News:

Due to a technical issue, some recently uploaded pictures have been lost. We are investigating why this happened but the issue has been resolved so that future uploads should be safe.  You can also Modify your post (MORE...) and re-upload the pictures in your post.

Main Menu

Cracked LH exhaust manifolds on 70's cads & maybe others?

Started by TJ Hopland, July 29, 2007, 02:09:09 AM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

TJ Hopland

I am almost done installing a rebuilt engine in one of my 73 eldos and got to the point of taking the exhast manifolds off the old motor to the machine shop.   I discoverd 3 cracks in the left one.  I knew it had a leak but it looked like it was a gasket.  No problem I had like 6 spares that came with the car when I bought it 12 years ago.  All the rights are fine, lefts are cracked.  No problem I have 3 more fairly complete cars...  all but one cracked.   Went looking and right ones can be had for $50 or less and everyone has them.  Left ones for eldos or rwd cars seem to be scarce and if they are around they seem to be worth much more money which would lead be to believe that they must all crack on the left side for some reason.  In 3 out of my 4 eldos that I was able to look at I noticed that the left exhaust pipe is touching the left torsion bar including the one with the non cracked manifold.  None of mine have what I would call a factory exhaust system so this could explain why mine are all cracked but I would not think that all of them out there have the same bad systems on them that mine have.   And then how do you expain the RWD ones?  On my 78 the cross over pipe runs over to the right side and then back so you would think that the right side would have more stress on it.  I have heard on some cars water splashing on the manifolds crack them.  On the eldo's the left manifold would be protected by the transmission so this doesnt make sense either.

Anyone else notice the same thing and have a theory?
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

35-709

Exhaust manifold cracking seems to be a pretty common occurrence, at least on the ones I am more familiar with, the 390's and 429's.
I have always laid it to two things (this falls in the personal opinion category), the factory's practice of not using gaskets and mounting them "metal to metal", and engine overheating.  Cold water splashing on a hot manifold also sounds plausible, but I feel it all still falls back to the metal to metal mounting which doesn't allow any "give" necessary because of different rates of expansion and contraction.

BTW, don't throw out those cracked manifolds, a good welder can repair them.  Unless of course they get broken completely trying to get them off the car.   :( 
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2