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View Full Version : Corosion in the exhaust manifold


Stephane
05-09-2004, 09:33 PM
I have a Ragazza 23 1988 with a 350 OMC. I removed, clean and re-install the exhaust manifold with new gasket last week-end end. The inside of the manifold was full a rust and chunck of corosion, i cleaned that but the problem now is a leak of water by the flenge. Is it possible to regrind or rebuilt the flenge for a better contact or do you know some other trick to fix this problem ?


Thanks
McGary911
05-09-2004, 10:27 PM
When it gets this bad, you had better start saving for new manifolds. Can you fix the flanges? yes. I did this on my big boat 2 years ago, and theyre still fine. I had to cut about 1/8 of an inch off of the flange, which i did on a bridgeport milling machine. This way i kept the surface perfectly machined, and it sealed up like new. I'll probably have to buy new ones this year, but i bought some time. If i didn't have a friend with a machine shop, i would have just bought new manifolds.
MOP
05-10-2004, 07:48 AM
The flange area seems to get bad first, yes they can be cleaned up and resealed. It is only a stop gap measure for another season or two. One thing that does slow this process down is to use the blocker plates and good sealers, I have noticed over the years that manifolds with blocker plates do not corrode as bad at the mating surfaces as bad as those without plates. Another major plus is riser plates rarely allow water to leak into the engine, many an engine has been ruined by leaks at the riser gasket. With the price of replacement manifolds coming down it may be more prudent to chuck any iron that is questionable. Almost all manifolds have the provision to use block off plates, I try to talk all my friends and clients into using them.

Phil
bigman
05-10-2004, 10:45 AM
I have changed the manifolds on my 350. It is a 2001 engine. The manifolds I have only have about 30 hours on them. It's the risers and the elbows. I don't have any need of them let me know if they could help, good luck big man.
Stephane
05-11-2004, 05:54 AM
Is it a Merc or OMC exhaust system ?





I have changed the manifolds on my 350. It is a 2001 engine. The manifolds I have only have about 30 hours on them. It's the risers and the elbows. I don't have any need of them let me know if they could help, good luck big man.