Inlet manifold gaskets

[Millywiddy]

Hello Folks,
Can anyone help me with advice regarding the current thinking on Manifold gaskets,I thought that the Payen type with the water escape slot was the best choice but now I see SOC spares selling on Ebay saying that their yellow ones without the slot are better because the slot was a weakness.

Any help /opinion would be greatly appreciated as obviously the replacement is quite a bit of work and risk and I want to get this right,

Regards Julie.

P.S I have started pricing up Helicoil kits,what size is the bolt an which size helicoil ?

[nib]

Hi Julie
What I found was that my leaks on my previous inlet manifold were down to the manifold itself, I tried Payen and various other makes and the use of Wellseal and still had no joy but when I replaced the inlet manifold with a vgc s/h one and got my gaskets off Robsport it was fine, I just have to nip the bolts up from time to time if I see any traces of leakage.

[flying farmer]

The ones without the slot may be stronger in theory, but when they do leak the water is pulled straight into the inlet port by the vacuum generated by the engine on part throttle.

This is one cause of unseen water loss, when it gets worse steam can be seen coming out of the exhaust even when the engine is hot when on a trailing throttle.

The bigger problems occur when the engine is not running. The water then runs into the cylinder where it can cause huge damage due to corrosion when the engine is left un started for a while (during the Winter for instance). Over the years I have rebuilt 4 Stag engines I bought as non runners, and every one of them needed the cylinder liners replacing on one of the rear cylinders where water had got into the engine through leaky inlet manifold gaskets. It is not an uncommon problem by any means.

IIRC Stag specialists Faversham classics actually recommend draining the cooling system if the car is to be laid up over Winter for this very reason. They used to have pictures on their website of the mess that occurred when water did get where it shouldn't.

Neil

[milothedog]

Hello Folks,
Can anyone help me with advice regarding the current thinking on Manifold gaskets,I thought that the Payen type with the water escape slot was the best choice but now I see SOC spares selling on Ebay saying that their yellow ones without the slot are better because the slot was a weakness.

Any help /opinion would be greatly appreciated as obviously the replacement is quite a bit of work and risk and I want to get this right,

Regards Julie.

P.S I have started pricing up Helicoil kits,what size is the bolt an which size helicoil ?

5/16" UNC

[GDPR]

I make my own gaskets now from decent gasket paper - the quality and thickness is too variable now on the shop bought ones (and I include the water run offs)

[Millywiddy]

The ones without the slot may be stronger in theory, but when they do leak the water is pulled straight into the inlet port by the vacuum generated by the engine on part throttle.

This is one cause of unseen water loss, when it gets worse steam can be seen coming out of the exhaust even when the engine is hot when on a trailing throttle.

The bigger problems occur when the engine is not running. The water then runs into the cylinder where it can cause huge damage due to corrosion when the engine is left un started for a while (during the Winter for instance). Over the years I have rebuilt 4 Stag engines I bought as non runners, and every one of them needed the cylinder liners replacing on one of the rear cylinders where water had got into the engine through leaky inlet manifold gaskets. It is not an uncommon problem by any means.

IIRC Stag specialists Faversham classics actually recommend draining the cooling system if the car is to be laid up over Winter for this very reason. They used to have pictures on their website of the mess that occurred when water did get where it shouldn't.

Neil

Thanks for your intelligent answer Neil,and congratulations on the excellent thread regarding tuning of the Stag engine

[Millywiddy]

I make my own gaskets now from decent gasket paper - the quality and thickness is too variable now on the shop bought ones (and I include the water run offs)

That seconds Neils advice,thats sorted then,
Thank you Kryten

[Millywiddy]

Hi Julie
What I found was that my leaks on my previous inlet manifold were down to the manifold itself, I tried Payen and various other makes and the use of Wellseal and still had no joy but when I replaced the inlet manifold with a vgc s/h one and got my gaskets off Robsport it was fine, I just have to nip the bolts up from time to time if I see any traces of leakage.

Cheers Nib

[Millywiddy]

5/16" UNC

Hi Milo ,Thanks ,would I need to ask for a 5/16 unc helicoil?

Many Thanks

[jbuckl]

do repair the bad head threads with (as mentioned) 5/16" UNC helicoils or similar thread repair devices (time-serts are dearer)

make sure threads are spotlessly clean using brake cleaner & wipes / thread cleaning bolt / tap.

Use new bolts.

consider drilling the manifold bolt holes out to 9mm if its a non aligning manifold.

order 2 sets of gaskets or make some (!)

assemble with dirko (elring) or tiger seal (p.u.sealer) 1mm bead if you can, smeared thinly if you can' t!

leave to go off before refilling with coolant.

re-tighten bolts after warm up / settle

[edd]

I make my own gaskets now from decent gasket paper - the quality and thickness is too variable now on the shop bought ones (and I include the water run offs)

So true. My payan gaskets were different thicknesses even visibly. This would have caused a major fault.
Edd

[milothedog]

Hi Milo ,Thanks ,would I need to ask for a 5/16 unc helicoil?

Many Thanks

Yes if your repairing the threads in the heads that hold the inlet manifold on.

Ian

[DJT]

Check the inlet manifold gasket faces. These are often pitted and/or not flat. Pits can be cleaned out and filled with JB Weld, or similar, then flattened with careful use of a long file or flat piece of wood and glass paper. Dry fit the manifold and measure face gaps with feeler gauges to make sure faces are parallel. I've not noticed a problem with genuine Payen gaskets and used Wellseal with excellent results.

[Millywiddy]

Thank you ,jbuckl ,and DJT great advice,
I am grateful and feel more confident armed with practical knowledge and tips,

Thanks to all,
Kind Regards Julie

[richardthestag]

Payen Gaskets and wellseal is perfect for this.

If like mine you have installed one helicoil and it has gone a few mm below the head face so that one of the four long bolts only just reaches it you may curse. Help is on hand though. the long bolts from the carb inlet elbows are the same thread but crucially just a little longer