problems following overheat.

[Gosub]

Hi Guys,

My run of bad luck seems to be ongoing. I'm on my third engine in 6 months, the original blew an oil pump and fried the crankshaft etc, the rebuilt engine failed after the wrong main bearing shells were supplied and not checked before fitting.

My current problem started 2 days ago when the engine overheated. I turned the engine off as soon as I saw the needle at 220. I had the boat lifted boat and the lower outdrive pulled off. The impeller had seperated rubber from metal core. All the plastic tubes inside the drive were melted. After the repairs and launch the engine started fine and the temp stayed low.

The engine is running fine but now there is a white foam forming in the rocker cover on the starboard side. Water ingress! The oil in the sump is fine, no sign of water there.

My question to those in the know is: what is the most likely culprit... head gasket?. My Mechanic says it might also be a small crack in one of the manifolds. Would this allow water into the oil? I don't see how it would. I know a compression test is the first step, but would this show anything if there is a head gasket leak from water to oil side?

Engine is Merc 350 with alpha1 ser2.

Thanks
Steve.

 

[Failproof]

Re: problems following overheat.

How much white foam? If its true water ingress then its in the sump even if you dont think it is. A slight amount of slime is common on the filler cap if condensation is present, especially after rereaching 220 degrees and turning any water into steam.

 

[Gosub]

Re: problems following overheat.

Not a lot on the cap, but I can see quite a bit around the valve spring.

 

[Failproof]

Re: problems following overheat.

Its possible that condensation formed, and then the action of the spring emulsified and frothed the oil up, and it is clinging to the spring. If you have water in the valve cover/head area then its in the pan. Sounds like its not that bad. If all the oil is foamy; well its more severe! Its also possible that the seat pocket has a hairline fracture, alowing steam to escape, and cause the foaming. Is it multiple or just one spring? I have seen head cracks so small that it didnt leak persay but it would vaporize as it exited under pressure. Not really a plausable if running open cooling.

 

[Scott Danforth]

Re: problems following overheat.

if its just a bit, could be condensation. I recommend running it until its up to temp for a bit and monitoring. if your oil level starts going up, you have a leak into the block

 

[Gosub]

Re: problems following overheat.

It looks like the foam is coating the top of the head. I haven't taken the covers off yet. I'm still trying to stop myself putting a match to the biatchh.

 

[Failproof]

Re: problems following overheat.

Really check the oil, sounds like alot of condensation, but its possible.

 

[Gosub]

Re: problems following overheat.

OK, I just had it out on the Mediterranean for a few hours of fun. The engine ran like a dream, no steam, no smoke. However, looking in through the oil filler it looks like a Christmas postcard for mechanics: white everywhere. The dipstick still looks normal, no sign of anything but clean clear oil, at the same level as when I set off.

If this is actually water ingress, I go back to my original question. After a severe overheat... head gasket? Manifold? or worse? (insert scary music clip here)

 

[Bondo]

Re: problems following overheat.

OK, I just had it out on the Mediterranean for a few hours of fun. The engine ran like a dream, no steam, no smoke. However, looking in through the oil filler it looks like a Christmas postcard for mechanics: white everywhere. The dipstick still looks normal, no sign of anything but clean clear oil, at the same level as when I set off.

If this is actually water ingress, I go back to my original question. After a severe overheat... head gasket? Manifold? or worse? (insert scary music clip here)

Ayuh,.... It's probably condensation,... Run it, Hard, 'n up to temp for awhile, 'n steam off the condensate...

 

[Scott Danforth]

Re: problems following overheat.

post a pic if you can.

 

[Gosub]

Re: problems following overheat.

I had her out twice yesterday. Total run-time was about 2 hours. The problem seems no better or worse. The oil on the dipstick looks and feels like the new oil it is.

It has been suggested to me that, since this is a newly rebuilt engine, a re-torque of the head bolts might help.

Picture as suggested...

 

[Failproof]

Re: problems following overheat.

I dont see how, with that much emulsified oil on top of the head, that it did not mix with any of the other oil. You can see some oil flowing through the sludge. Its possible that no "new" water was added after the first leak. Maybe from a manifold leak, or a tiny crack, or a porous block casting(have seen it). Flush that junk out, and use fresh oil. See if it happens again. If yes, then there is an issue. Best way to get all that out is to remove covers, and vacuum it off. Then use towels to soak up any remaining sludge. It will not take much sludge to ruin the fresh oil. Big place to clean is the baffles on the valve cover. They will trap a crap load of junk.

 

[Stamey]

Re: problems following overheat.

I'd sure be tempted to pull the drain plug to see what runs out. That emulsified mess may be in the bottom of the pan now, where the oil pickup is, and you just can't see it on the dip stick yet because the dipstick doesn't go down that far.

Chris