Exhaust Gasket Sealant

[Martin S]

Looking to reattach tubular exhausts to heads. Will be using the 'tubular exhaust' gaskets from EJ Wards. What sealant (if any) is recommended?

[stagwingnut]

Never had to use on my tubulars , wait for others to comment, I wouldn’t consider using it myself . Regards Graham

[richardthestag]

on standard manifolds the gaskets started blowing within a 1000 miles on my stag, cannot recall where I got them from now. Might take me a day to dig through the boxes of receipts.

Date stamp on the image is June 2015

20150617_194452.jpg

I guess Wards gaskets are a lot more robust.

No they didn't blow when first fitted
Yes the threads were good for the manifold bolts
Yes the bolts were torqued up correctly.

My guess is that the heat/cool cycle coupled with some compression of the gasket caused a fixing to work loose and the blow to start.

For me though I generally avoid this upgrade* and stick with exhaust paste between the two smooth faces

[DJT]

I fitted Phoenix tubular manifolds back in 2014. Around a year later one of the gaskets on the RH side started to blow. Changing the gaskets in situ is a real faff, but I did it and added some exhaust sealant. When I overhauled the engine this year, I used exhaust sealant on the gaskets hopefully reducing the risk of having to wrestle with them again any time soon.

[jbuckl]

I tried the exhaust manifold gaskets. They were / are not made from the correct material afaiaa. They crush after a few heat cycles & allow bolt torque relaxation & blows.

[Martin S]

Thank you all. Appreciated as always.

[marshman]

I tried the exhaust manifold gaskets. They were / are not made from the correct material afaiaa. They crush after a few heat cycles & allow bolt torque relaxation & blows.

Exactly this. If you do use gaskets (with or without "extra" paste) it is worth rechecking the tightness of the nuts and bolt fairly frequently until they stop "crushing". I have had this on several vehicles using "newer" repro exhaust manifold gaskets. First one was on my Standard Vanguard a few years back, replaced 3 sets of gaskets before I realised what was happening. A recent rebuild of the cylinder head on my diesel landy 110 revealed nearly all the nuts were "slack" on the manifold (the manifold had been off fairly recently to sort a problem with the turbo). Since the rebuild I have rechecked the nuts - same time as retorquing the head studs - and hey presto amazed at how much more they tightened up.

Once the exhaust has started to blow you will probably find the gasket has started to break up where the hot gases have effectively burnt the gasket material. You may get away with a bodge of packing in some exhaust paste but ultimately it is manifolds off and start again - so check and check again.