Locked up / Seized 5.7 Mercruiser

[parabellum]

Engine: 1995 / Merc 5.7 / Ser # OF267660 / Maxum 2300

Motor has always been slow to start but extra tough to start at end of last season. Parked for winter with heater in engine area, block drained completely, did not freeze.

Tried to start it this weekend, nothing moves except starter which clunks one time.

Installed new starter which was needed, no change.

Pulled plugs, no water came out, right side of engine clean plugs, left side rusted / corroded, more on back 2.

Pulled riser / corroded inside. Blue gasket appears to have leaked. Corrosion inside.

What I know: Manifold to riser gasket leaked, boats been sitting with salt water in engine for 5 months and is now siezed. Block etc. was drained immediately after engine hydrolocked (didn't realize it had happened) and has sat dry for winter.

What I need to know: What do I do now? Can I soak it with Mystery Oil or do I go head shopping? Should I pull the head and look further into the engine?

Lots of guys post about this but their engines turn over, mine does not.

Thanks for any feedback.

 

[Bondo]

Re: Locked up / Seized 5.7 Mercruiser

Ayuh,... After 5 months of saltwater in the cylinders,...
My guess is, you need a new motor...

 

[LippCJ7]

Re: Locked up / Seized 5.7 Mercruiser

If your certain the motor hydrolocked then its a good possibility that you have bent a connecting rod in a cylinder or more, then the possibility of salt water in the cylinders for 5 months.....yeah I think Bond-o is dead on. Pull it and tear into it, if its really a 95 motor then its probably a great time to up power anyway

 

[rickryder]

Re: Locked up / Seized 5.7 Mercruiser

Time for a tear down to see what is needed. It may be rebuildable but ya don't know untill it's torn down and everything checked out....

 

[Don S]

Re: Locked up / Seized 5.7 Mercruiser

Cold hard facts of life.

5 months + salt water in cylinder = Junk engine

 

[300sflyer]

Re: Locked up / Seized 5.7 Mercruiser

As others have stated, your engine very likely needs rebuilding, but you might want to give this a shot. You have nothing to loose but your time by trying.

Mix up a 50/50 mixture of transmission fluid and acetone, and spray it in all the cylinders, and let it sit for a few days. Then try bumping the crank with a breaker bar. If you get it to move at all, rock it back and forth a few times, and then add more oil mixture. Repeat the same process multiple times. You may just get it free enough to turn over with the starter. If so, then do a compression test. If it checks out, change the oil, install new exhaust manifolds, risers, and spark plugs, and you might just be ok.

Keep us posted!

 

[seaboo]

Re: Locked up / Seized 5.7 Mercruiser

+1

As others have stated, your engine very likely needs rebuilding, but you might want to give this a shot. You have nothing to loose but your time by trying.

Mix up a 50/50 mixture of transmission fluid and acetone, and spray it in all the cylinders, and let it sit for a few days. Then try bumping the crank with a breaker bar. If you get it to move at all, rock it back and forth a few times, and then add more oil mixture. Repeat the same process multiple times. You may just get it free enough to turn over with the starter. If so, then do a compression test. If it checks out, change the oil, install new exhaust manifolds, risers, and spark plugs, and you might just be ok.

Keep us posted!

I would try to free the engine first (but yes, cold hard fact, even if it frees up, it may run and be "serviceable" but it will not be right). For reliability and power, odds are a new engine is due.

 

[knotperfect]

Re: Locked up / Seized 5.7 Mercruiser

I feel that you were standing in my shoes about a month ago. Starter clunk, rusted stbd side, and hopes for a Marvel Mystery Oil miracle. The difference was that mine was the original 34 year old Mercruiser 305. Bond-O and others gave me two pieces of advice. 1-start saving for a longblock, 2-Marvel Mystery Oil and a BFH to try to get it to turn.
I went ahead and pulled the top end of the motor and eventually removed and tore it down. #6 was so seized that I needed a 3-lb sledge to pound out the piston from the block. The motor was shot from just the one bad cylinder and I have a new engine being machined now. I am learning that there are a lot of ways to re-power and the advice on the forum, although varied from several differing perspectives, is awesome for keeping you motivated and inspired to learn more about our boats.

 

[parabellum]

Re: Locked up / Seized 5.7 Mercruiser

Ok its soaking now. I live a block away so I'll go re soak it in the morning after work. How many days do you figure I should wait until I try to turn it? Whats the best way to try to bump / turn the engine?

 

[Bondo]

Re: Locked up / Seized 5.7 Mercruiser

Ok its soaking now. I live a block away so I'll go re soak it in the morning after work. How many days do you figure I should wait until I try to turn it? Whats the best way to try to bump / turn the engine?

Ayuh,...

I went ahead and pulled the top end of the motor and eventually removed and tore it down. #6 was so seized that I needed a 3-lb sledge to pound out the piston from the block. The motor was shot from just the one bad cylinder

 

[300sflyer]

Re: Locked up / Seized 5.7 Mercruiser

Ok its soaking now. I live a block away so I'll go re soak it in the morning after work. How many days do you figure I should wait until I try to turn it? Whats the best way to try to bump / turn the engine?

Give it a day or two soaking in, and don't be stingy with the oil. Remove all of the belts so you are not trying to turn anything else. Remove all of the spark plugs if you have not already done so.

You could try with a socket on the balancer bolt, but it will likely just turn the bolt. Failing that, you will need one of these or a homemade equivalent. http://www.summitracing.com/parts/SME-906007/

 

[300sflyer]

Re: Locked up / Seized 5.7 Mercruiser

Any luck getting the crank to move at all?

 

[parabellum]

Re: Locked up / Seized 5.7 Mercruiser

Thanks for asking. I'm going to pick up that attachment for the crank tomorrow and give it a try. Will update then.

 

[300sflyer]

Re: Locked up / Seized 5.7 Mercruiser

Have any luck?

 

[300sflyer]

Re: Locked up / Seized 5.7 Mercruiser

So what was the outcome?

 

[parabellum]

Re: Locked up / Seized 5.7 Mercruiser

FINALLY an update. It wasn't that I was ignoring things, it was that my mechanic turned out to be rather ungrateful for all the work I've given him and took his jolly time fixing my boat. Welded a bolt onto a plate that bolted in turn onto the end of the crank and after a week of soaking the motor, he was able to move it. Rebuilt the heads and cleaned everything out and its practically good as new. Gave me a chance to replace a lot of stuff as well including the leaky risers. Thank you for all your help. Had I taken the boat to a more reputable place I would have had it back for the summer but it was your ideas to try and spin it that ended up working.