Engine and Transmission Tech

As part of rectifying my strange carburreter problem, I need to reseal the inlet manifold.
The Haynes manual says 'apply sealant'.
Other pundits say don't, or disagree about which sealant and where to apply it.,

Rolls Royce, on the inlet of the Shadow (my current daily drive) used a sealant plus a silk thread around each port.

There's also disagreement about the gasket - steel or composite.

I probably lean towards Red Hermetite on a steel gasket.

What do you use?

Ivor

The black RTV seems to be pretty good, it is designed to be oil resistant.

Jim

My opinion would be a composite gasket and no sealer.
And here's why.
On an aluminium engine there is a tremendous amount of movement as it goes through it's heat cycles.
A steel gasket can't keep up with the expansion ratio. If it's glued down it just gets worse.The gasket gets torn up and walks out of the joint.
A composite gasket is a much closer match to the aluminium. And without sealer it can move with the engine as it's designed to..
There are times when a sealant has to be used. Such as at the water ports if the surface is not perfect.
Silicone at the water ports is acceptable if used "very sparingly" or better, is Permatex aviation sealant.
But only if you have to.
Sealants that harden have no place on an aluminium surface.
The silk thread application is an old aviation requirement. But it is still a very good method of sealing two machined surfaces.
It wasn't intended to be used with gaskets. Only on finely machined surfaces.
So there you go. Another opinion.

Live like you mean it
Fred

What sort of silk thread please?

Jim

The gold shiny stuff looks nice.

Seriously, it's generally a 00 silk thread that you would find in any sewing notions store.
It's applied in two runs and held down with permatex #4 to be certifiable If I remember right.
But gaskacinch or spray gasket adhesive work well also. (as long as it doesn't leave the ground!)
The intent is to provide an intense high pressure sealing area on two flat precision machined surfaces.

Cheers
Fred

"On an aluminium engine there is a tremendous amount of movement as it goes through it's heat cycles.
A steel gasket can't keep up with the expansion ratio. If it's glued down it just gets worse."

Sorry, but you need to do the math. The difference in thermal expansion over the small distances on the gasket are negligible. There were 750,000 215s built by GM and about that many built by Rover. They all came from the factory with a steel shim gasket and no special handling/silk thread or whatever. The RTV sealer isn't a "glue" anyway, it is FAR more compliant than either the steel or aluminum. Again, calculate the differential thermal expansion. You'll find the number is so small you won't worry about it.

By the way, since the steel gasket seals the valley of the block, how do you not use it?

Sorry,
I didn't know that this was such a touchy subject.
I gave my opinion, for what it's worth. Based on 39 years of experience, an engineering degree, a chemistry background, countless engine builds, aircraft motorcycle and racing experience, automotive awards world wide and the love of my mom.
I did "do the math". And according to my CLTE table it works out to a 0.004" expansion differential over the length of the engine @ 190'f.
Like it was said, not much, but enough to walk a gasket out of a joint over time. We've all seen a steel gasket shuffle around enough to tear out it's bolt holes and fret the aluminium.
Steel gaskets were the only thing available back in the 60's, and sealing technology has come very far since then.
I think it would be prudent to use the best technology available to seal your engine.
RTV sealants are very compliant and useful under the right circumstances. But they are generally miss used and over applied.
Applied to a modern gasket they defeat the purpose of the encapsulated compounds built into the material. And in some instances attack the gasket itself causing early failure. Not to mention the number of parts destroyed by loose pieces of silicone clogging them up.
The right type of silicone (there are many), under the right application and in the right amount is absolutely useful. Just not on everything.
I have a composite valley gasket in my hands right now. And to me it's the only way to go. No more leaks and it muffles some of the valvetrain chatter.
So that is my opinion.
Take it or leave it.
Just don't criticize it.
It's mine and you can't have it!

Cheers
Fred

Would you mind sharing the manufacturer and part number for the 215 V8 composite valley pan intake gasket please?

Just look for the "Land Rover Genuine Parts label.

(Easy to find. Expect to pay about $50. Not cheap, but definitely nice to have.)

Definitely the right part for the job. Almost bulletproof. Rover really did their homework on this one.

Jim

When you care enough to spend the very most...

All I can say is that I've had 215s since the early 1980s and never had an intake gasket sealing problem with the stock gasket. My friends with Jetfires similarly have had no sealing issues, even with boost. I've got lots of other places I'd rather spend that money. Your dollars, your call.

Plus, it doesn't rust and always looks good. :-)

Their stainless multilayer exhaust gaskets also are quite exceptional. (also quite expensive) Buy them once and never have another exhaust leak, and never buy them again. I even modified them to use on the 300 heads on my 340 when I upgraded from the 215. They are worth the money. Maybe not if you don't plan to keep the car but if you do, definitely a solid investment.

Jim

Surprisingly, the best price is from the dealer. Part # LKJ 500020 $25.10 can.
Felpro lists it as part # MS 97186 $54.80 can.
I'll second the MLS exhaust gaskets. Never had one fail.

Cheers
Fred

"Their stainless multilayer exhaust gaskets also are quite exceptional."

Just so I have this straight, this thread advocates using the composite gasket over steel on the intake side due to differential thermal expansion, but it's preferred to use the stainless gasket on the exhaust side where the differential thermal expansion is GREATER....

Just sayin' ;-)

My reasons for preferring the composite valley pan don't have anything to do with thermal expansion. It's just a better gasket, it's better looking, and I believe it to be a little quieter.

I have both. I agree with Curtis, Fred, & Jim.

The story I got was that when Rover upgraded the engine (and I can't tell you if that was when they went to the 3.9, the concentric oil pump, or at some other point) they also went through an intensive engineering review of all the engine sealing elements for emissions purposes. The results of that review included the new valley cover/intake gasket and the new exhaust seals. I decided to try them since these had always been two problem areas for various reasons. At the time the intake gasket was about $40 US which was a bit much but it sealed well all the way around and the engine stayed cleaner and looked better. Yes, I know the old tin cover does the job. But this one does it better. Worth the extra? That's up to you but I'd use it on any BOPR I built. The mild surcharge is nothing over the life of the engine.

As for the MLSS exhaust gaskets, the only thing I've seen to date that even comes close are the ones used by BMW, and I'll tell you something else too. MLS is fine but is woeful compared to MLSS. And most everything else is woeful compared to MLS. The stainless retains it's springiness through all the heat cycles, and it is easy to clean up back to original condition with a just rotary wire brush.

I never considered thermal expansion (TE) to be an issue with intake gaskets. I've never had a confirmed issue with port or water passage sealing. But sealing around the lifter valley has always been something of a challenge, and rust has been a cosmetic issue. I'd just as soon not deal with those sort of problems.

Jim

Although sometimes made from the same materials.
Single stage steel gaskets don't tolerate movement well and deform.
MLS gaskets are made to accommodate a degree of movement within their layers .
Unless made from stainless they are almost always coated with some form of solid lubricant and sealant.
The layers are made up of a minimum of three to allow them to slide freely across each other.
The layers also make up a very structurally rigid gasket that holds up well under extreme pressure.
MLS gaskets don't work everywhere but when used in the right application. Generally high heat and pressure. They are very hard to beat.