Troublesome Head Gaskets - what Torque??

[OldBob]

Gents,

at 7k miles the head gasket was leaking at the rear, not terribly but enough to be a nusience and over the bellhousing so not good. Changed it to a new Payen one which was Wellsealed both sides & torqued to 80ft/lbs. Then engine warmed to operating temp, then cooled overnight and torqued again to 80 next day (about 10 more Lbs movement).

Now at 300 miles in the new gasket is weeping but not same place - along the plug side of the head. Thought it was the Wellseal at first but no, its oil.

Checked torque again and its still at 80.

The car is a CR but block has been decked so used a CP gasket (same as first one). Head was checked for flatness myself, no DTI available so used a flat steel edge.

Question is: Do I replace again with a better/different gasket that someone can recommend?   OR Torque a bit higher?  ARP studs and nuts are fitted.

ManyThanks

Bob

[Andy Moltu]

The left hand side of the head beyond the push rods is outside of the area that’s firmly clamped by the head studs so is always prone to leaking as that side also has the oil returning from the rockers.

Next time you have the head off you could try the following suggestion that was given to me: Check it’s not warped

Firstly it’s worth remembering that you need to get the head and block surfaces clean & grease free.

The head gaskets from the likes of Payen have a sealing “lacquer” already applied. This is more than adequate for the job around the cylinders and water jacket so don’t add anything to this area. However it won’t bridge unclamped areas, which is the leaky area. So in this area only, rub off the lacquer with fine emery paper to key the surface and apply a thin smear of a thicker gasket sealant such as Hermetite red or a quality RTV silicone. Wellseal is too thin for this purpose and not a good idea to use on a composite head gasket (Good to use on copper head gaskets on the 4 pots but not on the 4 pot composites, which again have lacquer and pre-applied heat activated additional sealant in key areas)

[roy53]

Bob payne gaskets do not need wellseal as Andy mentioned. 

TR Shop do a good quality head gasket ,composite type with an added red seal . Again no extra sealant required.

I have used both with good results.

Roy

[OldBob]

Thanks Gents, I'll have to put up with it for a while s have things planned but looks like it'll have to come off again then.

I'll get onto TR shop tomorrow about your head gasket recommendation Roy - can't see it on their website.

Cheers

Bob

[OldBob]

I'll just drop this link here to the uprated head gasket with a red RTV line that Roy has referred to above - found it on TR Enterprises website.

https://triumphspecialtuning.com/product/uprated-composite-cylinder-head-gasket-triumph-tr5-6/

Bob

 

[John L]

Don't forget that you must back off the nuts at least a 1/2 turn of the nut to relieve the stiction of the nut to the washer, before applying the new torque.

John

[astontr6]

On 5/27/2024 at 9:03 AM, OldBob said:

Gents,

at 7k miles the head gasket was leaking at the rear, not terribly but enough to be a nusience and over the bellhousing so not good. Changed it to a new Payen one which was Wellsealed both sides & torqued to 80ft/lbs. Then engine warmed to operating temp, then cooled overnight and torqued again to 80 next day (about 10 more Lbs movement).

Now at 300 miles in the new gasket is weeping but not same place - along the plug side of the head. Thought it was the Wellseal at first but no, its oil.

Checked torque again and its still at 80.

The car is a CR but block has been decked so used a CP gasket (same as first one). Head was checked for flatness myself, no DTI available so used a flat steel edge.

Question is: Do I replace again with a better/different gasket that someone can recommend?   OR Torque a bit higher?  ARP studs and nuts are fitted.

ManyThanks

Bob

Having worked on the original Head Gasket Tooling their has been a few errors stated. If the counter bores have been machined off that is a major cock up??? The whole point of the counter bores was to use a gasket with fire rings to give better sealing between the bores. To cure this problem. The original CP blocks and heads suffered from distortion in a big way. In the summer of 1972 mods were introduced to stiffen up the block and the cylinder head. The varnish applied to the head gaskets is silicone. It was put their to stop the head gasket sticking to the block and did not work on the TR7 but when still using asbestos it also cut down the amount of fibers floating around in the air, as there were now strict rules on this.

Bruce.

[OldBob]

9 hours ago, astontr6 said:

Having worked on the original Head Gasket Tooling their has been a few errors stated. If the counter bores have been machined off that is a major cock up??? The whole point of the counter bores was to use a gasket with fire rings to give better sealing between the bores. To cure this problem. The original CP blocks and heads suffered from distortion in a big way. In the summer of 1972 mods were introduced to stiffen up the block and the cylinder head. The varnish applied to the head gaskets is silicone. It was put their to stop the head gasket sticking to the block and did not work on the TR7 but when still using asbestos it also cut down the amount of fibers floating around in the air, as there were now strict rules on this.

Bruce.

Bruce, thanks for your message - what exactly are the errors though?

Bob

[astontr6]

26 minutes ago, OldBob said:

Bruce, thanks for your message - what exactly are the errors though?

Bob

Machining off the counter bores from the block face. I suspect that the block is not flat. The fire ring gasket seems to have a poor reputation on this forum. I have never had any trouble in 50 years. and I have a CR engine. In static tests that we did we could easily distort the CP block and lock the crank up. The CR block and head is much stronger.  The silicone varnish is not a gasket sealant. It is also used as an agent to make cyl. head removal easy, does not always work, eg TR7.

Bruce.

[roy53]

As re torque stopped the first leak and it has appeared in a different location i would try another re torque at a slightly higher torque.Say 85 lbs.

Have you checked your wrench against another to confirm that yours is reading correctly.

Roy

[JochemsTR]

with ARP Bolts and nuts installled, you need to torque upto 88 lbs in three steps.

[OldBob]

Thanks all for latest thoughts,  the performance head gasket with red silicon bead has now arrived (TR Shop) but I might as well try your recommended 85 / 88 setting Roy / Jochems as it could save a strip down before the Malvern show.  I'm not paticularly confident tbh now the oil has got into the joint but worth a try over the weekend.

Bob

[unclepete]

How did it go Bob?

Would be interested to see how a Head Retighten would go versus a new head gasket?

On 6/5/2024 at 8:18 PM, OldBob said:

Thanks all for latest thoughts,  the performance head gasket with red silicon bead has now arrived (TR Shop) but I might as well try your recommended 85 / 88 setting Roy / Jochems as it could save a strip down before the Malvern show.  I'm not paticularly confident tbh now the oil has got into the joint but worth a try over the weekend.

Bob

 

[OldBob]

57 minutes ago, unclepete said:

How did it go Bob?

Would be interested to see how a Head Retighten would go versus a new head gasket?

 

Hi Peter,

I tried the higher torque and as suggested on here I compared 2 wrenches to double check setting. I think there has been a slight improvement and it slowed it to a minor weep rather than a run - but its clear if I want a totally dry looking engine then will need to replace the gasket again.

Didn't have time before Malvern as car developed another couple if issues (don't they always) which I needed to deal with in order to do the trip.

On the winter jobs list now.

Bob

 

[Malbaby]

The problem may not be with the gasket or the bolt torque.

Since the block has been decked, by how much?.... I would recommend checking the combustion chamber volume to ascertain the current compression ratio....Higher the compression, higher the gasket failure rate.

Confirm the piston tops do not protrude above the block surface.

As already mentioned, check the cyl head surface for absolute flatness.

[JochemsTR]

I had my engine with a 10.5 CR which is exceeding the original spec by far. Those head gaskets do not care.

When block und head are flat, torqued properly in sequence and value you will not have a problem.

[Mike C]

You've probably checked for this, but your block was decked- are you sure that the cylinder head nuts are not bottoming on the stud threaded length?

[Samilenoble]

Hi

It must be frustrating after all that work to see it still leaking. If the Payen gasket is already leaking at 300 miles, even with the right torque and retorquing, I wonder if it is not a problem of compatibility with the bridged block, or of a surface not perfectly flat. Your check with a steel edge is a good move, but a more precise tool like a dial gauge could reveal small irregularities that go unnoticed.

To better diagnose if the head gasket is the culprit, you can also consult resources like What are the symptoms of a cracked head gasket?. It can help you spot other signs that confirm or rule out this lead.

For the gasket, you could try an MLS like those from Cometic, which are often better for demanding applications or modifications like a bridged block. As for torque, 80 ft/lbs with ARP studs seems fine if you use the recommended ARP lube, but going over that could warp the cylinder head.

Personally, I would have the block and head surfaces checked by a pro before taking it all apart again. Sometimes a small irregularity can cause this kind of problem. And if you are going to go back to a different gasket, a reinforced model would be a good idea.

 

Good luck, I hope it gets fixed soon!

[John L]

How is the crankcase vented, is it the small pipe on the steel rocker cover, with the flame trap?  I know that can restrict the airflow.

I understand that the crankcase can be vented via the lift pump blanking plate, with a much bigger pipe/hose, to a catch tank, that may be a better option?

The leak is thru the internal part/layers of the gasket material, if you do it again, I would consider putting some silicone on the inner edge of the gasket, on the outer slots of the pushrod holes in the gasket, that's where the oil is seeping thru.  Or perhaps filtering some super glue along the edge of the gaskets at those exposed to the crankcase pressure, that should also help to seal the fibres and stop the oil seeping thru,  just a thought perhaps.   If you do it next time, let us know if it worked......

John

[OldBob]

On 10/16/2024 at 6:22 AM, Mike C said:

You've probably checked for this, but your block was decked- are you sure that the cylinder head nuts are not bottoming on the stud threaded length?

Hi Mike, apologies for late reply - hadn't seen your post until tonight. Yes, I'm pretty sure there plenty of thread on the ARP studs to cope with the clamping.

 

2 hours ago, John L said:

How is the crankcase vented, is it the small pipe on the steel rocker cover, with the flame trap?  I know that can restrict the airflow.

I understand that the crankcase can be vented via the lift pump blanking plate, with a much bigger pipe/hose, to a catch tank, that may be a better option?

The leak is thru the internal part/layers of the gasket material, if you do it again, I would consider putting some silicone on the inner edge of the gasket, on the outer slots of the pushrod holes in the gasket, that's where the oil is seeping thru.  Or perhaps filtering some super glue along the edge of the gaskets at those exposed to the crankcase pressure, that should also help to seal the fibres and stop the oil seeping thru,  just a thought perhaps.   If you do it next time, let us know if it worked......

John

Hi John,

I do have a substantial oil catch tank on the engine of 3L capacity and its vented from the crankcase & rocker cover so I don't see how there could be build up of blowby pressure that could cause the leak. As for silicone sealants, yes I spoke to Enginuity about their method of head gasket assembly and they use WURTH RTV which I am likely going to use also. December is head off  month!

Thanks for the suggestions, Bob

[Kenrow]

19 hours ago, OldBob said:

I spoke to Enginuity about their method of head gasket assembly and they use WURTH RTV which I am likely going to use also. 

Did Enginuity have any other procedures other than RTV?