2gm Yanmar has not run in 12 years – cylinder accesses for an endoscope & PB blaster?

[cadmus]

Is there any way to get a 9mm (maybe 7 or 8mm) endoscope in the cylinders of a yanmar 2gm? No glow plugs on the gm series, so I presumed not. But I figured I would ask.

Engine has not run in 12 years. So if anyone has a smooth way to get a PB blaster straw or a syringe tip in there please do speak up. I am all ears.

[cadmus]

I predict the following will be the next bits of information needed:

Yes, previous owner claimed to winterize it before his back got so bad he could not get up into her and there was antifreeze everywhere when I first saw her.

Yes, the typical rust and carbon buildup in the mixing elbow was bone dry when I surveyed it. No moisture in the rubber exhaust tubes. She was stored in a desert with low RH and very high to low temperature regime.

Sadly, yes, about a quart of water was in the base of the lifter muffler, yes I know that is bad. No, I can not tell if it is salt or fresh or antifreeze yet.

No, the fly wheel will not spin when I crank on it with a ratchet clockwise. I have not forced it too hard. I would rather lube the cylinders real good with PB blaster, then later some MMO + diesel. Possibly do an “over-fill” oil change. Then try to budge her gently every day until spring. Change all the fluids and approach it more seriously in the spring. Yes I also tried the hand crank. No I did not use the starter motor. (am I correct that the hand crank rotates counter clockwise while the crank shaft is clockwise?)


I wanted to get a good view in there before I started adding fluids or crank too hard on the flywheel.

(EDIT: aside from being totally stuck, the engine is immaculate!!! hahahaha)
(EDIT: endoscope is more like 7.9mm)

[cadmus]

Is there a good way to see if an exhaust valve is open in this stuck position?

[skipperpete]

Nope, the endoscope won't get past the pre-combustion chamber. Your best move is to dispel all doubt and simply remove the cylinder head and closely inspect the bores, piston crowns and valve seats.

[a64pilot]

Originally Posted by cadmus

Is there a good way to see if an exhaust valve is open in this stuck position?

Remove the valve cover and you can tell by spinning the engine and of course if it’s stuck you’ll know, cause a push rod will get real loose, if it’s stuck closed the engine will suddenly get real hard to turn and if you force it through it’s likely you will bend a push rod.
I have unstuck them before by removing the rocker arms and smacking them with a plastic dead blow hammer, be sure to smack the valve and not the retainer or you may compress the spring and the keepers fall out, it’s the way a poor man disassembles a head, use a socket to compress the retainer, smack it with a hammer and the keepers fall out and the spring is removed.

So is this engine stuck? Is this part of a pre-purchase inspection? Or is it yours?
If it doesn’t have glow plugs, you sure it has pre-combustion chambers? Those usually go together.

If it’s yours and it’s stuck, I’d pull the head, I assume it’s stuck because you said PB blaster, PB blaster isn’t what I would use to pre-lube, it’s what I’d use to try to break an engine free.

[a64pilot]

Oh and a stuck open valve will remain stuck open when the rocker arm assy is removed of course, removing that is real easy

[Disailor]

If it has been stored with low RH probably little rust 'tween rings & cylinder. A healthy dose of PBlaster wouldn't hurt. I shot mine down the injector holes. Followed by MMO/Sea Foam while the injectors get rebuilt. Checking for stuck valves is vital.



FYI: Read the results of a test that revealed a 50/50 mix of transmission fluid & mineral spirits beat all the commercially available penetrating lubes in terms of least amount of torque req'd to break free.

[flyingfin]

Are you buying the boat to flip or use? Will you trust your life with engine? Why not pull the motor and get a pro to re-build it for you, so you have a dependable machine and one less thing to work on. The rest of the problems on this boat will keep you busy enough

[oleman]

Originally Posted by flyingfin

Are you buying the boat to flip or use? Will you trust your life with engine? Why not pull the motor and get a pro to re-build it for you, so you have a dependable machine and one less thing to work on. The rest of the problems on this boat will keep you busy enough

My issue is that hiring a pro to rebuild the engine is probably more expensive that the cost of the boat.
Personally, if I wanted this boat and intended to use it. I would remove the engine, disassemble it in a shop environment and start there. With good access an engine that small should be easy to work with if parts are available.

[captlloyd]

It’s always nice when we answer a posters question. He is trying to get an engine unstuck, not asking about rebuilding an engine. Stay on track.

[Mike Banks]

What Skipperpete said.,

[Wotname]

Originally Posted by a64pilot

............
If it doesn’t have glow plugs, you sure it has pre-combustion chambers? Those usually go together.

.........

For general information, the Yanmar GM series along with the GMxx, QM and xSx series all have pre com chambers and no glow plugs.

[Wotname]

A poor man's way of introducing some lube fluid into the cylinder if the injectors are too difficult to remove is to flood the inlet and exhaust manifolds with an aerosol lube - there is a fair chance at least one valve is open enough in each cylinder.

But really, what skipperpete said in post #4 is the best approach.

[NorthCoastJoe]

I would go with Skipperpete's plan. The engine is easy to take apart and while there clean out the raw water passages. Even if you only pull the head and do a valve job it will be worth it. I would bet the cooling passages are plugged in the head up and that the exhaust valves are pitted on the backside from the water in the muffler over the years.

I rebuilt one of these recently, if you have any questions I will be around all week.

[NYSail]

Just a garage mechanic here but Doesn’t pb blaster destroy gaskets?
Also yanmars have no glow plugs and do have pre-combustion chambers. Also doesn’t this engine have a decompression valve?
Friend recently go an old yanmar spinning..... first drained all old oil , pulled the injectors and poured in a 50/50 mixture of acetone and trans fluid and let sit. Then pickled engine with mmo..... after about 3 weeks he attempted to hand crank and it began to turn..... everyday he would move it a bit more until finally she broke free. Engine runs fine but he said he eventually will tear it down.
Good luxk