu Mar 05, 2009 10:58 pm, edited 5 times in total.
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Alastair Gregg
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Temperature readings
The exhaust manifold temp difference between Plugs 1 and 2 is around 25%. Initial thoughts were all around mixture but if that was the case I would expect the plugs to work at similar elevated temperatures But just over 3% difference blows that theory clean out of the water. I seem to recall your compressions being good and similar too, but if Plug 2 was giving a better compression than the others that might go some way to explaining the variations.
Anyone else any thoughts?
Anyone else any thoughts?
Compliments of the Season,
Alastair Gregg
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Leo and I discussed at length these initial results.
1. Exhaust temp differences can be explained because exhaust gas from No 4 heats No 2 and gas from No 1 heats No 3. I did quite a lot of investigation around the exhaust to see where the differences were. Really need a thermal image camera! On this basis though you would expect No 3 to be the hotest as it has gas of all four cylinders passing over it.
2. Spark plug temps also reveal no 2 hotter than 4, and no 1 hotter than 3. That can be explained by cool water from rad travelling over 4 and 3 first. But clearly No 2 is 10 degrees hotter, much more than the 2 degrees between 3 and 1. So either there is something wrong with 2 or we have some affect from the distributor shaft restriction in the waterway.
Clearly I need to look closely at No 2 with Colourtune and compression tester . I have done this before but just need to recheck.
Will give it thrash along a motorway and then look at temps this weekend.
I still suspect something wrong with the DelOrto carb as I am not happy with the inlet note, it barks on rapid acceleration. Could be a hot cam as although I checked lobe heights I did not check angles. If I have to, I will swap with known good carbs on Jup. The last time I checked with Colortune I had the head gasket issue and was concentrating on No 1 cylinder. But no 2 did look OK.
Those looking at Oil cooler temps may be surprised at low temp difference. This may be due to the oil thermostat not opening at 66deg and only allowing a trickle through. More investigation needed. I will see if I can check temps on all 4 inputs to the thermostat but it is hidden in the wheel arch.
Some may wonder at anomolies during the warm up run. This may be due to the fan cutting in. Note there is no mechanical fan on this beast.
1. Exhaust temp differences can be explained because exhaust gas from No 4 heats No 2 and gas from No 1 heats No 3. I did quite a lot of investigation around the exhaust to see where the differences were. Really need a thermal image camera! On this basis though you would expect No 3 to be the hotest as it has gas of all four cylinders passing over it.
2. Spark plug temps also reveal no 2 hotter than 4, and no 1 hotter than 3. That can be explained by cool water from rad travelling over 4 and 3 first. But clearly No 2 is 10 degrees hotter, much more than the 2 degrees between 3 and 1. So either there is something wrong with 2 or we have some affect from the distributor shaft restriction in the waterway.
Clearly I need to look closely at No 2 with Colourtune and compression tester . I have done this before but just need to recheck.
Will give it thrash along a motorway and then look at temps this weekend.
I still suspect something wrong with the DelOrto carb as I am not happy with the inlet note, it barks on rapid acceleration. Could be a hot cam as although I checked lobe heights I did not check angles. If I have to, I will swap with known good carbs on Jup. The last time I checked with Colortune I had the head gasket issue and was concentrating on No 1 cylinder. But no 2 did look OK.
Those looking at Oil cooler temps may be surprised at low temp difference. This may be due to the oil thermostat not opening at 66deg and only allowing a trickle through. More investigation needed. I will see if I can check temps on all 4 inputs to the thermostat but it is hidden in the wheel arch.
Some may wonder at anomolies during the warm up run. This may be due to the fan cutting in. Note there is no mechanical fan on this beast.
Last edited by Forumadmin on Thu Mar 05, 2009 9:39 am, edited 1 time in total.
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Keith Andrews
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Digital thermometers infra red /thermal have been used for yrs diagonins engine issues...well in small block chevs I know offIf it can pinpoint a human condition perhaps it could for a Jowett.
ie low temp on a header runner indicates not firing or bad spark on that cylinder....even so one still gets a great variation between center cylinders and cnr (V8) becuase of slightly different fuel mixtured due to longer valley cover runner to the cnrs.
One cannot expect a completly uniform temps, due to alsorts of stuff from air currents over the surface, how thick the metal is around water and oil galleries , the speed at which the water pump is going, the amount of water going thru...and if that water is closer to the radiator, or has passed thru several galleries to get to a particular point in the engine.
Just cause a partular part is a little hotter than anoter it doesnt mean poor design or something is wrong...except with in reason exuast primaries.
Its like checking a battery with a hydrometer, in theory all cels should be the same, in practice they are not, and for a dud battery one is not looking for low readings but for a cell that is quite different to the rest.
My Spelling is Not Incorrect...It's 'Creative'
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Variations in temperature
Agreed small amounts of variation in measurement are to be expected. Due to many different reasons Inaccuracy in measurement. Location of the laser and all the other points you make. However a 25% ish increase is worthy of note. I'm not saying it is the source of the problem but it has certainly pointed Keith in a direction to pursue, which is all I was saying when I suggested it.
Compliments of the Season,
Alastair Gregg
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Spent Saturday rechecking everything. First, compression on all cylinders was 150 psi +/- 1 psi. Then the ignition timing to TDC needed retarding about 4deg as I had probably set on hill pinking test. Advance on speed and vacuum advance also checked. Then No2 and No1 mixture with Colour Tune. Slight weakening required on No2. Then idle throttle balance. Also checked mixture on acceleration and steady fast speed.
Just in passing, the DellOrto number on the tag of the FRD carbs is R5743.
gallery2.php?g2_itemId=9571&g2_imageVie ... =x9dde9a44
Then did temp check
Head Rad..36 43 61 71
L Bot Rad..37 50 63 71
R Bot Rad..35 50 61 71
SparkPg 4..39 45 60 73
SparkPg 3..37 62 69 72
SparkPg 2..44 60 72 80
SparkPg 1..42 64 70 71
LWatTrans..31 44 50 66
RWatTrans..32 47 51 63
LTimgCovr..26 37 41 52
RTimgCovr..27 41 43 52
WtrPumpIn..41 56 62 65
WtrPumpOut.31 39 47 55
Note that the Water pump out (55) was measured on aluminium and read 70 on pipe. So the black surface makes a difference. Perhaps I should paint the engine black!
After talking with my friend Bill over a couple of bottles of wine the previous night I thought I would re-check the oil cooler.
Oil Filter 63
Oil pipe in 66
Oil pipe return 55
Cooler in 64
Cooler out 62.
Some anomolies here and suspect it is the reflectivity again.
So with a smooth idling engine decided to take the parents for a long drive through the woods and hills to see the snowdrops. Started with a thrash along the bypass which starts with a long hill, so good to get it warmed up. Seemed to pull fairly well, perhaps not as powerfully as the rally Javelin. However, did start to overheat with 100C on the ether gauge, so stopped and checked header tank temp with infra red. Was reading 90 to 94; but the bottom of rad was 80 and heads were 110L / 95R. That was with both rad fans and the heater on. The thing I could not explain was that the thermo gun read 110 at the top head face by No 2 cylinder and only 80 an inch away on the water transfer. Ok the outlet to the WT could be blocked. But it was the same on the other side.
Also checked the oil cooler which read 88.
Continued driving around country lanes with both fans on, the temperature gradually came down to 85. It was OK in traffic jam for 15 minutes as well.
Back on the by pass at 65 to 70 mph the temperature rose again. Stopped in the pub for a pint of Speckled Hen.
Today checked water which had dropped about and inch to just cover the thermo bulb so it had lost about a pint of water. Will check for leaks again. More discussion with Bill ensued and I decided to change water pump for a fully reconned one. Problem is that I need to fit an ally flange to it. This flange does away with the rubber pipe so is not pulled over by fan belt. Went around Bill's this evening to turn up the aly casting on his lathe. Now ready to fit this week.
Just in passing, the DellOrto number on the tag of the FRD carbs is R5743.
gallery2.php?g2_itemId=9571&g2_imageVie ... =x9dde9a44
Then did temp check
Head Rad..36 43 61 71
L Bot Rad..37 50 63 71
R Bot Rad..35 50 61 71
SparkPg 4..39 45 60 73
SparkPg 3..37 62 69 72
SparkPg 2..44 60 72 80
SparkPg 1..42 64 70 71
LWatTrans..31 44 50 66
RWatTrans..32 47 51 63
LTimgCovr..26 37 41 52
RTimgCovr..27 41 43 52
WtrPumpIn..41 56 62 65
WtrPumpOut.31 39 47 55
Note that the Water pump out (55) was measured on aluminium and read 70 on pipe. So the black surface makes a difference. Perhaps I should paint the engine black!
After talking with my friend Bill over a couple of bottles of wine the previous night I thought I would re-check the oil cooler.
Oil Filter 63
Oil pipe in 66
Oil pipe return 55
Cooler in 64
Cooler out 62.
Some anomolies here and suspect it is the reflectivity again.
So with a smooth idling engine decided to take the parents for a long drive through the woods and hills to see the snowdrops. Started with a thrash along the bypass which starts with a long hill, so good to get it warmed up. Seemed to pull fairly well, perhaps not as powerfully as the rally Javelin. However, did start to overheat with 100C on the ether gauge, so stopped and checked header tank temp with infra red. Was reading 90 to 94; but the bottom of rad was 80 and heads were 110L / 95R. That was with both rad fans and the heater on. The thing I could not explain was that the thermo gun read 110 at the top head face by No 2 cylinder and only 80 an inch away on the water transfer. Ok the outlet to the WT could be blocked. But it was the same on the other side.
Also checked the oil cooler which read 88.
Continued driving around country lanes with both fans on, the temperature gradually came down to 85. It was OK in traffic jam for 15 minutes as well.
Back on the by pass at 65 to 70 mph the temperature rose again. Stopped in the pub for a pint of Speckled Hen.
Today checked water which had dropped about and inch to just cover the thermo bulb so it had lost about a pint of water. Will check for leaks again. More discussion with Bill ensued and I decided to change water pump for a fully reconned one. Problem is that I need to fit an ally flange to it. This flange does away with the rubber pipe so is not pulled over by fan belt. Went around Bill's this evening to turn up the aly casting on his lathe. Now ready to fit this week.
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Following the fitting of the new pump (with the mechanical fan replacing the electric one in front of rad) did a test run which really did not seem to have improved overheating. Then left it for a few days as I had to go to Devon to sort my parent's house ready for a new tenancy.....
This week's rejuvenated efforts to fix the heating problem are as follows.
1. Took the pump off again to try to find leak in pump. Connected pump shaft to drill and ran for 5 minutes in hope of facing off the water seal.
2. Refitted, this time with O ring seal between two modified flange faces where the rubber pipe connector used to be.
3. Checked main jets were same as on Jup. They were; but noticed that the carb bowls were dry on the Javelin, but full on the Jup.
4. Checked operation of mechanical petrol pump. Seemed OK but fitted an electric one anyway to test.
5. Gave test run and engine note sounded better and overheating seemed better (but it still climbed up to 85) although it was a cold day.
6. Noticed water inside engine compartment again.
7. Checked volume of petrol delivery which seemed OK so pipe not blocked.
8. Gave an extended test and over heating was still there but certainly not as bad as it was.
9. Electric pump positioned above water transfer started to give problems.
10. On return from long run noticed high pressure spurt of water coming from hole in water pump casing. No it is not the one that should be there behind the seal, but one on circumference of impeller created from a thin body casing. On immediately draining the system with rad cap still on traced the hissing suction noise with a bit of pipe stuffed in my ear (which proved it was just the one hole in the system!) I have plugged it with araldite having had to take the pump off again to find and clean. Initially I thought the whole body was cracked and rubbed with chalk which showed where the hole was as the seaping residual wetness darkened the chalk.
11. All back together and reconnected mechanical petrol pump.
12. Removed canvas protection strip between body and bonnet. Raised bonnet with 1/4inch aly plate.
If that does not fix it I will probably have to resort to going back to Zeniths! Or just give up and drive slowly.
This week's rejuvenated efforts to fix the heating problem are as follows.
1. Took the pump off again to try to find leak in pump. Connected pump shaft to drill and ran for 5 minutes in hope of facing off the water seal.
2. Refitted, this time with O ring seal between two modified flange faces where the rubber pipe connector used to be.
3. Checked main jets were same as on Jup. They were; but noticed that the carb bowls were dry on the Javelin, but full on the Jup.
4. Checked operation of mechanical petrol pump. Seemed OK but fitted an electric one anyway to test.
5. Gave test run and engine note sounded better and overheating seemed better (but it still climbed up to 85) although it was a cold day.
6. Noticed water inside engine compartment again.
7. Checked volume of petrol delivery which seemed OK so pipe not blocked.
8. Gave an extended test and over heating was still there but certainly not as bad as it was.
9. Electric pump positioned above water transfer started to give problems.
10. On return from long run noticed high pressure spurt of water coming from hole in water pump casing. No it is not the one that should be there behind the seal, but one on circumference of impeller created from a thin body casing. On immediately draining the system with rad cap still on traced the hissing suction noise with a bit of pipe stuffed in my ear (which proved it was just the one hole in the system!) I have plugged it with araldite having had to take the pump off again to find and clean. Initially I thought the whole body was cracked and rubbed with chalk which showed where the hole was as the seaping residual wetness darkened the chalk.
11. All back together and reconnected mechanical petrol pump.
12. Removed canvas protection strip between body and bonnet. Raised bonnet with 1/4inch aly plate.
If that does not fix it I will probably have to resort to going back to Zeniths! Or just give up and drive slowly.
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Keith Andrews
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Refresh so when you a hammering along the temp goes up
When crusing back lanes it drops
100 to 80 bottom of radiator..
OK on idle.
Partly blocked cores...this can usually be identified with a cold morning start up and feel where the radiator warms and stays cold
Is the dizzy cent advance swinging out in spec total / rpms
Sure the idle can be correct..the best method to set advance is know the rpms and total, take the rpms up then set the advance.
What is at idle is just there to for even idle and fire up...it is not critical...what is critical is the curve once the car is moving.
If think it is carb (lean) , throw some rich jets in
When crusing back lanes it drops
100 to 80 bottom of radiator..
OK on idle.
Partly blocked cores...this can usually be identified with a cold morning start up and feel where the radiator warms and stays cold
Is the dizzy cent advance swinging out in spec total / rpms
Sure the idle can be correct..the best method to set advance is know the rpms and total, take the rpms up then set the advance.
What is at idle is just there to for even idle and fire up...it is not critical...what is critical is the curve once the car is moving.
If think it is carb (lean) , throw some rich jets in
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If you have a look at the table of temps in a previous post you will see the temp gradient in the rad which lead me to suspect the water pump. It was hotter at bottom of rad than the top.
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The outside temp went up to 18 today so gave the Javelin another thrash. Have cured the hole in the pump so no loss of water now.
There were two miles of stop/start to the dual carriageway when the temp stayed below 80c, then kept between 60 and 70mph for 3 miles. Temp started to rise, reaching 90c, so off at next junction, when temp rose to just below 100 on gauge which is actually about 93c. So then cruised back at 50mph, temp was stable just below 100 even in traffic. Of course, electric fan was on full bore as well as mechanical one.
Plenty of hot air coming from the gap by windscreen.
Immediately checked temps on rad with engine switched off.
Header tank 90, top left rad 85, bottom left 81 , top right 63, bottom right 88 with linear change between those temps in all four directions. I double checked those readings. I can only explain that with some weird convection taking place, perhaps via cabin heater. How that top right remained so cold could really only be explained by a blocked rad and local cooling, neither of which is likely.
When the engine was restarted, the temp gradients were as expected about 78 at top of rad and 65 at bottom. Left head was 88 and right head 77.
Checked no water loss and no bubbles.
So now I really am considering plan Z.
I will recheck advance curve; but as part of this detective story it has had a reconned dissie and a recored rad. Neither of which have been the cure.
It still could be a problem with the left head, camshaft profile (but not opening point), significant need for richer jet setting with these heads, or possibly two bad distributors (I did have overheating on the Jup which was caused by worn advance stops giving too much advance.) But I am pretty sure the original dissie did work ok in the Jup and the current one is brand new. (Could still be faulty though.) Note I have checked advance with strobe before. I may well try the thrash and then coast to a lay-by trick to see the state of the spark plugs and hence full bore mixture. Could also use my CO meter but neighbours might not like the car going full bore in the garage !
There was some hesitation that I tried to investigate which could be lack of fuel at full bore, spark plug breaking down, or vacuum advance. But it was not consistently repeatable and very occasional. Oh for a rolling road and diagnostic set up but I am not going to pay £100 an hour to find out on the one that is only half a mile away.
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The outside temp went up to 18 today so gave the Javelin another thrash. Have cured the hole in the pump so no loss of water now.
There were two miles of stop/start to the dual carriageway when the temp stayed below 80c, then kept between 60 and 70mph for 3 miles. Temp started to rise, reaching 90c, so off at next junction, when temp rose to just below 100 on gauge which is actually about 93c. So then cruised back at 50mph, temp was stable just below 100 even in traffic. Of course, electric fan was on full bore as well as mechanical one.
Plenty of hot air coming from the gap by windscreen.
Immediately checked temps on rad with engine switched off.
Header tank 90, top left rad 85, bottom left 81 , top right 63, bottom right 88 with linear change between those temps in all four directions. I double checked those readings. I can only explain that with some weird convection taking place, perhaps via cabin heater. How that top right remained so cold could really only be explained by a blocked rad and local cooling, neither of which is likely.
When the engine was restarted, the temp gradients were as expected about 78 at top of rad and 65 at bottom. Left head was 88 and right head 77.
Checked no water loss and no bubbles.
So now I really am considering plan Z.
I will recheck advance curve; but as part of this detective story it has had a reconned dissie and a recored rad. Neither of which have been the cure.
It still could be a problem with the left head, camshaft profile (but not opening point), significant need for richer jet setting with these heads, or possibly two bad distributors (I did have overheating on the Jup which was caused by worn advance stops giving too much advance.) But I am pretty sure the original dissie did work ok in the Jup and the current one is brand new. (Could still be faulty though.) Note I have checked advance with strobe before. I may well try the thrash and then coast to a lay-by trick to see the state of the spark plugs and hence full bore mixture. Could also use my CO meter but neighbours might not like the car going full bore in the garage !
There was some hesitation that I tried to investigate which could be lack of fuel at full bore, spark plug breaking down, or vacuum advance. But it was not consistently repeatable and very occasional. Oh for a rolling road and diagnostic set up but I am not going to pay £100 an hour to find out on the one that is only half a mile away.
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Keith Andrews
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If testing CO mixtures etc at upper rpms, the engine also needs to be loaded...hence why chassis dynos have rollers.Could also use my CO meter but neighbours might not like the car going full bore in the garage !
I went thu this when dialing in the camaro for dedicared LPG couple decades ago...so ran the CO inside the car on road testing ..very diff from stationary reving . The engine vaccuum behaves very diff in loaded and unloaded states.
Worn pins on dizzy will not over advance enough to cause temp rise...removing VA if that is the case compensates if under cruise
under advance on the power curve is far more sensitive to performance, economy any heat..
ie taking say 36 deg @ 3200 rpms, if one increase advance very little is noticed untill one get way up around mid 40s..althu it is bad long term for the engine and big increase in NOx
If one decreases there will be a piont that drop of in power economy is noticable..depending on engine dynamic compression ratio this will be around the 27 to 30 degrees...and temps will rise
Another issue that could be the case is incorrect spring tensions on the weights...doubt if too light would be the case, this would be noticed with engine increasing /decreasing speeds at idle with springs to light to hole the eights in
Too heavy and the total rpms will be way above spec...
If running for performance general rule of thumb is to have springs come off about 150 to 300 above idle speed..using diff weight springs and/or slotted springs you can change the shape of the curve.
Increase fuel octane increase mixtue increase advance
Increase DYNAMIC compression ratio decrease jets decrease advance.
Most think about just Compression ration this means squat...it is the dynamic ration at a given rpm on a given CR and this changes with cam profile overlap, duration and to a lesser extent rate of lift. NOT lift.
Going on you symtoms, I would
1/ manually clean rradiator cores..which should be done as routine when building and engine.
2/check pump impleller is 100% secure, not slipping
3/check advance curve...thu if radiator is good this has very little effect in practice on old engine
4/ check mixtures and air leaks.
5/ Run a HC check on the radiator.
Engines on the highway, usually 30mph + espec old cars with over built radiators, do not need a fan..there is enough air from the speed of the car to cool...the fans kick in or need to increase air flow at stationary and slow traffic speeds
Edit:
PS when u use the temp sensor is the distance from the target the same for every reading....this is estentual as the temps will vary as the the inverse squ of the distance....and to read correct temp it must be at the distance in the instuction book or on the back of the unit.
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