03 150 Johnson locked up

[james williams]

I would like the experts opinion on this.It locked up just after it planned off.He filled up the tank at a different place.87oct.ngk plugs,not Johnson oil,5000 rpm very maximum[set up this way by the dealer]It did`nt smoke at all that day,no bells went off,water coming out of tell-tale hole,water pressure gauge good.Mech,put fuel pump on a few days before[why,I don`t know]He went back to the mech.he said the OIS caused the problem.I took one head off,the cylinders have a few small scratches,but not bad.I don`t know how the pistons are.I don`t see any scuffing on the cyl.walls.The mechanic is not the dealer.There is plenty of oil in the cyl.Before I work on it,I would like to know what caused this.I think it was the gasl or the low rpm or both

 

[tashasdaddy]

Re: 03 150 Johnson locked up

drop the lower unit. it may have locked up, and that will keep the drive and crankshaft from turning.

 

[jonesg]

Re: 03 150 Johnson locked up

I would wonder about a tech installing NGK plugs, theres been plenty of melted pistons noted here on iboats due to those plugs.

Anyway, next step is as tash noted, drop the lower unit to find which end is locked.

 

[james williams]

Re: 03 150 Johnson locked up

Thanks,tash and Jones.I really had`nt thought of that!!!!! It`s not at my shop yet,I`ll bring it home Monday.I went over to his home this evening and drained some oil out of the foot.It was perfect.I think it still could have been the problem.The cylinders are barely scratched.The tech said #2 and #4 were dead.I do`nt see that much damage.I`ll check deeper monday.Thanks..james

 

[james williams]

Re: 03 150 Johnson locked up

I got this boat [my nephew`s ] to my place yesterday.I got it tore down.#4 piston is scuffed solid,cyl. totally lined with aluminum,but not to deep.#6 piston had chunks tore out ,eat up.Cyl.not bad at all.#2 pis.small scuff.Cyl. no damage.I`ve got all cylinders honed like new [one hour ].The motor had one-hundred hours.The question I don`t have an answer to is WHY, what caused it??? I checked all the intake gaskets,nothing visable.I could`nt find any cracks in the manifold [plastic]. If it was [can`t believe it was ] the oms ,why two cyl.??The three on the strbd.side are like new.Do I need to find the cause before I do anything else ?It appears like something went wrong in the bottom of the port side. Maybe a small monkey got in there?? There is a lot of talk going around here that a lot are breaking down with close to one-hundred hours.Some are saying the alcohol gas is at fault????
Thanks

 

[jonesg]

Re: 03 150 Johnson locked up

The biggest cause of piston/cyl failure is clogged carbs, take em apart and inspect the jets , they might be dirty. It only take a bit of dirt.

And NGK plugs can cause problems themselves.

 

[spucky]

Re: 03 150 Johnson locked up

This tiny sliver of hose was stuck in the inlet seat of a 1988 looper, the carb was spotless, this was found in the float valve seat after removing it and was limiting flow. Must have peeled off the inside of a hose between the filter and carb. Did this to a rebuilt powerhead, the other three cylinders were fine, probably what killed the first engine.

 

[Dhadley]

Re: 03 150 Johnson locked up

That motor is particularily sensitive to spark plug heat range. The NGK's certainly could contribute to the issue. The low rpm (lugging) set up doesn't help. Lugging and incorrect plugs can spell disaster for that model. If there was oil in any cylinder the pump was not at fault, it cannot pick on one or two cylinders and not the rest.

If you honed it for an hour it'll need boring now. Probably did anyway.

 

[james williams]

Re: 03 150 Johnson locked up

Jones,, I think you hit the nail on the head.
Spunky,,I will take care of what you said tomorrow.

QUOTE-``That motor is particularily sensitive to spark plug heat range. The NGK's certainly could contribute to the issue. The low rpm (lugging) set up doesn't help. Lugging and incorrect plugs can spell disaster for that model. If there was oil in any cylinder the pump was not at fault, it cannot pick on one or two cylinders and not the rest.

If you honed it for an hour it'll need boring now. Probably did anyway.``

What I meant was,I spent an hour honing all six,mostly the two worst..I agree 100% what you said about the NGK,the low rpm and the OMS.I tryed to get him to let me turn the rpm`s up,but he would`nt let me.Easy,it sets a mile too deep. Thanks all,,,james

 

[Dhadley]

Re: 03 150 Johnson locked up

It's gonna need boring, I'd bet on it. Besides, the piston is the most expensive part. If you're buying new pistons, you might as well bore it to have all the life in a rebuild.

 

[james williams]

Re: 03 150 Johnson locked up

Thanks ,Dale.I`ll put that on my to-do list Monday [ he`s paying the bill ]Yeah,there`s no need to cheap-scape on a motor that new.,, Thanks,, james

 

[Faztbullet]

Re: 03 150 Johnson locked up

Been following post and have to say I have never had a NGK plug burn up a engine, and I have been doing this since 78. All my rebuilds and tune ups(outboards and sterndrives) get NGK plugs. The only motors I run Champions in is the Fichts and Forces. I guess if you have the improper plug and heat range it can /will happen. I would like to know what the NGK # was in this engine, it should have been BPZ8HS-10

 

[james williams]

Re: 03 150 Johnson locked up

The plugs are as you stated--------BPZ8HS-10-----With NGK-R on the opposite side ,Thanks,,,james

 

[Dhadley]

Re: 03 150 Johnson locked up

I've seen it many times. Seen a commercial guide with that same style motor who ran it 6-7 days a week for several years, never an issue. Put NGKs in and made it about 3/4 mile. Ran it several more years once the powerhead was rebuilt, always Champions, never an issue.

Maybe if the motor wasn't being lugged you could slide by. With a non-recommended plug and the lugging combined the chances are pretty good that something bad will happen eventually.

 

[james williams]

Re: 03 150 Johnson locked up

Something I had`nt though of before,just remembered.When he fires it up,he`s gone,wide open.No warm-up at all.I`ve read a lot where the piston and cylinder need to reach the same temperature.I always play around with my motor and let it warm-up.

 

[james williams]

Re: 03 150 Johnson locked up

I took all three carbs. on port side completely apart.Nothing was in them.I could`nt find anything in the throttle-body.I can`t find anything wrong with gaskets.Where the block bolts together,there was just a sealer of some sort,that`s about the only thing I can think it might be. james

 

[james williams]

Re: 03 150 Johnson locked up

Between the wrist-pin and the crown of the piston on the four good cylinders ,There is about a one-sixty-fourth of an inch layer of carbon.On the two bad pistons,there is none,In other words,two bad pistons are like new underneath,inside. Four good pistons, full of carbon underneath,inside.Could that be caused by not enough fuel at two bad ones. [no gas means no oil]??

 

[HybridMX6]

Re: 03 150 Johnson locked up

Depends. How did the head look? Just as clean as the pistons? If the 2 bad cylinders are virtually squeeky clean, you could have had water getting in the cylinder and essentially "steam cleaning" those two cylinders.
I don't have much experience with boat motors yet, but I know from doing some work on imports (cars), running lean will burn off everything in that cylinder, then depending on how bad it is, will melt pistons. No fuel will also mean no lubrication for an outboard. Do you still have the old head gasket? If so, any signs of breakage, or signs of where water could have passed between the water passages and cylinders in that area?

 

[james williams]

Re: 03 150 Johnson locked up

Thanks,The tops of pistons were equal,slightly covered with carbon. The heads were all equal,very little carbon but pretty much right. The head o-rings are good. When I say two pistons were very clean,they are clean inside the pistons,where the wrist-pins are. Thanks

 

[James R]

Re: 03 150 Johnson locked up

Just now rebuilding a 93 150 Johnson. The port cylinders were all scored. The starboard were like new with the cross hatching. The only thing I discovered was that the port side carb flange gaskets were leaking. This could give rise to weak mixture and lub.