OVERHEATED HEAD & CYLINDER PICTURES. HOW MUCH TROUBLE AM I IN???

[bobgritz]

I'm a commercial clammer and we go out 365/7 weather permitting. After irregular high tides the bay has random floating salt marsh hay and I managed to snag enough which covered my water intake for no more than 30-45 seconds. The engine stalled and was red hot to the touch. After cooling off it reluctantly ran but not well and compression measured 60 top and 30 bottom. I pulled the head hoping to just replace the gasket and maybe re-plane the head. Correct me if I'm wrong but the head appears to be junk and obviously the pistons should be replaced but if I can get 75+- pounds in top and bottom it will be fine for my use (our motors have a tough life and need overhauls every couple of years). The cylinder walls looked ok. My question is ... can I just replace this head and get away with the scorched pistons? I don't need stellar performance but I also don't want to waste more time and do something evil to the rest of the motor without knowing it. I'm using a similar (15 HP) backup motor that will probably find its way onto my workbench fail in about 2 years but I just need to get this one back on it's feet so it can be ready to come off the bench when needed.

 

[racerone]

Looks like some bits of metal went through the engine.------Take it apart now for inspection.--------How big is the boat / load here.------What pitch prop is on the motor ?

 

[Georgesalmon]

At the very least, I would, replace the head, hone the cylinders, new rings and pistons.

 

[F_R]

That motor has puked it's guts. Can't tell which gut without taking it apart, but no matter it must come apart anyway. If it isn't already totally destroyed, it will be if you keep running it.

 

[Bosunsmate]

Sorry to say that it looks like a major. Ive never seen one with all four pistons pitted, i suppose thats because ive never seen one get red hot, even one that was a run away and dieseling.
Was your overheat alarm not working?

 

[nphilbro]

Looks exactly like my 200hp V6 meltdown a couple years ago. I'm not sure if it was heat first/ring second but it got so hot it scorched the cowl. I removed the head and a ring on the stbd side had broken loose and punched the head. All three cylinders on that side were damaged. In my case, after a tear down I researched parts cost and the time involved in a rebuild I quickly discovered it had become a parts motor.

It will probably be a considerable time and cost savings to find a cheap used 9.9/15 in a year that matches the exhaust format (usually there are at least 3 years similar) the owner is getting rid of because it's incomplete or bad lower unit...or something like that as long as you can determine the compression is ok. All you need is the powerhead anyway and it's a relatively simple switchover, faster, easier, and cheaper than crankcase breakdown. I have a couple orphan power heads in my shop I'll probably drop onto a rebuild someday, they are pretty common to find.