Replacing the manifold gasket

[Pete Bags]

Hello,

I think I have a small leak in my manifold gasket - at one of the exhaust ports. I am getting a 'ticking/clicking' noise when driving, no reduction in power, no increase in temperatures, and no 'mayonnaise' or signs of oil in the coolant. I noticed a tiny amount of soot residue on the manifold-to-head join (red arrow) which is also where the ticking noise seems to be coming from. So hopefully this is a blown manifold gasket and not a head gasket or broken piston ring!

As my 1098 engine has a LCB exhaust and mini inlet manifold, are there any recommendations as to which gasket is the best to fit?

Any top techniques for removing the existing manifold? I assume I will need to disconnect the water hose to the inlet manifold, but all and any suggestions welcomed. Anything to avoid yet more skinned knuckles...

Many thanks!

IMG_3994.jpeg (282 KiB) Viewed 1391 times

IMG_3993.jpeg (388.56 KiB) Viewed 1391 times

[philthehill]

One of the things that you must ensure is correct is that the outer faces of both the inlet and exhaust manifolds are at the same level. If they are not the thick washer will not hold the manifold to the head correctly.
In some instances I have had to insert a section of manifold gasket to bring the outer faces of the manifold(s) up to the same level. This is especially important when you have two separate manifolds fitted with the possibility of different flange thicknesses.
The manifold gasket needs to be smeared with grease. This helps bed and seal the gasket.
There is no easy way to remove either the inlet or exhaust manifold & gasket.
It is best if you disconnect the water pipes from the inlet manifold before attempting to remove the inlet manifold.
This manifold gasket is more than adequate:- http://www.minispares.com/product/Class ... o%20search

[simmitc]

Before taking everything apart, you could prove that there is a leak there with either some talcum powder or some soapy water applied over the area. Power blown away or bubbles forming will confirm gases escaping from that area.

[Pete Bags]

Thank you Phil-the-Hill and Simmitc for your thoughts - just what I needed, and another reason why this forum is so good!

[oliver90owner]

Before taking everything apart, you could prove that there is a leak there with either some talcum powder or some soapy water applied over the area. Power blown away or bubbles forming will confirm gases escaping from that area.

Spot on. Every time! Often only needs a simple check before doing any repair work

As PTH noted, the exhaust and inlet flanges, being of different thickness may need an alternative approach to making the repair. I expect I might well make some stepped washers for this sort of thing.

[Pete Bags]

New gasket as been ordered!

Just in case I use the wrong grease on the gasket, which grease can I use? I use MolyGrease general purpose lithium based for trunnions, UJ's etc, but is that suitable for the high temps on a manifold gasket?

Many thanks!

[philthehill]

Smear the gasket with Castrol general purpose grease or similar.

[Pete Bags]

Thanks Phil!

Today I removed the manifold nuts (they came off very easily) and removal of the old gasket proved to be trouble free. It's always nice when the issue is evident to see - the gasket had thinned out so the exhaust gas (and tell tale soot!) was easily visible.

Next job is to clean both all surfaces and put the new gasket (smeared with grease!) back on. Hopefully peace will return to the engine bay.

Thanks again for all your helpful comments - it makes Moggy ownership so much more pleasurable.

Some snaps of the faulty gasket:

[philthehill]

Well done.
Phil