Advice Sought. Engine Seized after installing Injection pump

[seabreez]

Originally Posted by Jack C

I had a bad gas of muck growing in the fuel system of my Yanmar 3ym30. EDITED..... Considered a stuck starter motor. But that would not seize the engine. Alternator and fresh water pump and water pump">raw water pump are belt driven. Eliminated them....Please any serious suggestions? I am running out of ideas here.

If it was my engine, the next thing I would do is remove the starter and you will feel the drive click away from the seized position... If you do not hear this, do nor worry. Use a pry bar or a heavy screw driver and try turning the flywheel through the starter opening. I doubt very much the pistons would be seized. For the crank to be seized, you would have had to run the engine dry of engine oil. Running the engine with diluted oil and diesel mix.... I doubt you would have spun a bearing and seized the engine. Try this and come back with comments...

[kapnd]

Originally Posted by Stewie12

Probably the seal on the injector pump allowing diesel into the engine was the cause of the original problem. The seal needs to one from the manufacturer.

I once had an injection pump rebuilt that came back with a shaft seal installed backwards, allowing diesel fuel into the sump via the gear train.
As for the seizure, I’d walk back to the woodruff key incident. There might be a foreign object lodged in the gear train.
Try turning the engine backwards, possibly with a big screwdriver on the flywheel gear.

[seabreez]

Originally Posted by double u

@seizure: I wonder if an engine seizure can even occur after it has been stopped (apart, o0f course, by water entering). Wouldn't an e.s. show up as engine is by itself quickly reducing revs until standstill? Just guessing...
timing gears would jam without a big bang when running? Same with a stuck valve: no nasty sounds?

An engine will not seize while stopped. During a high speed rev... no load a valve can float and the lock can become free and the valve can drop in the cylinder. To check this... take the valve cover off and check for a loose rocker or valve spring. The valve is opened and bent by the piston. You would not have heard this happening. Next step... go deeper and remove the cylinder head... keep this going... I am curious to see the end...

[RaymondR]

The most likely cause is that whilst you were turning the engine to bleed all the injector lines you pumped the exhaust system full of sea water and some has got into the cylinders and caused corrosion.

[Jack C]

Originally Posted by RaymondR

The most likely cause is that whilst you were turning the engine to bleed all the injector lines you pumped the exhaust system full of sea water and some has got into the cylinders and caused corrosion.

Sorry, no, I checked the exhaust system. Muffler had minimal water. Also I closed the raw water seacock after running so no syphoning into the muffler.

[Jack C]

Originally Posted by seabreez

An engine will not seize while stopped. During a high speed rev... no load a valve can float and the lock can become free and the valve can drop in the cylinder. To check this... take the valve cover off and check for a loose rocker or valve spring. The valve is opened and bent by the piston. You would not have heard this happening. Next step... go deeper and remove the cylinder head... keep this going... I am curious to see the end...

Great explanation. Best so far. Makes sense. I plan to take off the valve cover this morning and check. I will keep this going and take pictures.

The folks on this forum are great. I appreciate the ideas.

[Jack C]

Originally Posted by Jack C

Great explanation. Best so far. Makes sense. I plan to take off the valve cover this morning and check. I will keep this going and take pictures.

The folks on this forum are great. I appreciate the ideas.

Latest update.

Removed the rocker cover. No stuck valves. Piston #2 is at top. 2 closed valves. I see the clearance on the top of the valve stems. The push rods rotate.

Everything looks great. There is lubrication.

So I guess no broken, or bent valves or loose springs etc.

Still seized. I added liquid wrench again.

Started to get access to the idling gear. Tried to remove alternator belt. Finally got the alternator loose. I cannot get the belt off. There is not enough movement. The belt is just slightly loose. It appears that the previous owners had installed a belt that is too small. They must have levered it on.

Next is to pull the crankshaft pulley and remove the gears cover and look for a jammed gear. I may have to pull the idling gear.

I checked the inspection hole that gives access to the flywheel. Nothing out of the ordinary.

Now down to:

1. Jammed gears. Wont be surprised after seeing a too small belt installed.

2. Seized pistons

3. Seized gearbox

Anybody got any other ideas?

[RaymondR]

#2 is the most probable, you only need one piston to be seized.

[Jack C]

Originally Posted by RaymondR

#2 is the most probable, you only need one piston to be seized.

Keeping up with daily doses of liquid wrench.

In a few days I will try transmission oil with acetone, 50% each.

By taking out the idling gear I should have problem isolated to pistons or seized crankshaft bearings.

Or seized gearbox. ??

[P8R2012]

Maybe it is hydrolocked , drain all fluids and see if the engine spins.

[Cheechako]

Can you just remove the injection pump and see if the engine turns?
I can't understand how a piston is seized.

If you did temporarily hydrolock you may have bent a rod. Or the full oil reservoir could have caused a rod/piston issue also. Would that lock the engine up though?
That's two things in the favor of "bent rod."

At this point removing the head is what ....a half hour job? I would start removing anything that can block the engine from turning. First: peripherals. Injection pump, starter, etc

[Talbot]

Can't possibly be the gearbox ot the engine would run in neutral

[double u]

only thing I come up with after all the posts: blocked by some hardware, eitehr dropped or broken (& now for the "furthest fetched" idea: in the early phase of the V8 Cosworth F1 engine [DFV] they had problems with the gear train of the camshaft: due to vibrations teeth on one of the gears would break, & if two adjacent tee thbroke the whole works stopped dead...)

[Don C L]

Originally Posted by Jack C

Keeping up with daily doses of liquid wrench.

In a few days I will try transmission oil with acetone, 50% each.

By taking out the idling gear I should have problem isolated to pistons or seized crankshaft bearings.

Or seized gearbox. ??

Personally I'd wait on adding more corrosion busting fluids. It does not sound like you have a corrosion problem.

[double u]

imho THE thing to do is:
rip the engine out & then apart!
If you ever want to have peace of mind again...
(I remember entrance to Ashkelon marina in onshore 25kn + onshore swell as no place for doubts about one's engine...)