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Head Gasket?


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Hi All.

I'm the least mechanically minded person on this forum without a shadow of doubt, so please forgive me this essay, but I think it may be necessary to reveal my present problem...

My 1971 TR6 developed a bit of a misfire, a few months ( but to put that in context, I've probably driven 30 miles or so) ago. I thought I may have had an injector issue, and rather than 'fanny' about, I had Neil Ferguson refurbish all six.

That didn't cure the misfire, and due to the winter being upon us, The car has remained in my garage.

I gave it a bit of a run at the beginning of November and other than running a bit 'lumpy' she performs well over 40mph.

Since then I have fired her up in the garage, and let her tick over for 10 mins or so.

Today, I started her up, and let it run for maybe 15 mins?

To my horror there was a pool of coolant under the car ( less than half a pint) so I switched the engine off immediately.

Upon inspecting the radiator (stone cold BTW) I noticed that the reservoir was overflowing and was the source of the fluid now pooling on the floor.

I left it for an hour or so, then started the engine again.

Let it run for about 5 mins whilst keeping a close eye on the temperature gauge.

It quickly became apparent ( as the gauge didn't move ) that the radiator wasn't getting even warm, so I switched the engine off.

I have deduced ( after researching hours of you tube videos, and some great telephone advice from a forum member) that I may well have a problem with the cylinder head gasket?

The car has never lost so much as a drop of coolant, nor has it ever overheated. Other than the misfire, it was running, and sounding in rude health.

So my question is, could the misfire be related to the problem which has presented itself today, and why would a head gasket fail in the first place?

Bearing in mind that the car has never overheated ( in my 3 year ownership )am I likely to have done any damage to the engine???

Also, I'm guessing this is going to be expensive to fix?

Regards

 

Peter

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Peter,



Yes it might be a head gasket but then it could be so many other minor things as well. Leaking or loose hose or water pump for example.



As there is no oil / water mix. Get a really bright torch and perhaps a mirror. Then I would suggest filling radiator again and starting car with radiator cap on and letting tick over for perhaps 4-5 minutes to allow the system to pressurise even perhaps with trapped air. Keep squeezing the top radiator hose until you feel it start to pressurise then stop the engine.



Work your way around the head looking for a leak. Once you know with certainty where the leak is coming from then you are in a better place to decide what the problem is.



Caution, the engine does not bleed air from the cooling water easily. Usual way is with the rad cap off until trapped hot air is expelled. This may spray boiling water over you and it can give serious burns. If you are not used to cars take a great deal of care if the radiator cap is off.



​Alan


Edited by barkerwilliams
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Hi Peter,

if it is the head gasket will you be able to fix it?

If not then contact the garage of your choice and ask them to diagnose the problem.

They can test the radiator water to see if there is combustion gases in there.

They can do a pressure test on the combustion chambers and or a leak down test.

 

If the gasket has popped then you may (if unlucky) need the head and or block skimming

 

If you are able to fix it yourself then get a compression gauge and test kit and start the testing.

 

Roger

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Hi Peter,

depending where the gasket has failed it could cause all sorts of odd running.

 

One good thing though - if it is the head gasket and it is coincident with a water way the piston and combustion chamber will be nice and clean :)

 

Roger

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Hi Peter,

 

when you say the coolant was coming out from the reservoir do you mean the overflow bottle on the lhs of the radiator?

 

What psi is your radiator cap and how old is it?

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I'd be checking for an airlock around the thermostat first, even to the extent of removing the thermostat and seeing if the problem goes away. There are posts on how to fill the radiator and clear airlocks on this site. If you attempt to clear airlocks don't forget the heater should be turned on to maximum heat.

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I'd be checking for an airlock around the thermostat first, even to the extent of removing the thermostat and seeing if the problem goes away. There are posts on how to fill the radiator and clear airlocks on this site. If you attempt to clear airlocks don't forget the heater should be turned on to maximum heat.

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Hi DRD

The car underwent a full restoration three years ago, just before I bought it.

So I'm guessing the cap is in good working order?

The cap has LBS 13 stamped on it if that makes any sense?

Yes the reservoir bottle.

Yes it does sound like the gasket has blown then, the leak is pressurising the coolant and pushing it out the rad cap. Was there lots of steam in the exhaust? A compression test will show for sure and identify which piston it is.

 

I wouldn't drive it anywhere if it has gone though.

 

Darren

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It could very well be be a closed-stuck thermostat, since the radiator remained cold.

That would result in boiling coolant in the block, and the steam bubbles then push the radiator valve open and the bottle overflows.

If the radiator is indeed cold after 10-15 mins of running I would check that first.

Good luck,

Waldi

Edited by Waldi
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It could very well be be a closed-stuck thermostat, since the radiator remained cold.

That would result in boiling coolant in the block, and the steam bubbles then push the radiator valve open and the bottle overflows.

If the radiator is indeed cold after 10-15 mins of running I would check that first.

Good luck,

Waldi

Good call Waldi

 

Suggest removing the thermostat, replacing the cover and see how it runs.

 

If this is challenging for you then rope in a local TR Register member to help, i’m sure many would be willing !

 

Or, take it to a friendly garage for testing properly.

 

Steve

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If you can (feel up to it), remove the thermostat, put it in water, and bring the water to boiling point.

It should open before boiling at around 80 degrees.

Replace gasket by new one.

Note orientation of thermostat before removal and re-install in the same orientation (assuming it was installed correct since the car did not overheat in the past.

Look at the Moss website, here you can see how the parts look like if you want to do this yourselves prior to beginning.

It is a relative simple job.

Work on a cold engine and remove battery earth connection dor safety.

The workshopmanual gives a step by step explanation.

Regards,

Waldi

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Thanks for all your advice. I'll take the thermostat out tomorrow and report back.

I'm sure I can just about manage that - surely?

My lack of knowledge stems from driving company cars since '76 and unlike my pals that 'tinkered' with their cars every )weekend (as I laughed in the background) I never learned the basics of car maintenance.

Who's laughing now?!

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It could very well be be a closed-stuck thermostat, since the radiator remained cold.

That would result in boiling coolant in the block, and the steam bubbles then push the radiator valve open and the bottle overflows.

If the radiator is indeed cold after 10-15 mins of running I would check that first.

Good luck,

Waldi

Waldi, surely the temp gauge would go up into the red and overheat in that case.

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I have cured that befroe now by running the engien and thumping the thermostat housing with a leather mallet. A wooden one would do I guess. Massaging the top hose to dislodge air bubbles in thermostat might help too.

Peter

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Take it down to Birkenhead Engine Parts & repair in Cleveland St and ask them to have a look at it for you. They rebuilt my engine for me, though I've not run it yet, but they have done other jibs for me with no problems.

Other than that you can run it down to me and I'll have a quick look at it for you.

 

Jon.

Wallasey.

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Take it down to Birkenhead Engine Parts & repair in Cleveland St and ask them to have a look at it for you. They rebuilt my engine for me, though I've not run it yet, but they have done other jibs for me with no problems.

Other than that you can run it down to me and I'll have a quick look at it for you.

 

Jon.

Wallasey.

I'm in Eastham, so may well call in there. Thanks.

Edited by pjc615ukuk
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i'm with Waldi re the thermostat. Especially after standing for a while.Mine has done this 3 times after a lay up.I notice that he dose not say what reading on the temp gauge.

Also check the rad cap is long enough to seal and the rad neck top is flat there by giving a good seal.

 

ROY

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