Jupiter engine cooling

[chapman]

I am seriously trying to put mileage onto my Abbott bodied Jupiter so that I can get it to be as reliable as my standard bodied Jupiter which has now done 17000 miles with no repairs (most of this on Jupitours and rallies such as Denmark and Tulip).
My main problems seem to be related to cooling the engine and looking at the engine bay I can see where some of the problems lie
Firstly the air intake (by the numberplate) is missing because of the bonnet design,so I am short of air in.
I could fit some cut out grilles at the sides of the main bonnett grill like the standard car but I don't want to do this because the picture in Eds book shows that there were no holes other than the grille and the two nostrils above it so I want to keep its identity like the book.
I have fitted a six inch oil cooler in the inner wing on the wheel side and a fan on the inner wing to cool it but this was not quite enough and it still boiled on hills so I modified a 13 blade mini cooling fan to fit on the Jupiter pump but this made very little difference so I have now fitted a 9 inch curved blade pusher fan to the front of the radiator having first sawn off the end of the water pumped shaft.
I got this fan from www. Carbuilder solutions .co.uk for £42 and the thermostatic controller for £24.
The fan fits to the radiator by long thin plastic ties which pass through the matrix and the thermostat bulb fits in the top hose.
I set it at 75c and this seems to work OK but I have not yet tried it on a fast road run which is my next job.
If this does not work then I will have to look at air scoops underneath the front and possibly louvres at the rear end of the bonnet.
I am now realising that special bodied cars can have these problems because they are not the same as standard bodied ones in design and the original airflow was obviosly part of that design which has not been considered by the special builders.

[Forumadmin]

I am having the same problems with my Javelin and Jupiter fitted with Dellorto carbs. Below 60 mph no problems, above that both cars get hot. The engine in the SC fitted with Zeniths does not. Is it the engine block, heads, carburation or timing that causes the overheating? It is not the air flow, but could it be the petrol?

The SA definately did not overheat on the desert rallies with Delorto's when fitted with the engine now in the SC. I think the Javelin did overheat many years ago when fitted with the Zeniths. I am close to swapping back to Zeniths just to prove it is not the carbs.

I suspect it is all to do with petrol. The Dellortos are leaner at the top rev range but need to take it on a rolling road to check. The modern petrol also burns slower and hotter leaving more residual heat. I have tried BP ultimate which was better; but not that much. ther is pinking on the JUp at half throttle which retarding does not seem to get rid of. High compression, hot spot?

I short Tom , welcome to the club, although it may be air flow in your case. I even have the heater on full blast which must remove 20% of extra heat. An alu rad is 20% better as well.

[chapman]

No ,I think it is definitely airflow because the standard Jupiter has the same radiator the same zenith carbs no oil cooler and it never gets above 75c. and I always get my petrol from the same garage,
The javelin also has same carbs and same petrol and that never gets hotter than75c.
Allthe cars have timing checked with the same timing light and tappets set in the same way and only the Abbott boils but I will sort it eventually.(I hope)

[Chris Spencer]

This problem is not just reserved for Jowetts - I have the same problem with my V8 Rover - the car is fine while it is moving - but under 20 mph or standing in traffic is just asking for the car to boil or the petrol to evaporate through heat build up - once you get in to speeds over 65 mph you have all on to keep the water temp from boiling - this is a known fault throughout the owners club - Keith hit the nail on the head with the modern day petrol creating higher temps. Like most others I have tried the obvious routes, flushed out the block, reset timing, new 3 core rad, modified water pump all to no avail.

Until now - The Rover has been off the road for the last 18 months undergoing a major mechanical referb along with some cosmetics to the engine bay. The car has only covered 20,000 miles from new but spent 20 years in a muesum - however caliper seals / suspension bushes etc do not last forever. I have read several reports about the course of action I have taken with the exhaust manifolds and all praise the effect.

So off they came and taken to a company near Didcott call 'Zircotec' who sandblasted then sprayed the manifolds with a ceramic coating (various colour choices) - bolted back on and now well worth the effort - the under bonnet temp on the car has been reduced by 35% !!!! - This process is used by all the F1 & world rally teams to reduce the temps under the bonnet - it is not that cheap and cost me a little under £400 to have the two 4 branch manifolds done - however, £400 verses a very expensive engine rebuild is no contest.

www.zircotec.com / 01235 546050

[Jack]

This problem is not just reserved for Jowetts - I have the same problem with my V8 Rover - the car is fine while it is moving - but under 20 mph or standing in traffic is just asking for the car to boil or the petrol to evaporate through heat build up - once you get in to speeds over 65 mph you have all on to keep the water temp from boiling - this is a known fault throughout the owners club - Keith hit the nail on the head with the modern day petrol creating higher temps. Like most others I have tried the obvious routes, flushed out the block, reset timing, new 3 core rad, modified water pump all to no avail.

Until now - The Rover has been off the road for the last 18 months undergoing a major mechanical referb along with some cosmetics to the engine bay. The car has only covered 20,000 miles from new but spent 20 years in a muesum - however caliper seals / suspension bushes etc do not last forever. I have read several reports about the course of action I have taken with the exhaust manifolds and all praise the effect.

So off they came and taken to a company near Didcott call 'Zircotec' who sandblasted then sprayed the manifolds with a ceramic coating (various colour choices) - bolted back on and now well worth the effort - the under bonnet temp on the car has been reduced by 35% !!!! - This process is used by all the F1 & world rally teams to reduce the temps under the bonnet - it is not that cheap and cost me a little under £400 to have the two 4 branch manifolds done - however, £400 verses a very expensive engine rebuild is no contest.

http://www.zircotec.com / 01235 546050

Chris, could you get a similar performance from using exhaust wrap tape? A cheaper alternative, though definitely a lot less attractive and will add a small amount of weight once complete manifolds are covered. Do Zircotec have a guide on the relative benefit of one over the other? Any reviews/reports from other owners who have tried both?

On a Jupiter I'd have thought that coating the front two sections of the exhaust would be sufficient, the rear pipe goes straight under the bulkhead pretty much so shouldn't be contributing much to overall temperature - the front pipe seems to be calling out for a thermal covering if nothing else to avoid burns when going under the bonnet for essential repairs on the roadside.

Jack.

[Chris Spencer]

Jack - You probably could although the distance between the branches would prove quite a challenge to wrap on the Rover as they are quite small and as you point out it would look rather ugly and I for one am not into ill wrapped and ugly manifolds hence I spent the money and got it done properly. A Jup would be easy to do with the wrap tape and you could keep it quite neat. Zircotec also carry a range of heat shield mats / pads which are very low profile i.e. 1>2 mm thick.

[Srenner]

Headwrap works very well, but it promotes rapid deterioration of the pipes. We have used it on race motors for years, but it always results in cracked and fragile tubing. Add in wet weather soaking it when cold and then burning off and your exhaust pipe has a very short life. Coating is the more expensive but cost effective solution.
Scott

[Robin Fairservice]

If the problem is under bonnet temperatures, then may be the issue is how does the hot air get out of that space. Perhaps on the Abbot Jupiter some air outlets are more necessary than inlets. I remember that the original Mini's radiators vented into the front wheel space because that was a low pressure area. The Javelin vents on each side behind the radiator into the wheel space. A hole cut out in that area would not be visible. Our Australaian friend operate Javelins and Jupiters in hot temperatures. I drove a 1949 Javelin 1700 km from Adelaide Hills to the JOAC 50th Rally at Armidale and it was pretty hot. The only time the engine temerature went up was on a couple of long hills, and changing down into third helped control the temperature.

[chapman]

Yes Robin you may be right but again the Abbott is a different shape behind the radiator to the standard model. and it does not have the two big holes that the standard model has there .
Looking at the space design without any actual science I would say that the airflow form the radiator is intended to go upwards to vent from the top of the bonnet but I dont want to cut holes and put in some louvres except as a last resort so I will try the pipe wrap technique first.
I did about 20 miles fairly quickly last night and it did not get anywhere near boiling but the night was fairly cool and I had enriched the mixture slightly so we are getting there slowly ,
I also have to consider that it is a newly built engine which can be a bit tight although I use STP in it so it may be better when its run in a bit , but any ideas are still welcome

[Forumadmin]

Get it in a wind tunnel or stick lots of little tails over the front, sides and windscreen to see where the air flow is. Drive at 60 with someone taking photos with a high speed camera/video from another car or just observe.

Javs had some unusual low pressure points. I was told that sealing the rear of the bonnet was important; although now I have it raised by 1 cm!

If you can afford one get a laminar flow rad as fitted to some exotic cars.

[chapman]

Thanks ,Now that sounds a bit more scientific and raising the back edge of the bonnet half an inch sounds do-able so I will give that a try first,
May also try some home made baffle /deflector plates inside the bonnet behind the radiator

[Robin Fairservice]

One of the older Corvettes would overheat if the shrouding on each side of the radiator was missing. It was much easier for the air to go past the radiator instead of through it. I have no idea what your car looks like under the bonnet, but is there any shrouding on each side of the radiator to ensure that air passes through the radiator? The Javelin has shrouds on each side of the radiator.

The scientific approach with air tufts would be the best idea to see where the high and low pressure areas are. I believe that the lower front of the windscreen is a high pressure area, and one finds that most modern cars draw in air for the heating system there.

[Keith Andrews]

Rounning hot over 30 mph...
Ambiant air temps causing any more than a couple degrees is load of rubbish.
There is more air going thru the radiator than any fan would hope tp do.
1/ head gasket ...check radiator for HC.
2/ Check timing ..there is a piont of 2 to 3 deg variance that an engine runs hot, and if the mixture is a litle lean at the same time...makes very suspetable to run hot.
3/ Blocked or restricted cores...flushing doesnt fix these..removing header tanks and manually cleaning is required.
quicj check for this ..1st start of the day, as the thermostst opens, feel the radiator cores for cold xpots
4/Bottom radiator hose re enforcing spring corroded away (also see 3/)..and when this happens they are generally a bit soft....cruising down the highway, it sucks closed or near closed...and even more so if some cores are blocked.
5/Therostat crook....remove and check in a jug of water heating up with a thermometer... does it open at the correct temp and open all the way? always check a new one before installing
6/ Spun pump impeller...it turns but as soon as a few rpms are up it partly spins on the shaft.
7/ Chrome polished sumps tappet covers without cooling fins..over 1/2 the engine heat is transfered thru the tappet covers and sump..Chrome/polished reduces the transfer of this heat dramatically over a thing matt black flat.
"Chrome for show, Black for track"
8/Vapour lock...doent happen anywhere as much commonly believed...check the thermost have a bleed hole, if not drill on....and to be sure, park the car facing up a hill (or jack the front way up) and fill the radiator.
9/ Coats and coats of paint on the radiator that ineffect coats it with a thick layer of insulating 'plastic'....just a very thin layer of matt black...

And as mentioned above about corvettes...well ANY SB or BB chev...no or incorrect fan shroud will run the car hot at low speeds or idle. Having a shround increases fan efficiency a huge amount...stops spill off the ends of the blades.
Non shrounded fans only work where radiators are way over sized for the application...assuming no blocked cores..which is very common on old cars.

Before anyone suggests,
a colder thermostat DOESNT change runing hot...all the thermostat does is bring the engine upto running temp fast reducing wear etc.
Colder plugs do not influence the running temp of the engine, it is the abilty of transferering electrode heat away.

These old car cooling systems ..up to the early/mid '70s where way over built...stock...so many old wives tails about cooling systems still abound, orgininating because ppl patch /hide the real issue with a 'fix' that works simple because it compensated for the real issue....then say "these cars where built with a fan too small " or some similar BS.
In fact many of these old systems are so damn efficient in flow thru of the radiator and GPH of the pump (when in good condition) not having a thermostat in to restrict flow will cause the engine to run very hot.

Another issue about the cooling system , it is not treated seriously when ppl build engines...yep things like a new oil pump regardless is std practice, but they forget to treat the cooling system in the same manner....new engine, pump beatings and impellers checked, radiator header pulled and manually cleaned, new hoses...espec the bottom hose.

Thats cooling systems in a nut shell.

[Peter Holden]

I had the same problem with my Jupiter in the early days. 20miles down the road at about 60 mph and it would be boiling and I would have to stop. Street cred went out the window after just passing Trabant!! I have the original fan and added an electric fan on the other side of the radiator, this helped. But the real inprovement came when I added some closing pieces between the radiator and the inner mudguards. The air was taking a short cut and not going through the radiator. I have the small or short radiator - a taller one will not fit.

Another cause for over heating is brake binding. Go for a run and check the brake drums after about 10 miles. If one is hot and the others are cold that is likely to be your problem, well it is not helping.

[Forumadmin]

Air pressure on the Javelin or Jupiter rad due to forward motion is not that great as it is behind all manner of obstructions. On the Javelin there is also not much in the way of exit for the hot air either.

Keith A's list has no doubt been run through by most people trying to solve an over heating problem. Some may never really find out what cured a problem and some may not ever fix it; but just drive around it. On my Jup the header tank gets hot but the heads remain good , mainly due to the super efficient aly rad. jen's Jav may be the same; but I do not yet have head temp sensors fitted. As I hope you have all read in .. http://jowett.net/forum/viewtopic.php?f ... nced#p8492
detailed temp readings were taken at many points on the engine and cooling system.