Yanmar- near disasters

[Piper'sGirl]

We had the strangest engine problem today when we went out for a sail.
Our Yanmar 12 GM. It hadn't been started in about 4 weeks, and when we went to start it, we couldn't get it to turn over. Sounded like something was going wrong with the starter? We hand cranked it, got it to start, let it warm up for about 5 minutes, and away we went...
UNTIL, minutes later the engine started idling high and brownish smoke started billowing out the exhaust. Worst of all, we couldn't shut the engine off- we pulled the engine stop button, turned the key, cut the gas... finally we put the engine in neutral and it stopped.
My partner is ready to throw the entire engine overboard and never leave the mooring again. help! Any suggests on what might be causing our woes?

[emeraldsea]

I finally got fed up with my YSE12 and pulled it out last fall. THey are a very simple and robust engine, that sips fuel. They are also noisy, have lots of vibration, and is underpowered for my heavy boat. I think your fuel pump needs an overhaul, there is a plunger that wears out in them.

[Boracay]

You don't give us much information about the engine (age, condition, service history) or your boat or what services are available to you but I would suggest that you have three choices.

Choice 1: Buy every book, tool and spare part that you can possibly need and keep working until the engine purrs.

Choice 2: Pay a repairman whatever he (or she) asks until the engine is fixed.

Choice 3: Replace the engine with a new one.

Having started with Choice 2, progressed onto Choice 1 and then finished with Choice 3 I can say that trying to fix an old engine is a mug's game.

[Alan Wheeler]

Two possibles. You have had engine sump oil make it's way into the intake and the engine has tried to run on engine oil. This can be due to a badly worn engine or stuck rings that have maybe corroded to the piston due to salt water getting back into the engine cylinder. That may have been why the starter could nto turn the engine over.
The other possible is the injector pump. But that will not be related to the starter not turning the engine. Plus they tend to allow an engine to "runaway" picking up revs till you think the thing will explode. Umm, and they can just about. They can do a lot of internal damage.

[Hud3]

Is your start battery dead (you said you had to hand crank it to start the engine)? I have a "Stop" button (solenoid operated), and the engine won't stop if the start battery is dead. Luckily I have a "Crossover" button that allows the house bank to substitute for the start battery.

[hellosailor]

I'm going to make a rash guess that your engine is old and worn. Diesel (not gas) got down past the rings and diluted the lube oil, and no one checked the lube oil to see how it was changing and "growing" past the fill point. Then when you shut the engine, it continued to pull the lube oil (now truly fuel oil) up past the rings and keep on running.

Diesels are quite happy to do that.

I would guess that your engine could stand a major overhaul, but you'd want a mechanic on board to make that decision.

If you have the time, look up "Mack Boring" they are a najor diesel outfit who also run "diesel engines for sailors" classes, and they can teach you in one or two weekends enough to really master you engine. You may still want to scrap it, have someone else work on it, or kill it, but a Mack Boring class will teach you everything you need to know to really understand what's happening in there.

[David M]

We can only guess. I would have a professional diesel mechanic look at the engine first hand who can then help you decide which of the three alternatives are best for you...repair, rebuild or replace.

I would not start replacing parts until you know with certainty the problem. That can get expensive when you start replacing good parts with good parts.

[Inlet Marine Services]

Well 12 gm is not a Yanmar model, is this a YSM 12 or a YSB 12 maybe. Single cylinder hortizontal motor. Its sounds like the rack stuck or something with the govenor. This motor if it is a YSM is 30 plus years old and most likely tired.

[Piper'sGirl]

Yes, I realized that ignorant mistake after posting. It's a YSM12, and it's 35 years old. Given all of the information we have both gathered (and thank you!!) we are thinking the engine either needs to be overhauled completely or replaced. My biggest problem is whether overhauling the engine is an economically sound decision. We can't afford a new inboard, and we don't expect to hold on to this boat for more than a few more years, but we are in Pamlico Sound and cannot get out Beaufort Inlet, or really off our mooring, without an engine (we are not the best or most experienced sailors). I'm wondering if it makes sense to get rid of the inboard, convert the space into something useful, and buy an outboard. Any thoughts?? Thanks for all of the great suggestions!!!

[GordMay]

What make/model boat?

[Piper'sGirl]

27' Watkins 1978

[GordMay]

Looks like an outboard might work on a Watkins 27', if neccessary.

[Inlet Marine Services]

We rebuilt one 2 years ago and parts at that time were very hard to get, we had bought some of the last parts in Yanmar inventory. Even at that the customer spent around $ 3000.00 then the other problem is room. Most all replacements will need 20 to 25" of verticle space. Alot of vessels were designed around that pancake motor and new engines will not fit with out raising the deck.

[Aqua Vitae]

"I'm going to make a rash guess that your engine is old and worn. Diesel (not gas) got down past the rings and diluted the lube oil, and no one checked the lube oil to see how it was changing and "growing" past the fill point. Then when you shut the engine, it continued to pull the lube oil (now truly fuel oil) up past the rings and keep on running."

This is the captain of Piper, lucky to have a first mate who cares so much about something I do. That said, here goes with a little clarification.....

The boat is a Watkins 27' 1978 with a YSM-12G engine. I checked the oil beforehand and did notice the oil level had risen some. The oil quality/ makeup had not seemed to change much though. Being an ignoramus when it comes to diesels, I plowed ahead with starting her up anyways. I hand cranked it for a while, but what ultimately started it was the battery, which is new. So, the rest of the story has been told accurately, but the smoke was blue, not brown. Burnt oil seems to have definitely occurred. The question I have is if I can get away with new piston liner, rings, bearing shells and a valve lap. Basically, an in-boat rebuild probably largely done by yours truly and the machine shop. OR, is it just not worth it to have an old engine with impossible to get parts that will probably break again soon (plus is loud, full of vibration and needs a paint job to boot).

And one more thing- I would love to have the satisfaction of using this thing as a mooring cause I hate it. Didn't someone once say that "Yanmar" means "throw into the ocean"?

[Piper'sGirl]

details, details....