water in oil OMC 351W...heads off, help!!

[danthern]

Water in oil 77 I/O omc 235 hp 351W. I'm down to the block, but I've never done this before, need a little diagnostic help... When I removed the heads, water was standing on top of the pistons...should this be?? The head gasket itself appears intact and I see no visible cracks in the block or heads, although I haven't had them magnafluxed yet. whats my next step? Are there telltale signs I should be looking for? Any help is greatly appreciated.

 

[ed hobbs]

Re: water in oil OMC 351W...heads off, help!!

Was there wate in all the cylinders or just some. Could be a cracked exhaust manifold breaching water into the exhaust chamber, and running into the open exhaust valve at shutoff. This would likely only be in a few cylinders though.

 

[danthern]

Re: water in oil OMC 351W...heads off, help!!

In every cylinder that the piston was depressed, water was standing....

 

[Solittle]

Re: water in oil OMC 351W...heads off, help!!

The heads & block may be OK. Possibly you ingested water through the exhaust. Did it get hot?

 

[danthern]

Re: water in oil OMC 351W...heads off, help!!

as a matter of fact, it did run hot....discovered I need a new impeller.

 

[akriverrat]

Re: water in oil OMC 351W...heads off, help!!

water on both sides either came up the tailpipe or down from above. crack in intake manifold or, as solittle was probably going to say, diesled backwards when you shut down overheated.

 

[danthern]

Re: water in oil OMC 351W...heads off, help!!

Thanks for all the advice...took the heads to the machine shop, no problems there, block looks good, head gaskets were intact so I agree that water probably entered through the exhaust. I keep hearing about the flapper....can someone tell me where that is and what I need to look for to rule that out (or in)? Will replace all gaskets on re-assembly including heads, manifolds and risers, which are less than a year old, but while everything is apart, I figure it won't hurt. that darn flapper thing has me puzzled. Thanks for the help, you guys are awesome!<br />Dan

 

[ed hobbs]

Re: water in oil OMC 351W...heads off, help!!

I'm not familiar with that year - mine's 10 years newer, but I think they are all similar. The flappers are at the top of the Y-pipe where the rubber tubes attach. Sometimes they burn up and fall off the pin, so when you pull off the tubes, all that is left is the pin. You need to make sure it is not stuck somewhere downline in the exhaust system.<br /><br />Also, before putting the exhaust manifolds back on, make sure they are not cracked and leaking. I found out how much water can leak into the cylinders . Hook a garden hose up to the inlet and turn it on. No water should be in the exhaust side.<br /><br />Is the water jacket clear of any blockage? Now would be the time to clean them out if you haven't ever done it.

 

[danthern]

Re: water in oil OMC 351W...heads off, help!!

Thanks for the advice.....the manifolds and risers are essentially new, gonna pressure test them anyway. let me make sure I get this right....where the rubber tubes connect the risers to the bell housing, is that where the flappers should be? There is nothing there, no valve, no pin, nothing....don't even see a place where a pin would mount. My OMC shop manual says nothing about the flappers that I can find. Also, can you get by with a automotive head gasket, or is a marine application a must?<br />Thanks,<br />Dan

 

[ed hobbs]

Re: water in oil OMC 351W...heads off, help!!

Like I said, mine is different year. My manual said nothing about them either. A nice mechanic asked me if I needed them when I was buying the other parts, otherwise I wouldn't have even known what that pin was for! I suppose for you they might be somewhere else, but I don't know where. Perhaps you can find a nice mechanic who can help you, too.<br /><br />I believe an automotive gasket will be fine for the heads, but ask your nice mechanic when you find him!

 

[akriverrat]

Re: water in oil OMC 351W...heads off, help!!

marine head gasket a must if raw water cooled in salt or brackish water. preferable otherwise. they use stainless steel on the marine.

 

[ed hobbs]

Re: water in oil OMC 351W...heads off, help!!

Good advice on the gasket, I've since learned! I have FWC.

 

[danthern]

Re: water in oil OMC 351W...heads off, help!!

Thanks fellows...I'll take your advice...now if I can just figure out where the flappers are....