My 8hp Yanmar won't start

[Loki]

I've got a single cylinder, 8hp Yanmar that has started the first time, every time, until now.

When the starter engages, the engine turns, while making a horrible screeching sound, but does not turn over.

Here's what I know and thought of to check so far:
- The starter is new, is fully powered and turns the engine
- the batteries are at full strength
- the air intake is clear
- fuel pump was tested and works properly
- unable to budge the engine with the hand crank - even when standing on the crank handle
- manual compression release lever is frozen closed and broke off when I tried to pry it open

My guess is that I'm looking at a compression issue, but have no idea of where to go from here. Any thoughts or suggestions?

[DeepFrz]

Pull the fuel injector and check for water in the cylinder. Sounds like you have a water lock problem. Your post is a little confusing in that you say the starter turns the engine over but you can not manually turn it over. I suspect a typo somewhere.

[Loki]

Deepfrz,

Thanks for the suggestion. I'll check for water in the cylinder. Also - it wasn't a typo. I literally cannot budge it by hand, but the starter is able to turn it. I can't be sure, but it doesn't seem like it turns as easily as when it was running properly.

Loki

[bil56]

I confirm deppfrz's version,
probably a large water input in the cylinder.
check the oil,
risk of damage, you'll have to disassemble the cylinder ...

[DeepFrz]

When the starter engages, the engine turns, while making a horrible screeching sound, but does not turn over.

Well, I'm sorry to hear this. Sounds like you have a very serious problem. You may be wishing that the starter actually didn't turn the engine over. By the way, how long did the engine sit since the last time it was used?

I take it that you have checked that there is oil in the sump?

Anyway, try squirting some oil into the cylinder when you get the injector out and then turn it over a few times. Possibly the cylinder/rings are rusted.

If everything checks out when you get the injector out then maybe the starter or transmission is the cause of the noise.

A long shot is that something being driven by the belt is causing the problem. That would be alternator or water pump. I suppose it could also be the fresh water pump.

[Loki]

Bil56,

Thanks for your response. I appreciate the advice.

Loki

[Loki]

DeepFrz,

Believe me, I wish it was the starter. I did check the oil and did not find any signs of water on the dipstick. I'll try draining the oil and doing a more thorough check. The last time we ran the engine was last September. Rust may be a factor - the starter had frozen and was recently replaced.

I haven't considered the transmission as the potential culprit, and not sure how to check that. I am quickly reaching the limits of my already limited mechanical abilities...

Loki

[BOATDOCTOR]

Get the injector out and turn the engine by hand. It should turn easily, except for what you should feel as flywheel weight. If you get drag or a noise, stop turning it and get experienced or professional help. Same goes for if any fluids shoot out of the injector's hole when turning the engine. Checking condition of the oil "further" at this point is only going to get you further than when you checked the first time if you note for certain it smells like fuel, or the first thing out of the pan is water. Just draining a cup will tell you this. Loosen the lines on the injector and remove them from it... remove the hold-down bolt and clamp and then work the injector out of it's hole in the head. Turn the engine... What happens?

[Loki]

I wanted to thank everyone for the great tips and advice. The engine is running again. There were actually a couple minor issues that needed to be dealt with. First of all, since the engine had not run for many months, the lack of lubrication caused the piston to stick in the cylinder. Removing the head remedied this issue and the engine was able to be easily turned. The second issue was fuel related. Rebuilding the fuel injector solved this issue and the old Yanmar is again purring like a one-cylinder kitten. Thanks again to those who offered advice and suggestions, and especially to my new friends at H & H Diesel in Tacoma, who managed not only remove the lodged injector (without mangling it), but rebuilding it as well... in a single day.

Stay out of trouble.

Loki