siezed '79 Johnson 140hp, advise needed

[oldrudedude]

Yesterday purchased a boat with a siezed '79 Johnson 140hp. Motor will be winter project. The PO couldn't help me much as to the cause of the sieze. First boat for them and first time they had it on the water. I'm guessing they didn't mix oil with the fuel. Mild mannered husband:redface: said he DID mix it and his holy terror wife elects to blame the guy they bought it from for selling them a bad motor. Regardless, it is now my problem.

I am presently assuming no oil and therefore total rebuild, But I am certainly open to more experienced and optimistic solutions.

Is this motor worth a powerhead rebuild or better to part out? What would the sticker shock be for the parts for a (some doofus didn't use oil) powerhead rebuild? Some kinda' ball park figure would do.

I have never rebuilt a two stroke butwould be up for the project if it is worth while.

 

[kenmyfam]

Re: siezed '79 Johnson 140hp, advise needed

You will need to do some basic investigation to assess just what you are up against before you start to spend money on it. Whip the heads and exhaust covers off and take a look inside. If you find a total mess then personally I would part it out and put the money towards a replacement power unit for your boat. If you choose to re-build then the parts and time involved will most likely outweigh the value of the rebuilt motor.
Is the power head burnt and discolored ??
Post some photos if you can for everyone to review.
By the way, where are you in Southern Ontario ?? I could be just down the road from you.

 

[oldrudedude]

Re: siezed '79 Johnson 140hp, advise needed

Thanks for the response kenmyfam. I tend to agree with you on the cost of rebuild. I shy away from rebuilds specifically for that reason. I was hoping there might be a less devastating and final cause of siezure common to this engine. Running without oil and cooling system failure are both pretty final.

I live in Everett. I usually put the boat in at Lake Simcoe or Georgian Bay. We're still waiting for summer here.

 

[kenmyfam]

Re: siezed '79 Johnson 140hp, advise needed

Thanks for the response kenmyfam. I tend to agree with you on the cost of rebuild. I shy away from rebuilds specifically for that reason. I was hoping there might be a less devastating and final cause of siezure common to this engine. Running without oil and cooling system failure are both pretty final.

I live in Everett. I usually put the boat in at Lake Simcoe or Georgian Bay. We're still waiting for summer here.

Still waiting here as well. Was up in Georgian Bay a few weeks ago near Lions Head. Beautiful place, not so beautiful weather !!! (compared to last summer that is) we will be up there again for the labour day weekend. Hope it improves by then.

Good Luck with the motor.

 

[oldrudedude]

Re: siezed '79 Johnson 140hp, advise needed

I took some time to look at the 140hp today. I decided not to tear parts off until I further determined how solidly it is siezed.

I took out the plugs and dumped WD-40 into the cylinders. I was too impatient to let it soak, so I got out my big honkin' screwdriver and began to work the flywheel against the lift bracket. Working it back and forth, within a minute it was moving half a tooth. After five minutes of moving only half a tooth there was a release of sorts and I was able to pry the flywheel tooth by tooth a full revolution of the crankshaft. It is moving but it is very stiff. I am able to turn the flywheel by hand (very stiff) for only about 120 degrees of the rotation. The rest of the rotation I have to pry tooth by tooth with the big honkin' screwdriver.

What should be my next move? Take off the heads and exhaust manifold? Or is there something under the flywheel that could have packed up and caused the siezure?

 

[crb478]

Re: siezed '79 Johnson 140hp, advise needed

Pull the heads and look over the cylinder walls and the tops of the pistons. Then pull the exhause covers off and look to see if the rings are stuck or broken. I would not rotate it too much until you know you are not doing any more damage. You might get luck with this one and there could be a stuck ring or it could just be really carboned up. Once you know the condition inside it will be easier to decide what to do next.

 

[oldrudedude]

Re: siezed '79 Johnson 140hp, advise needed

I pulled the heads off today and found a blown head gasket on lower left cylinder. I am sure I did not break it when I removed the head. The top of the piston and head a a little pitted from something rattling around in the cylinder. Cylinder walls do not appear to be scored, although lower left does have more surface rust marks than the other three.

I am having a little trouble getting the "bubble back" water jacket cover off the exhaust housing. There does not seem to be enough clearance between the exhaust housing and engine shroud to get the cover off. Surely I don't have to remove the power head to get in there?

Any advice.

 

[emdsapmgr]

Re: siezed '79 Johnson 140hp, advise needed

The head pitting is from pieces of the piston ring which let go. Pcs of the broken ring may still be catching on the intake/exhaust ports, making it hard to turn over.The broken ring pieces work their way up into the combustion chamber from the intake ports. They rattle around till they are broken into bits, then they exhaust out the bottom of the engine. You may find small pcs in the exhaust in the lower unit. With a broken ring(s) you are looking at a complete teardown and at least one new piston/ringset. Best to rering the other three, if the pistons are ok. If the cyl walls are bad, you will need to overbore it. You will know more when you get it torn down. Pull the bubble back off when you get the powerhead on the bench.

 

[oldrudedude]

Re: siezed '79 Johnson 140hp, advise needed

Thanks for the response. Do you think the head gasket blew because the rings blew? If the ring set has disintegrated, what is the probability that the piston grooves are also deformed? From what I have seen so far the cylinder sleeves look OK. If I have to replace the piston and four ring sets, plus gaskets, seals and "O" rings is this engine worth saving?

I was having fits trying to get the bubble back off. There just isn't enough room. I'll take the power head off as soon as i can get at it. Is there anything I should know before I start? Shift lever?

 

[kencat]

Re: siezed '79 Johnson 140hp, advise needed

Probably best to drop the lower unit first. If the splines are stuck, best to deal with it pulling the lower unit, not trying to fight with the powerhead. If you have to pry the powerhead sideways a bit to release the gasket you don't want the driveshaft splines engaged. This way the shift lever is out of the way as well.

 

[oldrudedude]

Re: siezed '79 Johnson 140hp, advise needed

Thanks, I'll try that.

 

[ozzgood2001]

Re: siezed '79 Johnson 140hp, advise needed

i got my bubble back off by removing the offending piece on the rear of the cowl. a lil alignment nub was holding me up and having the coils loose lets it slide up and forward the off

 

[oldrudedude]

Re: siezed '79 Johnson 140hp, advise needed

Good point. That alignment tab IS what is preventing me from removing the bubble. Thanks.

 

[ozzgood2001]

Re: siezed '79 Johnson 140hp, advise needed

yep clipped mine off then you still gotta lift just right and it almost falls out then!

 

[emdsapmgr]

Re: siezed '79 Johnson 140hp, advise needed

When a ringset disintegrates it will likely fatally damage the ring grooves. In addition, it pits the piston surface. I would not run a pitted piston, as the pits can cause hot spots when the engine is running. Same with the head that is pitted. Sometimes bits of the ring will enbed in the head, and you have to look hard for these bits. These ring bits can come out (work loose) when running after a rebuild. It is possible that the cylinder walls will be ok. Esp- check the areas around the ports. These critical areas can get damaged when the ring catches in these ports. Make sure none of the port bridges are cracked.

 

[oldrudedude]

Re: siezed '79 Johnson 140hp, advise needed

I clipped the little alignment tab and pulled the bubble back. The view through the exhaust ports told me a lot. The lower port side piston rings appear good through the exhaust port, but the top of the piston moves too freely from side to side so I suspect there is a broken ring on the intake side. The starboard side piston are another story. Serious damage to the piston tops, but the damage looks old because it is all carboned over.

The view through the starboard exhaust ports was even more depressing. Top piston compression ring has a chunk missing.

.

And lower piston compression ring appears to be mostly absent.

This engine has suffered some major abuse. At least 2 and probably 3 ring sets blown. What did they do to it? I suspect more damage inside also. I was able to rotate the lower starboard piston slightly in the cylinder and there was a noticable clunking when I did (wristpin/rod?).

The Cylinders themselves look not bad and the headgaskets look new (no carbon deposits). Looks like someone replaced the headgaskets after the rings blew on the starboard side. Maybe the headgasket blowing on the port side is what finally stopped it.

I wish I knew what happened to this motor. I guess it doesn't matter because it is probably beyond repair. Has anyone seen carnage like this before?

 

[kenmyfam]

Re: siezed '79 Johnson 140hp, advise needed

I am sure it has been seen several times before. Depends how much time, money and effort you want to put into it to make it better as to whether it is worth it or not.

 

[emdsapmgr]

Re: siezed '79 Johnson 140hp, advise needed

I agree with KenM. The damage you are seeing is not unusual for the crossflow family. Even though it looks dire, I would not give up on it yet. Pull the block down and inspect it thoroughly. If a rod went through the side or if the block is cracked in the port area-then it would be scrap. If The block is solid and borable-it is rebuildable. Check out replacement parts pricing and honing or boring costs, then check out pricing on a new engine or a replacement engine. Then decide.

 

[oldrudedude]

Re: siezed '79 Johnson 140hp, advise needed

Thanks all for the advice. I don't think I will go further into it right now. Good winter project. My next move will be to pull The 140hp off the boat and replace it with my 100hp. Hope to get the boat in the water before the summer is totally gone.