Locked Up Motor

jeffk

jeffk

New Member
Apr 28, 2009
273
Sarasota, Florida
Boat Info
2006 300 Sundancer
Engines
5.0L Mercruiser w/Bravo III
Coming back from a 3 day weekend trip, Docked, cleaned the boat, started each motor to run flush through them. Starboard motor failed to turn. Fried the starter in the process. Next day, found a little water in the plug holes, but may have been from not draining all the water from the manifold when I pulled it. Pulled the boat yesterday, drive is fine. Found a small crack in the elbow. Being only a week, do I try to salvage the existing motor, or get a new long block?
 
The boat ran fine while you were out? Seawater or freshwater cooling? What did you run flush through, and what was it? You mentioned pulling the manifold - you mean the exhaust manifold? Small crack in what elbow - the exhaust manifold?
 
Well, based on you're in Sarasota, and the exhaust manifold developed a leak after 4 years, Im going with salt water. Is the engine turning over now?
 
Seawater cooled, No, I wasn't able to start the motor to flush it, I use the Neutra Salt flush kit. Nope, still not turning over, I am going to ask the mechanic to pull the heads first to check the damage, rather then just pull the motor. He wants to install a long block, rather than spend time rebuilding the motor, which I understand. Labor vs new longblock. How much damage can salt water do in a week in a cylinder? There isn't any water in the oil.........yet!!

If necessary, where can I pickup a 5.0l longblock? From what I've seen so far, they are about $2500?
 
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Pull the plugs and see if it turns over. If so I would do a compression test on it before I would pull the engine.
 
Who has the best deal on parts? Longblock, risers, the kind of things that need replacing while the motor is out?
 
It's worth it to spend a hundred bucks or so to pull the head and inspect it and the pistons. Why does the mechanic not want to check it out first. If I'm installing a new long block I sure would like to know what took the old engine out. But that's me.
 
Yep, the motor is out, he is removing the heads tomorrow. Just want to get ahead of the parts. I will be out of town for a week.
 
Looks like we are rebuilding the existing motor. Out of the water 2+ weeks. :huh::smt009
 
Hey Jeff,
Looks like we are both in the same boat. Almost the same thing has happened to me. See my post "Is it time for a valve job"
Good luck, I'm not sure what to do either.
 
To me it sounds like your mechanic wants to go the easy way out. This is BS by alot of mechanics. All he wants to do is just replace the engine and drain your wallet. Not the correct way to go about it if you ask me. I would of removed plugs and run a comp test and pressure the water system to see if water pours out of a plug hole. The engine I am doing now had good compression (150 psi) but when we pressured the water system #1 cyl was flowing water out the plug hole. Some people just dont want to spend a few min to find the issue and fix it. Instead "Lets replace the engine" is what he tells you. BS
 
The engine is locked up anyway, so it needed to come out. We are looking for the cause too, which is still a mystery as to where the water came from to begin with.
 
Hi Jeff, I've heard of "unexplained" water intrusion a few times and there are two possible causes that I know of.
1) one guy was on full step and accidentaly pulled the safety off killing the motor. As it was still in gear, the momentum kept turning the drive and water was pushed in through the exhaust. Sort of like "braking" a car with a stick shift transmission.
2) another guy was flushing/running his motor while on the trailer but didn't remove the straps that held it down. He backed down the ramp (in fresh water) fired up for a minute then shut it off. The exhuast was below the waterline enough that water made its way through the exhaust again. He didn't know it then but next time he tried firing, the motor was full of water.

Don't know if either could be your issue but thought I would throw it out there.
Good luck!
 
Sounds like salt water injestion through the exhaust manifolds. I had the heads pulled, polished at the machine shop and replaced all 4 manifolds. Exactly the same thing happened to me 3 weeks ago. Running perfectly after the repairs. My 340DA had aluminum exhaust manifolds. Your may be the same. Get the cast iron replacements. What is a "Neutra Salt Kit"?
 
I had an engine that was working. I stalled it out and couldn't get it started again. Cranks but doesn't start. We did get it to start briefly, but would stay running. Anyway, my mechanic supects that water has started to leak into the engine from the Manifold. This may be causing rust in the engine preventing it from firing up. He is going to remove the manifold and inspect the engine next week and see what we have to deal with. In the mean time he drained the manifolds and put oil directly in the engine to prevent an further rust if that's what's going on. I'll let everyone know what we find just in case it helps. He says this is a fairly common problem with older engines like mine.
 
jeffk said:
The engine is locked up anyway, so it needed to come out. We are looking for the cause too, which is still a mystery as to where the water came from to begin with.
Click to expand...

You mentioned flushing..
Was the city water hooked up with the motor not running for more than a minute?
That might have backed up into the exhaust and flooded your engine.
That could be where the water came from.
 
They are still working on it. Hopefully I will have an update by the end of the day.
 
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