Seized Mercruiser 4.3L, GM, 1995 in Regal 202SC

[Woody-jh]

Boat ran A1 last Friday. Great day coming up Sunday in massive Great Lakes Heat Wave! Turned ignition key, engine grabbed tight after 1/2 second. Checked prop- nothing around it. Pulled engine cover-nothing strange there. Tried key again- engine grabbed tight again. Now worried-tried checking oil- no bad signs. Tried key one more time- engine grabbed tight again. (End of boating day). Boat taken to marine mechanic. Mechanic suggested pulling starter. Starter teeth worn a bit, but mechanic noticed worn teeth on flywheel. Rebuilt starter, reinstalled and boat started quickly but sounded terrible. Mechanic also noticed gasket leakage around both exhaust plenums upstream of the exhaust check valves. These parts were pulled and replaced last year in order to replace the exhaust check valves. Further dialogue with two marine mechanics. Recommendation is to pull engine, pull exhaust manifolds, check flywheel and check for cylinder damage. If any suspicion of damage, either rebuild the engine or purchase crate engine. Mechanics opinion is that I have "classic hydraulic lock," probably caused by a leaking gasket on the exhaust housing on each side of the plenum section upstream of the exhaust check valves. Mechanics opinion is that the starter has enough torque to damage the flywheel and possibly bend a connecting rod. Repair estimate- two weeks to start job, two weeks to rebuild as this is peak season. End of boating season, (and maybe boating career). Not happy that something so serious could happen to someone who looks after the little things, and to a motor that only has probably 250 hours in 10 years. Suggestions? Rebuild? New crate engine.

 

[TilliamWe]

Re: Seized Mercruiser 4.3L, GM, 1995 in Regal 202SC

suggest: find mechanic that knows how to check things while engine is in the boat

 

[TilliamWe]

Re: Seized Mercruiser 4.3L, GM, 1995 in Regal 202SC

remove spark plugs, blow water out of cylinders & spray oil in there to protect the bores<br />then check manifolds. they could have bad gaskets or they could be junk. Who did the work on it last year... cause they messed up if it's a gasket problem.<br />In all, lots o'work to be done before pulling engine. Your shop is greedy.<br /><br />As usual Dn S explains in very good detail the process you should follow below. Notice it doesn't include "pull motor"?!

 

[Don S]

Re: Seized Mercruiser 4.3L, GM, 1995 in Regal 202SC

From what I understand, engines with fresh water in the cylinders don't go bad and lock up after 12 hours.<br />Pull the sparkplugs and crank the engine over and see if there is water in them.<br />If there is, block off the hose coming from the drive that supplies water. Start the engine after you dry out the cylinders and plugs a bit and start it up for 10 or 15 seconds.<br />Wait for things to cool down. (should only take one beer) then do it again for 10 or 15 seconds.<br />this may have to be repeated a few times till the water is burned out of the cylinders. Since none is allowed back in, you save your engine.<br />Spray some fogging oil in the carb on the last run to help coat the cylinders, and figure out how you are going to cure the problems permanitly.

 

[Woody-jh]

Re: Seized Mercruiser 4.3L, GM, 1995 in Regal 202SC

Shop that replaced exhaust shutters last year is out of business, but was reputable. I'm limited with marine engine experience, therefore trusting the shop's judgement. Second mechanic is a friend, long time boat owner. Engine access to do any repairs in place is very poor. First repair attempt (rebuild starter) was to try and get me back in the water this year, with expectation that winter time repairs (flywheel) would be needed. Current prognosis: bleak

 

[TilliamWe]

Re: Seized Mercruiser 4.3L, GM, 1995 in Regal 202SC

for you, yes it is bleak.<br /><br />Good luck

 

[Woody-jh]

Re: Seized Mercruiser 4.3L, GM, 1995 in Regal 202SC

Any opinions as to whether the starter is powerful enough to damage the flywheel (teeth, or break welds on the ring gear to flywheel)? Could it even damage a rod? Again, I'm an engine novice, but would have thought that something would have let go (shear pin would be nice) before the whole engine wrecks itself.

 

[Don S]

Re: Seized Mercruiser 4.3L, GM, 1995 in Regal 202SC

If you don't get a starter on there and get the water out of it and the engine started, you WILL be looking for a new engine soon.

 

[Woody-jh]

Re: Seized Mercruiser 4.3L, GM, 1995 in Regal 202SC

Don, The starter was rebuilt and the engine restarted. Shop said it sounded terrible though and they are very concerned about flywheel damage and more... (Possibly broken welds on ring gear to hub,bent connecting rod, etc) <br />Shop tells me that this is the third similar repair this year- the other two were on V8's. If I understand it correctly, I have the equivalent of an exhaust manifold gasket leak, with the water leaking from the cooling jacket back into a cylinder, through an open exhaust valve. It could have happened when the engine was shut down after the last use. So if a new engine is needed, is a rebuild the way to go, or are factory replacements any cheaper (and faster to get me back into the water) P.S. I am on a budget, love my boat, but not one of those boating types that would sell their first born to fix their boat!!

 

[Don S]

Re: Seized Mercruiser 4.3L, GM, 1995 in Regal 202SC

Glad it was started, now you know water sitting in the engine isn't going to be the problem.<br />The only thing to do now is pull the engine, look at the ring gear (they are not welded on) and replace it if bad. Do a compression test if possible, then pull the heads and physically look at the cylinders and valves. If a bent rod the piston would not come to the top of the cylinder like the rest do, and the valve indents probably won't be straight across like the other pistons. The valves can also be checked.<br />No need to buy an engine if it's not necessary.