advice before disassembly of engine

[foresteronw]

I have a 1989 Sunbird Eurosport with an OMC 5.7L engine(original). I bought the boat last year and it hadn't been used all that much. The heads had been redone in December of 2001 and the owner had only put on about 10 hours since then. I bought it late last year and developed a water/oil mis problem. I was pretty sure it was my exhaust (manifolds/risers). This year I took it out to make sure there weren't any other problems with the boat. It started up fine and idles fine. In nuetral it will rev up to higher RPM fine. Once it is in gear I was not able to get it over 2700 RPM. I checked all the electrical system to make sure it wasn't messed up that all checked good. Again after several tries to get it to plane of and failed I tried reving the engine, again it reved fine. Idles great. I tookd it back to the dock puzzled when I got there it then had the oil/water mizture coming out of the breather tubes on the valve covers. <br /><br />I am going to tear down the engine this weekend to try and find the problem. I have been told it sounds like a crack somewere. The only reason I have my doubts about this is due to the fact that it happened all at once and that it runs fine unless it is under load. Please tell me if I shouldn't tear it down, or if I should. Also any pointers or hints that I should do before tearing it down that will help in the long run. Thanks

 

[snapperbait]

Re: advice before disassembly of engine

At least a compression test first... I can't offer much here other than, if you do tear into it, on re-assembly use the best gaskets you can get hold of, and (very important and often overlooked) brand new cylinder head bolts... <br /><br />Also, run a tap into each of the cylinder head bolt holes in the block to "chase" or clean them out... Don't neglect doing this becasue it can come back and bite you later on... Good torque values depend on good clean threads on both the bolts and block...<br /><br />Might take the heads to a machine shop to ensure the head surface it true and magnaflux them will help find any small cracks... <br /><br /> Torque the heads in three steps like 25ftlbs. then 45ftlbs. and finally 65 ftlbs., and in the proper bolt pattern...<br /><br />Do everything by the book...

 

[foresteronw]

Re: advice before disassembly of engine

Do you have any idea what I should be looking for when I tear down the motor. Will cracks in the block be obvious? If when I tear it down I can't find anything obvious what should I do next?