OMC 43 v6

"I recently had the exhaust ma

"I recently had the exhaust manifolds replaced on my v6 4.3 (1989). We fitted the Osco replacememt manifolds from Go2Marine in the States.After completion, I had water in the bores and it turned out that my engineer had fitted the gaskets wrongly. Another set of gaskets later (fitted correctly) and the engine ran perfectly in the yard (on the muffs)for half an hour or more. the next day, still on the muffs, the back 2 cylinders were wet again. My engineer now thinks that the cylinder liners have become porous, but I think that's a little too convenient. Possibly, the manifold gaskets are weeping again, but the faces seemed perfect and the bolts were torqued up correctly. Any ideas?"

"If your liners just become po

"If your liners just become porous (cracked), it is because you ran it with water in them. Do a compression check, it is possible you blew the head gaskes. The '89 OMC was a Cobra which used a one piece manifold, and does not have a riser gasket.

What gasket could he have installed wrong? Even if he used some fitsall manifolds, the gaskets are symmetrical, you can't put them on wrong.

What was the reason for replacing them? It sounds like you may have had a prior problem that changing the manifolds did not correct."

"Many thanks for reply. The ma

"Many thanks for reply. The manifolds used were Osco's 2-piece direct replacement for the original one-piece. Good picture and details at: http://www.go2marine.com/product.do?no=153929F

There is a gasket between the bottom half (against the head) and another gasket between the two halves (bit like a mercruiser 2-piece). It is this gasket that CAN be fitted 180 deg. the wrong way (which is what the engineer did). I sent awy to GO2Marine for second set which he then fitted correcty, but since then have had water getting into the back 2 pots."