Overheated 1979 4932D

[skybolt_1]

I recently replaced my water pump on a 1979 4932D, and everything was working fine up until last night.... Ran through some weeds and apparently partially clogged up the intake.

About 15 feet off the dock, the motor stalled out. Turn around, smoke everywhere, stinky gray smoke. The outside engine housing (frame) was too hot to touch. Got it off the boat, cleaned off weeds and pulled lower unit. Water pump looked OK, impeller wasn't damaged. There was a white, foamy, greasy coating all over the inside of the lower unit and shaft housing. The powerhead does not appear to be siezed - it turns freely. Pulled off the powerhead plastic skirt and checked for visible damage. Didn't see any melted parts or anything.

It sure smelled like something got badly burned out. Should I try starting it again or should I tear it down to see what got cooked?

 

[ezeke]

Re: Overheated 1979 4932D

Check your gearcase lube first.

 

[F_R]

Re: Overheated 1979 4932D

Any motor that has been run stinky hot needs at a very minimum to have the head gasket and exhaust gasket replaced becase they'll leak and admit water into the engine. Speaking here of the exhaust gasket under the flat plate on the side of the powerhead. While that plate is off, you can see the sides of the pistons through the exhaust ports. If they are scuffed up, that's a big bad.

 

[skybolt_1]

Re: Overheated 1979 4932D

I really need to remember to subscribe to these threads.... otherwise I forget to check!

OK: Lube was fine. Motor runs, albeit badly. Haven't had a chance to take it apart and check the piston heads. If they are scuffed, would it be considered worthwhile to rebuild the engine, up to and including honing the cylinders and putting in new pistons or would it probably be cheaper/less hassle to just purchase a newer used Tohatsu or something...

Keep in mind that this engine has been used extensively in salt water... there is corrosion on the non-aluminum/brass parts like the exhaust tube/ certain bolts.

 

[Paul Moir]

Re: Overheated 1979 4932D

Go ahead and replace the head and exhaust cover gasket like F_R said. They're both extremely cheap and that white froth you saw is indicative of water getting into one or both cylinders. Naturally, water in the cylinders will make the engine run bad.

After that, you can assess the damage. Rebuilding would be pretty expensive - at least $300 I imagine. An ebay powerhead or whole new outboard makes more sense usually. Fortunately these little guys seem to take overheating well.

 

[skybolt_1]

Re: Overheated 1979 4932D

Will do.

Thanks!