30 yr old mdl4 onan. Only 500 hours. Repair or replace???

[Ted Smith]

My 30 year old 20KW MDL4 Onan only has 500 hrs but may have seized from lack of use. Like they say...use it or lose it!!! It's been a year since I ran it and it won't turn over. Tried the big wrench and it won't budge.It looks brand new but is suffering from lack of use. Problem is not the starter.
I always thot the 20KW was overkill. Thinking of replacing it with an 8 or 10 KW which would be much quieter. Is it worth the expense of fixing or is it smarter to replace??? Any suggestions would be appreciated.

[Passages]

Might be an easy fix. Soak some penetrating oil in the cylinders to free the rings from the side walls.

BUT- it sounds like you really want to replace the genny. If have the scratch, do that instead.

[oscarvan]

Yup, squirt some PB-Blaster in there....

[Boatsb]

Maybe just try it with a bigger wrench . Somethings gotta let loose. Why not enjoy breaking it.

Maybe a sledge hammer.

If its siezed it's in need of real work. Dont do it half assed.

[jim rosenthal]

Try MMO. If that doesn't free it up, nothing will. If you replace it, get a 12kW NL or Bollard Marine.

[ageless]

Depending on location, I may be interested in taking it off your hands should you decide to scrap it

[oscarvan]

Maybe a sledge hammer.

Ah yes, the ol' BFH.

[dottieshusband]

I got the jetski on top of my boat, essentially free. The PO said the motor was seized. And if I wanted the trailer, I had to take the jetski... It wouldn't turn over, although the case was intact. I removed the spark plugs, filled the cylinders with a light machine oil, let it sit a few days. Then took a wooden dowel and inserted down the spark plug hole, and moderately tapped each piston crown. After removing the dowel and spark plugs out to prevent hydolock, hit the starter and it spun like new. Replaced the plugs, and fired it up... runs good. In your case, remove the injectors, machine oil it, tap the crowns, and give it a try. Diesel fuel is a great lubricant, so seizing after sitting a year would be unusual, so it may really have issues. A bent rod or two from hydolocking would also prevent it from rotating.

[Boatsb]

Diesels run much higher compression and tighter tolerances.

I've not seen a diesel locked up and repaired this way. Gas motors yes. But always wonder what the inside of the cylinders are like. If theres a small bit of rust or pitting there will be long term issues.

[SKYCHENEY]

You will need at least 12-15kw to run everything on that boat. Don't buy a new generator that's too small. Much of the cost of replacement is not from a difference in size but the cost of taking out the old one and installing the new.