Yanmar 3GM35F Intermittent Out-of-Control Revving

[never monday]

this thread so far has been like going to the doctor and saying you have high blood pressure. When the doctor asks you what the reading are. You say "I don't know, it's just high"

[Gnitfar]

Originally Posted by never monday

this thread so far has been like going to the doctor and saying you have high blood pressure. When the doctor asks you what the reading are. You say "I don't know, it's just high"

Is today Monday? ....OK, I won't comment! LOL....

[unbusted67]

Originally Posted by never monday

this thread so far has been like going to the doctor and saying you have high blood pressure. When the doctor asks you what the reading are. You say "I don't know, it's just high"

Please stay off this thread.

[Tellie]

Originally Posted by unbusted67

Please stay off this thread.

Just my 2 cents Unbusted. I've been reading Never Mondays posts for a few years now. He certainly doesn't need me to defend him. But I would suggest if you want to get to the bottom of your problem, far from help, not to summarily toss aside his opinions no matter how he delivers them. What he is posting makes sense. He may not get invited to a debutante ball, but you have no need for a debutante in your engine room.

[Solitude]

UB if you are going around tightening up fuel lines and machine screws resist over tightening bleed screws. I have read a few threads on people stripping these on Yanmars.. Do you have a shop manual? I doubt you have glazed any cylenders in a short time of running at 1800. Plus if you were running up the engine for periods of time you should be fine.

I don't think your at the run away point if you can throttle down and shut down. I am not a professional mechanic but isn’t the governor controlling max rpm. Could this be a source of trouble?

[never monday]

Originally Posted by unbusted67

Please stay off this thread.

please answer my max RPM no load and under load question. Then we'll be able to make an educated guess instead of a WAG

[cantxsailor]

I had a similar experience when the guvenor return spring broke. The engine revs seemed to increase with the vibration of the motor until I yanked the throttle back. This was not however on a boat but an old dozer I was learning to run years ago. A replacement spring cost about a buck and it never reved way up again, YMMV.....m

[sigmasailor]

What do you exactly mean by 'running away'. Most, if not all, diesel engines have some sort of governor controlling and limiting engine RPM.
Your problems sounds more like a faulty governor (if it is even that); it really would help if you answered never mondays (valid) queries for more info.

I do not believe you had a real runaway engine. Believe me I've seen one; we only managed to stop it by putting someones overalls into the air intake. Diesels can start running (away) if lub oil is sucked in via bad turbo bearings or manages to find other ways into the intake (e.g. valve seals). It is a little rare. If it happens you will not be able to stop it with your normal fuel cut off lever or button.

I guess it would also run away of the IP malfunctions; judging from the info so far I think this is not the case.

[Chief Engineer]

Runaways are very scary indeed.....I recently had a customer who overfilled his Yanmar and Va-Freakin-Room.......It was an engine I installed for the previous owner about 150 hours ago.

The others were Detroits....that so-called engineers pharted around with

BTW DDC don't really like to be shutdown via the emergency stops too often

[unbusted67]

I will check the rpms under load and no load now that we are back in the barn (SD) and within range of Seatow if need be. It really doesn't sound to me like we are having a runaway issue. It's not like the engine is out of control really, it just starts to - as the title of the thread states - rev up a bit. We did, happily, get back to San Diego in one piece, albeit at low rpms and motor sailing. Baja was a ton of fun.

[Captain Bill]

If this engine had a prop on it with a rubber shock hub, the problem might not be the engine or transmission at all. I didn't see anywhere in the thread where you mentioned the type of prop you have. Any chance you have a prop with a rubber hub insert?

[Highlander40]

Just a short note about tightening up fuel line fittings.
Rather than over-tighten a banjo bolt and break it, replace the copper washers.
I think that they are supposed to be replaced every time the bolt is loosend but who does that?