Which head gasket ?

Post by **Forumadmin** » Sun Oct 12, 2008 10:26 am

I am trying to figure out a way of identifying which head gasket has gone.
So far I have tried:

Doing a compression meter test on each cylinder. All were at 170 psi except for no 3 (180psi) .

Running the engine with out a spark plug in each of the four cylinders in turn and then looking to see if the bubbles that came to the water surface in the radiator stopped.

Putting a cotton bud into each cylinder to see if there was any standing water.

Last resort is to spin a coin; although No 3 may be favourite with the logic that water being sucked in would raise compression and that it is only under the extreme combustion pressure that the gasket leaks out . Pretty weak argument though! Alternatively go for No 1 with the argument that it should be the same as No3 . Anyway it is the same head!

TedAllen · Post by **TedAllen** » Mon Oct 13, 2008 5:29 pm

Could you describe the symptoms and why you think a gasket has gone.
Do you have excessive steam from the exhaust ? If so, try running it with each plug lead off and see if the steam reduces at any time. Check the oil for 'mayonnaise' this will show on the dipstick as a creamy oil/water mix. Leave the car for a few days with the plugs out and the rad full of water...see if a cylinder fills uo. Does the engine feel as if it has seized up when you try and start ? If so, it may have hydraulically locked due to water in one of the pots...take the plugs out and swing it over with the handle, you'll soon see and probably feel which pot is the full one.
The more information ....the more we can help.
Ted

Post by **Forumadmin** » Mon Oct 13, 2008 7:30 pm

No steam, no mayo, no water (viz cotton buds), hence no seize, little loss of water.

Info = 'bubbles in rad' and overheats within 10 minutes of running.. Have checked for CO in water at garage and using my own CO sniffer. These were both negative which meant I went a few more weeks trying to prove overheating was head gasket. Note rad is brand new, has oil cooler, has new wider aly transfers between head and block, has cast aly sump, all in attempt to reduce over heating.

Also has two powerful electric fans. mechanical fan is not fitted.
Only water pump left to change; but this was delayed in being reconditioned. Thermostat has been taken out, even though it was checked. Valve and ignition timing checked, ( Distributor changed to new one from electronic ignition. ) mixture checked with Colour tune

Car is running well very smooth tick-over. I have had many gaskets go but not for 20 years since I figured out the best way to fit. I suspect that this may be a cracked head if not the gasket; it was one from Mr Tucker!

Keith Andrews · Post by **Keith Andrews** » Mon Oct 13, 2008 8:43 pm

Have a look in each cylinder with a trch, a water leak will show a very clean piston
The most reliable test is the CO...if this is negitive u dont have exhaust leak into water

If the pump etc is moving water, the thermostat is checked with an electic jug and thermometer opening at correct temps and fully open and is the correct flow
The bottom water hose still has the renforced metal spring inside...if not the hose collaspes under suck, restricts flow

That leaves the most common issue running hot
Radiator...
Radiators are often over looked on engine rebuilds...regardles if it is only 12 months old...it should have the header tanks pulled and core manually cleaned and checked

The main cause of raditor 'failure' is the renforcing spring breaks away, and partly blocks and/or blocks several cores...on a rebuild, there is a certain amount of gasket seal 'dags that come off internally, these can the block the cores.

A general check for blocked cores, not completly reiable but a good indicator, and best done with thermostat in.
With rngine cold over night....fire up, and hold rpms up a little for good flow, and feel the cores, they should heat even, a blocked or partly blocked core will warm up slower.

Also not on some old engines..dont know if jowett is one....with no flow restriction in..thermostat, the engine can run hot....SB chevy with std factory raditor does it....
the reason is the pump has a huge gal/hr at off idle and above, the raditors are way over built..the water goes thru so damn fast it still come out the other end to hot.

Oh another issue could be the water pump impeller splines are not good and slipping on the shaft.

TedAllen · Post by **TedAllen** » Mon Oct 13, 2008 9:39 pm

Just as a note on Keith's first paragraph, If you can't see the piston tops easily, one of the plugs will also be cleaner than the other three at the working end if water is present in that cylinder.
Ted

Post by **Forumadmin** » Tue Oct 14, 2008 9:35 am

How do you explain bubbles in the radiator water? Especially when the water is warm not boiling. Could be cavitation but it occurs at only 3000 rpm or less. Could be air being sucked in to pump; but there are no leaks.

I have checked CO two different ways; but Dennis Sparrow thinks it can be an unreliable test.

It is not the rad
It is not the thermostat

Discounting bubbles, it could be blockage in head or the water pump (but I have taken that off and checked to make sure nothing had broken.

I will do a more prolonged test to see if it is using water; but if it is it is not a lot.

I have seen many cracked heads which this may be; although they have had new seats fitted.

Keith Andrews · Post by **Keith Andrews** » Tue Oct 14, 2008 8:30 pm

I have checked CO two different ways; but Dennis Sparrow thinks it can be an unreliable test.

Put it this way....The indicator fliud WILL chane if there is CO present..
the laws of chemistry will not fail....it is like saying litmnus test for acid/alkaline is un reliable..or water will not evaporate if boiled

IF the indiactor fliud has not been back flushed after each test, and/or the fliud has been contaminated, yes the test maybe unreliable..but that is because of human factor, not because of the test equipment.

A radiator freshly filled will show bubbles for some time...as the water releases trapped O2 and atmoshereic gases
And as small water bubbles attached to the interals slowly get torn off the walls
Even then some engines will throw a bubble..could be sucking a little air from water pump seals yet the seal will not leak water
I went tru this routine yrs ago...blocked cavities?? heads???
Some engines for no apparent reason thru a bubble every now and then...the camaro always has for 200,000 miles 30yrs and 2 rebuilds.
Why..havnt a clue..my truimph did, and so did the hunter way back.

If the CO test equipment/fluid is in good condition and -VE the bubbles are not emmission gases.

Post by **Forumadmin** » Wed Oct 15, 2008 9:23 am

Must try to get some of that fluid. Both garage and I used a gas analyser.

Keith Andrews · Post by **Keith Andrews** » Wed Oct 15, 2008 8:25 pm

Both garage and I used a gas analyser.

u mean an exhaust CO ?
Those things need a heap more than a couple bubbles to bring % levels high enough and long enough to get a reading

This is the thing u want...note the different fluids for petrol ans deseil engines

http://www.toolsource.com/combustion-le ... id=bizrate

Post by **Forumadmin** » Thu Oct 16, 2008 7:03 pm

Prices seem to fluctuate wildly from $8 in US to Â£25 for the same thing in UK
Anyway reason I put my trust in the gas analyser is it did prove it on the Subaru.

Keith Andrews · Post by **Keith Andrews** » Thu Oct 16, 2008 7:45 pm

Damn near any commercial work shop SHOULD have one of these..
Its one of those standard workshop tools...like a radiator pressure tester
or steering wheel puller or a rattle gun.
takes 2 mins to run a check...most garages will do it no charge...or drop off a 6 pack.

Tony Fearn · Post by **Tony Fearn** » Thu Oct 16, 2008 11:05 pm

most garages will do it no charge...or drop off a 6 pack.

It's so good to see that this system still exists in the world, but I don't think there are many U.K. garages who subscribe to it these days.

A packet of ten 'Woodbines' (a type of cigarette available in the 60's and 70's) was the usual tender when I was a young man and needed help from the motor mechanics etc with 'Mary Ellen'.

Thank goodness for the help available through the Club and JowettTalk!.

Tony.

Chris Cole · Post by **Chris Cole** » Fri Oct 17, 2008 12:13 pm

I used the method of removing all the plug leads from a cold engine. Then turned it over on the strtater moter for 5 seconds. Then inspect each plug in turn; a wet one is usually obvious since the plugs ought to be dry from the last engine run.

Post by **Forumadmin** » Sun Oct 19, 2008 8:35 pm

Did not get the CO2 indicator fluid; but because I have to have the car ready for a wedding next month did a final test.
Checked all cylinders did not contain water by poking a rag down each and slowly rotated crank till TDC on each. There was no water in any of them.

Filled rad right up and ran engine. No steam. Running beautifully. Some bubbles in rad on tick over. When I revved after leaving idling for a minute a number of large bubbles that had collected in the system were driven out.

Decided to take 1-3 head off. Easier said than done as first I had to remove the carb studs that are fixed to the Delorto adaptor. Then because this head (unlike the other one) has a protruding lip just above the water transfer hole, one side of the engine was jacked up to enable the head to clear the bodywork.

Close examination of the sealing surfaces showed some lack of shine on the copper of the gasket and steel of the head which indicates lack of pinch. Sure enough the liners had sunk to just 4 thou protrusion. Also thanks to this thread I was convinced that No 1 cylinder was the culprit as close to the suspect gasket area the piston had a clean patch presumably where it was washed with the steam, even though there was not an excess of steam from the exhaust.

So this job is going to take some time. I have in the past fitted extra shims under the liners without taking them out. I cut the correct sized shims diagonally put some gasket sealer on them and fed them around a slightly lifted liner. It did work and never leaked. But I think I was lucky.

Thanks again guys for your advice.

As I said these heads were obtained from Keith Tucker and I think too much was ground away from the sides of the combustion chamber which reduced the sealing width of the copper ring by 1,5 mm which on 5mm is a lot. So the gasket did not have much chance to start with. I will put them back and hope . Obviously nothing should be ground away just there!

Post by **Forumadmin** » Mon Nov 03, 2008 8:11 pm

I have loaded some photos of the gasket failure on JowettGallery
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