Frozen motor/rebuild questions

[silveraire]

I recently purchased a boat that had a 1985 50hp johnson vro that was ran with no oil and froze. My question here is, when a motor locks up, what damage is done to the block? does it warp, and can it be reused. Can I just get it bored and decked and go from there? I understand that situations vary, but the best advice would be appreciated. The rest of the unit is fine. Maybe just better to part it out.

 

[KYHunter2]

Re: Frozen motor/rebuild questions

There is no standard , as far as damage, from a no lubrication failure, is concerned.

Its very possible a rebore , will be all thats needed , prior to rebuild.

You'll need to have a machineist , or someone that knows how, go over the block / crankcase / heads .

To see if it is boreable / useable.

The old motors are tough critters, and its very likely, useable.

As long as it hasn't been bored, too many times in the past.

And , theres no damage to the crankcase.

Good - Luck,

KYHunter

 

[emdsapmgr]

Re: Frozen motor/rebuild questions

If the engine locks up from overheat, usually the piston will cool down, and will eventually again move in the cylinder. While serious, this failure may not be catastrophic. If, during the overheat, a ring lets go, part of the piston breaks away and lodges under the head, or the piston delaminates onto the cylinder wall, it may lock in place. This is more of a problem. You are correct, usually an overbore with new pistons will take care of the problem. Pull the heads off and see what it looks like. Esp check the intake and exhaust port bridges to be sure they are intact and not cracked.

 

[clint]

Frozen motor/rebuild questions

Just do a rebuilt powerhead. Best to scrap the old clunker. You don't know what other damage could of occured with the crank and rods. Extreme heat causes lots of unoticed damage that will haunt you later.
CLint :$

 

[Solittle]

Re: Frozen motor/rebuild questions

Before you part it out or commit to a rebuild take the plugs out, tilt it up and put a few tablespoons of Marvel Mystery oil in it and let it sit for a couple of days. Then take a socket wrench to the flywheel nut & see if you can turn it.

Let us know if it breaks free. Often they will.

 

[silveraire]

Re: Frozen motor/rebuild questions

aleady have is soaking in oil, it has been sitting for 3 days. going to try to break it loose tomorow. will let you all know what happens

 

[clint]

Frozen motor/rebuild questions

Good Luck!
clint d

 

[kenmyfam]

Re: Frozen motor/rebuild questions

No matter what a powerhead teardown is a must. Thorough inspection for any and all damage and a careful rebuild, otherwise you will have serious issues down the road.

 

[silveraire]

Re: Frozen motor/rebuild questions

after soaking for 4 days, she finally broke loose today thanks to a bunch of oil and elbow grease. Now, time for the rebuild. I think that I am going to try to rebuild this myself, is that crazy? Never had a marine engine open but am quite familiar with auto engines. How hard could it be. 8) I have ordered the seloc and clymer manuals. can anybody tell me where to get a complete rebuild kit? I am entering new teritory here, so any advice would be helpfull. Thanks in advance.

 

[silveraire]

Re: Frozen motor/rebuild questions

just a subnote to the last post, the reason I decided to rebuild myself, local marina charges $75.00/hr for labor. insane

 

[kenmyfam]

Re: Frozen motor/rebuild questions

No reason that you can not do the job yourself. Take your time and follow the manual carefully. Ask as many questions as you need to out here and you will not go wrong. As my old mentor used to say when I was learning my trade, "if man made it then man can fix it" (or woman that is) not wanting to appear sexist.

 

[silveraire]

Re: Frozen motor/rebuild questions

^^^

 

[Solittle]

Re: Frozen motor/rebuild questions

Well before you stat rippin it apart pull the plugs if not already out and do a compression check. Post the results back here. Also what do the plugs look like?

You may also want to pull the head to see if the cylinder walls are scored. If not - - - - - -

If you get lucky you may not have to do a rebuild.

 

[clint]

Frozen motor/rebuild questions

I agree with the Vice Admiral. If you do a thorough compression test and f the results are good, I would not go with a rebuild. After compression test do remove your heads and see if any of the cylinder walls are scored. You might be a Lucky man and get away with rebuilding. Then I would go thru all checks of carbs and clean any burnt oil, or gas residue due from the extreme heat. Good Luck!
Clint 8)

 

[silveraire]

Re: Frozen motor/rebuild questions

compression as followes: 1- 98 lbs, 2-27 lbs

number 2 has broken ring and scored wall in 3 places. number 1 cylinder not bad but rings look to be worn.

 

[silveraire]

Re: Frozen motor/rebuild questions

what should my compression be for this outboard?