Did the marina wreck my engine?

[Olde Chief]

Who is responsible for your engine problems, it is hard to say. It would be hard to prove, if a marina or yard did something to it. This why I only have the engine dealer do my engine work. Must admit that it does sound strange though, it could have been something you did as well. The last time II did have an engine problem, was when I had a yard replace a thru hull and the boat yard used the wrong material to seal the thru hull in place, and it dissolved after 3 days and almost sank my boat. It did cost the boat yard, $25,000 to replace the engine and repair the water damage. fortuneately I had proof that it was the yards fault, with witnesses and pictures. Hope you had proof that it was the marinas fault. Good Luck.

[Bill Seal]

If they had really pulled the engine to replace the pan and flywheel, you know what the R&R cost would be. If they just pulled the trans, it sounds like they're "pulling the wool".
A loose flywheel or broken flex plate sounds like a blown bottom end, my wife's Cherokee was diagnosed as shot mains, but the oil pressure was good, so I took it to a trans shop, found loose bolts on the torque converter. Get a real mechanic to check it out.

[Cadence]

Originally Posted by Joe from ny

Greetings all - I just recently started up my 1995 Larson with twin 5.0 Mercruisers for the first time this season. After about 5 minutes away from the dock, which followed a 10 minute warm up period at the dock, i notice the starboard RPM gauge needle drop a bit, and I heard a loud knocking in the starboard engine. I shut down, and checked around for leaks, checked oil level, etc..., all seemed fine. I started back up and heard the loud engine knock again, like a piston slapping. I shut it down and I finished on to my destination on the port engine alone, although it was a pain to steer due to the power steering pump being on the shut down engine.

When my yard looks at it they say the main bearing, or lower bearing is shot and the piston rod is hitting the cylinder. It needs to be replaced with a rebuilt motor, for a total cost of about $7,000.
Last season they removed the starboard engine to put a new flywheel and new starter, and removed and replaced the oil pan due to rusting issues. I used it for three months after that job with no problem.

My question is - could anything that they did during that job last year cause the bearing to go? Or could anything they did wrong during winterization have caused it? They have screwed up so many minor jobs on my boat in the last two seasons, causing multiple comebacks to correct, including improperly winterizing some waste hoses and a transom shower wand that then needed replacing.

Also, does that price for an engine replacement on this boat seem about right for the New York ?

In addition, could I run it like that with he loud knock till it dies, since I am replacing it anyway, or could there be a catastrophic failure that might be dangerous to the boat out on the water.

Thanks for your advice.


Sent from my iPad using Cruisers Sailing Forum

Doubt it is anything the yard did. Even if it was you would have little or no recourse if it ran three mouths after the flywheel and starter job.

I'm afraid you are just suffering from gas auto block marineization.

[Cheechako]

Originally Posted by guyfromiowa

To answer the question, "How could a piston be hitting anything?" It's like this,normally the piston will be flush with the top of the block at top dead center position. The head gasket is likely compressed to about fifty one-thousandths of an inch. When the connecting rod bearing is loose the piston gets 'tossed' up the bore by the crankshaft, but instead of the connecting rod pulling it back down the bore the piston hits the inside of the cylinder head. At just the right engine speed and load you can clearly hear the noises at the bottom end ans well as the noises from the top end using a stethoscope. With an engine this old you will find a lot of worn parts inside that might have nothing to do with this failure. No cheap fix for this one.

They said the Rod is hitting didn't they?. I too don't think that makes sense unless the piston disappeared!

[hellosailor]

I'm with Bill and Cheechako on this one. Can't see how a rod is hitting the cylinder unless it broke free under the piston head and is slapping around...and I don't see how a bad main bearing would cause THAT kind of a break. Could just be the usual confusion but definitely worth at least a second opinion.


And of course, until someone drops the pan and take a look inside, nothing is for sure.


IF you keep running it, whatever is making that noise will be damaged more severely, and there's always a potential for an engine to literally come apart, or catch fire, so not using it is the only real way to go.


Considering the time of year...it might be possible to salvage the engine and have it rebuilt--rather than replacing it. Either way, the warranty you can get is important.


I know someone who had his (sailboat diesel) engine rebuilt. Told the shop to re-use the bolts on the connecting rods, they were perfectly good and Volvo wanted too much for new ones. Volvo said, no , really, use once and replace. One year later...the re-used bolt had come apart, the engine had to get rebuilt again. So, be wary of any cut corners as well.


I wouldn't think a flywheel replacement could cause a connecting rod or main bearing failure. Of course if someone dropped an extra screw or nut into the crankcase...never say never, but if there was a direct cause I suspect it would have happened much faster.

[lqh442]

a loose flywheel will cause similar sounds I would have that checked first and see if in fact it is an internal problem .

[sailersteve]

No do not run that motor ! It may be able to be rebuilt for less money than buying new replacement.
I see that even you think the marina is incompetent , and maybe they are.
I know of a case where , when changing the oil pan to much gasket sealer was used . At the end of the summer that extra gasket sealer ended up clogging the oil intake tube and seized the motor . The engine mechanic's fault .
If the marina does the replacement , you will never know if anything was there fault .
And why would you take your boat back to a mechanic you don't 100% trust their work.
Take pictures lots of pictures , be there when the old motor is taking apart .

[Ripper10]

Since they removed the pan, and they most likely added oil.

They may have put to much oil in the engine and that would cause the engine to make that type of noise.

Chevy engines are relatively cheap to rebuild.

[44'cruisingcat]

Originally Posted by Bill Seal

Main bearing or big end bearing?
How can a rod hit the cylinder unless the piston has disintegrated?

If the big end bearing temporarily seized and the rod was bent.

[Compass790]

If you are mechanically minded I would check the oil pressure & the compression. DONT keep running the engine if it has a loud knocking as your problems will only increase. ( trust me I found this out) Of course it's possible that the boatyard is responsible for your problems but would be hard to prove unless you are lucky. Doesn't fill you with confidence by the sound of your previous dealings with the boatyard. Agree with the other posts a second opinion may be worthwhile

[shakey doug]

Lever crankshaft pulley to check that end float is not excessive.

[shakey doug]

Forgot to ask in last post, have you pulled Starter to check if complete Pinion assembly is place? Have checked to eliminate a loose drive plate?

[Joe from ny]

Since they messed up some things previously by not winterizing properly, could that have caused the symptom also?

[jimbunyard]

If you don't really know what's wrong, guessing about who caused the problem is an exercise in frustration.


It is odd that the engine ran for three months, apparently without a problem, and then after recommisioning only lasted for 15 minutes.


That doesn't mean that winterization faults are or are not the cause.


Assuming that you have outdrives and not straight inboards, and not knowing the competence of the mechanics you are using, the 'knocking' could indeed be a main or rod bearing. It could also be a severely worn ujoint caused for bad engine alignment when the engine was reinstalled, or a a ujoint worn out by water intrusion from a poor outdrive installation, or a loose or worn engine coupler or even a loose flywheel.


At any rate the engine has to come out to find out what the real problem is, and given the performance of the mechanics you've been using, it makes sense to find some that are more competent, or at least have someone there who is competent when the engine comes out and is torn down.


Regarding the 7000.00 cost if the engine needs to be replaced. You can buy a long block Mercruiser 305 online anywhere for 1500.00 - 2000.00. To remove, replace, realign and reinstall the engine and outdrive should take no more than 6 hours, 3 is a good average time (especially for one that has been recently removed). Add a few hours to change your ancillary engine components to the long block, and a couple more for unforeseen problems and you have, say 12 hours for the swap. (This is not idle speculation, I just completed a 350 removal, rebuild and reinstall last week)


So 12 hours x 100 per hour = 1200.00 labor + 2500.00 for the long block = 3700.00.

7000.00 seems a little steep to me, especially if the mechanics you're using now caused the problem....

[Joe from ny]

Another curious thing i noticed is that the riser exhaust steel band clamp is split and laying in the bilge next to the motor. It is one from the pair closest to the motor. could there have been seawater in there due to a improper winterization which froze and let water get into the cylinder somehow causing hydrolock? The attached photo below is from the internet, and not my actual motor, but it illustrates which clamp (except that it is the other side of the motor).