Blown engine

[sailor25b]

Boy, do I feel stupid...

I was having intermittant trouble with my ignition/starter on my old Yanmar 3GM30. Sometimes, th e ngine started without any trouble, other times I got nothing, not even a click. I knew there must be a problem in the wiring, so I brought the boat to the yard. They fixed the starter, replaced the ignition button, and tested everything. Seemed fine. Worked once or twice - no trouble.

Then we left for a week-long cruise. First day, fine. Next day, the engine wouldn't start again. We were a few miles offshore with no wind, so I tried to short-circuit the solenoid to start her up. I had done this successfully a couple of times before, and although I knew this was not something you want to do often, I had little choice. After I I had the engine cranking, I closed the decompression switches, and then -Bang! We heard a loud noise, and then had black smoke billowing from the air intake. I knew that wasn't good. Called the towboat to nearby harbor. Spoke with a helpful diesel mechanic, who gave me the advice that killed my engine.

He said I might have bent a valve in one of the cylinders, and I shouldn't run it. I would have to sail the 20+ miles to our home, but he said if I needed to, I could run it very slowly for a few minutes to get into our harbor inlet, just not for a long time. He reassured me that it would be OK for a few minutes.

After a torturous fifteen-hour sail home in very light air, we started the engine for the last 1/4 mile to our mooring. Vroom! Started right up (with ignition button - the correct way). Though the engine was only running on two cylinders, we thought we were home free, but as we approached our mooring, we heard a loud snap/crackle & pop, and then the engine seized. I fear we wrecked the engine.

Our local diesel mechanic is scheduled to look at her this week. He said it doesn't sound good.

Question: Shoud I consider a rebuilt engine? Should I have mine rebuilt? Or should I bite the bullet, and buy a new one? Yanmar doesn't make the 3GM30, so I'm not sure the new 3YM will fit the dimensions available.

Needless to say, our sailing season has probably come to a quick end. What a mess...

[JimsCAL]

I have to agree this doesn't sound good. Just wait until the mechanic gets a chance to look at it. If a rebuild is possible it's going to be a lot less than a complete replacement. Taking the head off to see what's up would seem to worth it.

Good luck.

[CharlieCobra]

Having just heard the dreaded rattle rattle clunk a couple of weeks ago, I feel your pain.

[Stillraining]

Dont know a thing about the Yanmar engines..but shorting across a solenoid will NOT destroy your engine..getting poor contact while doing it will at the most slightly take some life out of your starters gear and the engines ring gear but were not talking major dammage here.

Dumping the compression releases probably had more to do with it but thats standard procedure for hand starting so it sounds to me like she had internal issues ( fatigued or faulty part ) and was ready to go in the first place. Tough luck on the dammage after running it after the Mechanic said you should be alright..Thats a tough call for any Machanic to make and i bet he feels equeally bad.

[Gary1]

How many hours on the engine?
It may have just been tired, but usually when something goes in a diesel, it's a rod bearing or you suck a valve.

As for rebuilding, almost any diesel can be rebuilt--your mechanic can have a look and tell you (if he's honest) what it'll cost.

A basic rebuild is rod bearings, main bearings, piston sleeves, piston rings and a gasket set. If you've never done anything to the fuel pump/injectors, I'd take them to a good injector shop and have them rebuilt, too.

That being said, really loud bangs followed by seizing up could be a broken crankshaft, and after eyeballing the prices for those (obviously made of gold or platinum), I'm not so sure it would be worth it. If the crank is broken, and you decide to rebuild anyway, make sure the mechanic has the block magnafluxed inside and out to check for hairline cracks. When a crank goes, it has a habit of cracking the webs between main bearing carriers, and that leaves you with a weak block.

good luck.

[Omatako]

Originally Posted by Gary1

A basic rebuild is rod bearings, main bearings, piston sleeves, piston rings and a gasket set.

Not all diesel engines have wet liners (sleeves) that can be replaced. I don't believe that Yanmar 3GM30 has. If the sleeve is badly damaged and it may be if a valve broke off and went walk-about, then the problem could be irreversible. I've bored out damaged liners and resleeved them but it's rarely a good solution and if the original sleeve is holed, forget it.

Oh, and if you're contemplating a rebuild, you will probably need more that just piston rings

Andre