110 johnson won't start after overheating

[cosworthrs500]

motor is an '86 110hp johnson j110tlcdc. I had the boat out for an afternoon cruise yesterday, running about 4000rpm. On the way back moving with the wind I smelled what I thought was melting plastic. I peeked back and noticed smoke coming from under the cowl. I instantly shut off the motor, and cautiously raised the cowl with my extinguisher handy. no fire but any rubber or plastic components that was in contact with the heads were smoking/smoldering. I dripped some lake water off my hand on the head, and it sizzled as though it was a frying pan. After cooling down (about 45min)the motor could not be re-started, and we had to get a tow home. The wiring on the two temperature sensors is melted at the head, and the coils show some damage too. The water impeller was done last fall and the tell tale has been strong. Any ideas where I can begin??

 

[Daviet]

Re: 110 johnson won't start after overheating

Does the engine turn over, have you checked spark and compression?

 

[Chinewalker]

Re: 110 johnson won't start after overheating

I'd start with a compression test. Good chance the motor has internal damage if it got hot enough to melt stuff...

 

[cosworthrs500]

Re: 110 johnson won't start after overheating

Does the engine turn over, have you checked spark and compression?

engine turns over... I have not yet checked spark/ compression as I didn't have my tool box with me.

 

[cosworthrs500]

Re: 110 johnson won't start after overheating

also I did a decarb earlier in the week, gallon of premix with some seafoam. not sure if this would have anything to do with it.

 

[Silvertip]

Re: 110 johnson won't start after overheating

also I did a decarb earlier in the week, gallon of premix with some seafoam. not sure if this would have anything to do with it.

No it didn't.

 

[cosworthrs500]

Re: 110 johnson won't start after overheating

Spark is good on all cylinders, however compression is not;
starboard top 30psi portside top 50psi
starboard bottom 50psi portside bottom 70psi
Going to pull the heads tomorrow and hope to see some gasket carnage

 

[boobie]

Re: 110 johnson won't start after overheating

Didn't you get an over heat horn ??

 

[cosworthrs500]

Re: 110 johnson won't start after overheating

Didn't you get an over heat horn ??

no overheat horn, but then again I've never heard any beeps ever. not sure if the horn is broken or if it was disconnected by the previous owner.

 

[boobie]

Re: 110 johnson won't start after overheating

When ever you get the mtr fixed be sure to check into the overheat horn.

 

[cosworthrs500]

Re: 110 johnson won't start after overheating

ok, I finally got the heads off. The head gasket on cylinder 1 is definitely blown, so that kind of explains the 30psi reading. The gasket seal rings for the rest of the cylinders look to be in tact. The rubber deflector between cylinder 1 and 3 got so hot that it turned plastic like. The other 3 remained soft and flexible. #1 piston also looks pitted, not sure what this means? How loose should the pistons be in the cylinders? it feels like they all have about 1/16" wiggle room in there. There is no scoring on any cylinder walls.

should I get a set of gaskets, put the heads back on and check if compression changes??

not sure where I go from here?? never been down this road before

 

[Anchor Marine Repair LLC]

Re: 110 johnson won't start after overheating

ok, I finally got the heads off. The head gasket on cylinder 1 is definitely blown, so that kind of explains the 30psi reading. The gasket seal rings for the rest of the cylinders look to be in tact. The rubber deflector between cylinder 1 and 3 got so hot that it turned plastic like. The other 3 remained soft and flexible. #1 piston also looks pitted, not sure what this means? How loose should the pistons be in the cylinders? it feels like they all have about 1/16" wiggle room in there. There is no scoring on any cylinder walls.

should I get a set of gaskets, put the heads back on and check if compression changes??

not sure where I go from here?? never been down this road before

I wouldn't put any money into this motor based on your information. Anything you do will be trumped by the fact you have piston damage. You may not think the cylinder walls are scored, but I can assure you the piston skirts are damaged.

 

[emdsapmgr]

Re: 110 johnson won't start after overheating

Your current compression is way below that which is required for the engine to run. Normal is around 100 lbs. If you've got pits/dents on the piston crown, it's possible that the dented piston has lost the top ring. A common failure mode on this engine. Are there also pits on the face of that side of the head? Move the piston around by hand and use a flashlight to check the top ring. Does it appear intact? If the ring is missing (also a reason for low compression) you'll need to tear the engine down and assess any damage. A scuffed piston indicates poor fuel/lubrication or an overheat, or both. It's normal for the pistons to have the clearance you indicate.

 

[cosworthrs500]

Re: 110 johnson won't start after overheating

thanks for the input everyone. i got a few quotes for a rebuilt poweread and i almost fell out of my seat. ended up checking the local classified and picked up an 87 110hp johnnie for $350 without the gear case. should be back on the lake this weekend.