griffith 500 Exhaust blown manifold gaskets

[waggy]

1994 Preserp 500HC

Last summer on way back from Lincoln on our annual Tvr trip, my exhaust blew the manifold gasket on cylinder 2 of the r/h bank.

I managed to replace the gaskets and had trouble realigning the Y piece of the exhaust with the Manifold. after a struggle, I eventually got it together using 2 mole grips.

last week i started the engine after a month's break and the manifold gasket has blown again on cylinder 2. I think the problem is there's too much strain on the exhaust manifold from the Y piece trying to pull it away from the manifold, is this normal and is there a way to stop this?

any ideas appreciated

Alex

[Belle427]

May be worth checking the manifold faces are flat and not warped, if they were done up tight before installing the y i doubt very much they are being lifted but you never know.
Bolts loosening off can also be an issue and is more common.

[Loubaruch]

Although for a Serp engine you may find some of this of use:

http://www.bertram-hill.com/replacing-exhaust-gask...

[waggy]

The Bertram Hill site is quite informative. I tried loosening the manifold bolts whilst lining up the y piece but there was still quite a gap and still had to use 2 mole grips to force them together.

[Belle427]

Personally i think with that much stress on the joints something is bound to give but im not sure what the answer is apart from new manifolds etc.

[indigochim]

I had numerous attempts at stopping mine from blowing before Ian at TourqueRVT (RIP) pointed out that they where warped. After getting the surface linished they sound great and no leaks.

[Belle427]

Maybe a skim off them would help the alignment in this case.

[LLantrisant]

you need a skim on the face manifold to head.

if the manifolds do not fit on the y-piece and you need to force them..the longterm damage here would be a cracked collector (the parts where all the 4 pipes join in 1)

[Classic Chim]

It’s long since been documented when reconnecting Y piece to manifolds one or other will not line up. Given the manifolds left loose can move quite a bit it stands to reason bolting them tight independently, they are very unlikely to be in exact the same position relative to eachother. Usually you can just loosen one set of manifold bolts which allows enough movement to connect Y to the tight manifold then manipulate the loose manifold until it lines up with the Y and put clamps on.
Good practice is to loosen both manifolds, line Up Y piece and put clamps on both sides but not to tight then systematically tighten manifold bolts to heads then finally nip up V clamp bolts.
It’s long since been known even using this technique some Y and manifolds just simply don’t line up very well and using a ratchet strap usually pulling both manifolds towards eachother is the last resort but done this way since time began.
It’s not always the case that manifolds need skimming as this is an issue fitting almost all manifolds and my cars manifolds only came off the car for the 1st time at 40,000 miles and on original gaskets and re fitting them and Y piece was exactly as described by many others long before I did it.
There is a nack the pro’s use and ive just described it;) there may be other solutions but the one above has been done hundreds of times by dealers and owners alike.

[waggy]

thanks for the advice.. maybe my head's exhaust face needs skimming but its a big job removing heads..

I like the idea of using a ratchet strap to pull manifolds together. I'm worried that something might break..

will try the ratchet strap and see what happens..

thanks

Alex