Yanmar 3ym30 will not budge! Help...?

[jellis23]

My 3 cylinder yanmar is seized...

Here's the story:

Boat sat for 2 years on the hard and i finally got her back to operating condition as we're considering moving back aboard. I had about 10 gallons of fuel in the tank that i DID NOT DRAIN (oops) but siphoned to make sure it was clear and added new fuel. looked good. changed Racor prefilter. took sailing. left motor running while i tested the rig. tacked the boat and all the sludge in the tank went right to the pickup. filter clogged, motor sputtered to a stop. Sailed to the mooring, changed the prefilter and filter on engine, drained ALL the fuel and the boat sat for a few weeks till i could get back out to try and start it(shouldn't of let it sit with that junk in it). Would not turn over, but not seized, each crank yeilded a quarter turn of the crank or so. Finally no more budging. swapped the starter with no luck and finally removed the glow plugs to release compression. still no budge by hand. Sprayed penetrant into cylinders and removed valve cover to push on valves. All moved, rods are straight.

Here are my questions:

Anyone know if there is something else mechanical that can prohibit the motor from turning over? Could it be the injection pump or is it something more devastating within the block? Any troubleshooting advice or suggestions?

I feel like an idiot for letting the motor sit with that junk in it.

Any help much appreciated. You guys are great.

[deblen]

RW pump? Will eng. roll backwards by hand?Use socket wrench on crank pulley-GENTLY. / Len

[a64pilot]

Sounds like a hydraulic lock, does it have decompression levers?
Never mind, you had the glow plugs out, if it were hydraulic lock, that would let the water out and the engine would have turned over with the plugs removed


Sent from my iPad using Cruisers Sailing Forum

[hpeer]

It's pretty hard to imagine dirt in the fuel pump jamming the engine. I've gotten sludge bad enough I had to take the pump off and have it cleaned, but the engine still spun over.

My guess, or more rightly my observation is that perhaps the engine did NOT sputter to a stop due to dirty fuel, something else went wrong at that time and the dirty fuel is just coincidence.

What are you using to turn her over?

Hopefully someone more knowledgeable than me will offer better advice.

[Tellie]

Could be a hydraulic lock, which can happen when over cranking a diesel, but what kind of voltage do you have?

www.HaldenMarineService.com

[leftbrainstuff]

Try rotating the crank.

Is the starter not jammed?



Sent from my SM-N900T using Cruisers Sailing Forum mobile app

[deblen]

He removed the glow plugs & the valves are free,so it shouldn't be waterlock?.
Gotta be something run off crank or camshaft.That leaves inj pump,starter,?

http://j30.us/files/J109/Yanmar-3YM30-Parts-Catalog.pdf

[hpeer]

If he is super lucky he has a pot line wrapped on his shaft.

Just do a quick dive to check it out!

OK, I'm gonna bet 50¢ on this one, I'm feeling lucky.

Any takers?

Try putting it in neutral and then turning the crank. That's exactly the kind of thing I would do, be so worried and fixated about the engine I would forget the simple and obvious.

But, hey, that's just me!

Good luck.

[deblen]

hpeer Excellent detective work!! 'spose he 's still in gear?? / Len

[jellis23]

Wow, thanks guys for all the input.

The engine will not budge either direction (socket wrench on crank pulley)

The boat is now out of the water and i have tried turning the prop by hand while in gear but now that i think about it i did NOT check if the prop free wheels while in neutral. If i can not get neutral to disengage the shaft That would be an issue in the gearbox preventing turn over, right? Hard to imagine how that'd happen but i will check. It definitely ran rough for about 2 minutes rocking roughly on the mounts before stalling.

Tellie- per voltage i had 12.6 on a newer starting battery. I was definitely hard on the starter as it went from SLOWLY turning over to becoming hard locked. that got me thinking there was possibly water in a cylinder that could not be compressed any more but removing the glow plugs should have relieved that, right? I also was able to get all the valves to move thinking there could be interference. I also replaced the starter thinking it was the issue but should i pull it out in case it is not retracted?

[Neptune's Gear]

Go right back to basics. Put in neutral. Can you turn the prop? (is the gearbox seized??) remove starter, can you turn the engine with socket? Unlikely crap in the fuel will seize an engine. More likely an internal issue - water leak, broken piston/rod/camshaft. Once eliminating the gearbox, remove the accessories one at a time and test each time. If it is internal, the accessories had to come off anyway!

[Scout 30]

This really sounds like water in a cylinder. Bad fuel shut it down & continuous cranking in an attempt to restart flooded it. Before tearing it apart how about pulling the injectors, opening the compression release & then trying to turn it over. Also, did you check the oil. If this is due to water some would usually be in the oil. If it looks like a milkshake that's your problem.

[jellis23]

Thanks Neptune's- Back to the basics, It's good to step back and have a checklist to start with the most basic possibilities instead of jumping to thinking it's a bent rod or worse. i will check it out and report back.

I will start with the gearbox then the starter and then IP. Is the injection pump gear driven? Anyone have suggestions for disengaging it and keeping the engine in time?

[Hard Rock Candy]

The twenty horse 2 cylinder Yanmar drives the injector pump directly off of the cam. in other words, the pistons on the pump are lifted with special lobes of the cam. No one has mentioned the simplest thing. That could be, one of the pistons is rusted into the cylinder. It does not take much water to do the job and you did say that after working on it you left it sit for a while. You may have to remove the head on this one. They are a really simple engine to work on. Mac

[hpeer]

Your injection pump is driven off of your shaft, see fig 9 in the parts manual above.

Real quick look says it is directly driven, that would make it a 1 to 2 ratio, two turns of engine are one turn of pump. The 4JH has an idler gear in the middle, the overall ratio is 2 to 1 but the ratio of each gear is different. You need to be sur of that before taking the pump off. Don't ask how I know.