Sevicing an un-siezed engine

jimrockireland · Jul 9, 2013

I bought a boat with a seized engine. Previous owner ran boat engine out of water, Assuming I can un-seize the engine what other things should I service and/or inspect, replace on the engine and sterndrive? I plan on doing the normal tune-up stuff plus a compression test. This is a 5L mercruiser MCM 228 inboard built in 1983.

Bondo · Jul 9, 2013

Re: Sevicing an un-siezed engine

jimrockireland said:
I bought a boat with a seized engine. Previous owner ran boat engine out of water, Assuming I can un-seize the engine what other things should I service and/or inspect, replace on the engine and sterndrive? I plan on doing the normal tune-up stuff plus a compression test. This is a 5L mercruiser MCM 228 inboard built in 1983.

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Probably the flappers, 'n most likely the lower shift cable got melted,...
The Impeller is No doubt trashed, 'n it's housin' to probably,...

Head on up to the Adults Only section at the top of this forum,...
Lots, 'n lotsa Great learnin' in there,...

Don S · Jul 9, 2013

Re: Sevicing an un-siezed engine

The fact that it was overheated and seized means the engine is junk. 5.7 marine Long blocks are what you want to be looking for.

RogersJetboat454 · Jul 9, 2013

Re: Sevicing an un-siezed engine

Welcome to Iboats.

How long was the engine run with out water?
You may want to start by pulling the drive off to see if it's the engine that's seized, and not the drive that's locked up.

jimrockireland · Jul 10, 2013

Re: Sevicing an un-siezed engine

RogersJetboat454 said:
Welcome to Iboats.

How long was the engine run with out water?
You may want to start by pulling the drive off to see if it's the engine that's seized, and not the drive that's locked up.

The only info I got was it was run out of the water by the son of the previous owner. He was not sure if the pistons seized or the bearings. I will pull off the stern drive and see if it makes a difference. Thanks.

ricohman · Jul 10, 2013

Re: Sevicing an un-siezed engine

What's the difference if its the bearings or rings? Maybe if it was stuck by rust you would have a chance, maybe.

RogersJetboat454 · Jul 10, 2013

Re: Sevicing an un-siezed engine

I agree with the others in that if you find the engine is seized, it's curtains for that engine.

Engines don't heal them selves after severe abuse. If the engine is stuck, and you were able to free it, you're on borrowed time. Borrowed time may be fine for a car engine, as you can always get out of the car and hoof it if need be. Completely different if your motoring along on the drink, and the engine happens to throw a rod. You're then at the mercy of the waves, wind, and tide (if your on the ocean).

Hope that the previous owners story isn't fully factual (as allot of them aren't), and something is up with the drive. Even if it turns out to be true, and the engine is a core, you had to pull the drive to replace it anyway...

jimrockireland · Jul 10, 2013

Re: Sevicing an un-siezed engine

Thanks for the input. It sounds like most of you are saying if it un-seizes, the compression is good and the engine seems to run well it should still be re-built.

Alumarine · Jul 10, 2013

Re: Sevicing an un-siezed engine

I don't think anyone is saying that.

QC · Jul 10, 2013

Re: Sevicing an un-siezed engine

jimrockireland said:
Thanks for the input. It sounds like most of you are saying if it un-seizes, the compression is good and the engine seems to run well it should still be re-built.

Actually what I think they are saying is that if it seized due to an overheat (run without water) then it's not going to get better no matter what you do. If pistons have stuck due to an overheat, then the cylinder walls are toast. And overheat should not cause a bearing failure, but that's also never going to fix itself. If it was "stuck" due to sitting around (rust), then maybe, but not due to an actual failure (overheat leads to bad things, stuff breaks, engine seizes.)

RogersJetboat454 · Jul 10, 2013

Re: Sevicing an un-siezed engine

jimrockireland said:
Thanks for the input. It sounds like most of you are saying if it un-seizes, the compression is good and the engine seems to run well it should still be re-built.

It may be able to be rebuilt (with a professional machine shop involved) if the damage isn't too severe. But as Don alluded to, replacing it with a 350/5.7L long block would cost about the same, and give you some extra power.

jimrockireland · Jul 11, 2013

Re: Sevicing an un-siezed engine

If the engine is toast (not even rebuildable) my back-up plan was to get a short block and re-use all the parts off the old engine. If I went to a 350/5.7L long block would it be compatible with the stern drive? would it mount the same way in the boat? and could I re-use the parts from the 305/5L engine?

RogersJetboat454 · Jul 11, 2013

Re: Sevicing an un-siezed engine

jimrockireland said:
If I went to a 350/5.7L long block would it be compatible with the stern drive? would it mount the same way in the boat? and could I re-use the parts from the 305/5L engine?

Yes, Yes, and Yes.
The exterior of almost all small block Chevys are the same. All you would need to do is find a 5.7L from the same era (2 piece rear main seal, old style pre '87 heads) if you wanted to re-use ALL the parts.

You could go with a newer style engine, but you would have to get a 1 piece rear main seal flywheel, a new coupler, the correct intake ('87-95 or '96+ for Vortec), and may need to add a electric fuel pump if the block doesn't have a provision for a mechanical pump.

Sevicing an un-siezed engine

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