Yanmar 2GMF lock up

[Jammin jr]

Hey all. I have s problem with my engine. It will turn free by hand in either direction for 3/4 of a rotation and then hits something solid. I can hear the compression with the levers down for the little it turns. I can also hear when it stops kind of a dull heavy thud if that makes sense
The prop turns freely by hand. It also turns freely in gear by hand which seems strange.
Anyone ever have this happen?
I should note I just got the boat as a project and it has not been run for years.
Thanks for any insight.

 

[lee oakley]

hello, if you don't have compression and it makes 3/4 rotation it's one of two things. Out of timeing or a bent valve

 

[Jammin jr]

Ok thanks much. I'll pull the valve cover and take a look. I should be able to see all 4 valves at least move some. If one is stuck or bent, it won't move and if they do move it can't be the timing gears.
Is it normal to be able to turn the prop while the transmission is in gear?

 

[lee oakley]

yes prop will turn but not freely. If the gear is engaged it may turn freely in one direction not both. As far as a bent valve if your valves move then the engine is out of time you should bring #1 to tdc. and check to see that time mark is correct

 

[kloudie1]

With both cylinders compression released, will it turn?.. If cylinders have a little water in 'em, it will do that.. with both decompress levers pulled, it should turn over and expel the water out of the intake, if I remember correctly.. take off the air cleaner .. One of the valves may be in a place where the decompress lever will not open the valve.
May have gotten that way from cranking a good bit with the seawater pump filling the exhaust..

 

[Jammin jr]

It will turn 3/4 of a rotation with the levers up or down. I'm thinking there is a stuck valve. The engine was installed and test ran then the boat was stored on the hard for maybe 10 years before I got it last week.
I'm going to pull the valve cover in a bit and see if there is any movement in the valve train at all.

 

[kloudie1]

Yup.. pull the cover .. Stuck valve is probably a good case! Should be obvious when you can see the mechanism.. Good Luck..

 

[Jammin jr]

Thanks all for the help. I'll let you know the findings.

 

[Bill Roosa]

Can't be water as the water will not make a dull thud and with continued effort the water will leak past the piston rings.

 

[Jammin jr]

Correct Bill also even with the compression levers up, it hits something. If it was water, it would push out with the levers open. I'm pretty sure it is stuck valves.

 

[Jammin jr]

life is good!!!! It was a stuck valve. I popped the cover off and could feel the thud was the pushrod hitting against the rocker arm on the front valve. believe it or not, a guick shot of blaster on the valves and rocker arm and instant result. she rolls over like a champ. Thanks for pointing me to the problem. I hope I can help the next guy along.

 

[kloudie1]

Good ! Fingers crossed that valve seat is OK..

 

[Jammin jr]

Should be, it was stuck closed. Must have been varnish on the stem as it was instant fix. The blaster didn't even need to soak in. Everything was very, very clean in there so I have to believe it when I was told the engine was a fresh rebuild when installed. They literally installed it, did a test run, then she sat in storage for 7 years.

 

[lee oakley]

Glad I could help! Was pretty sure of it with your description

 

[Jammin jr]

Thanks for the help Lee! I hope I can pay it forward.

 

[lee oakley]

your welcome, be careful though just because spray freed it up doesn't mean it's fixed

 

[lee oakley]

But then again sat for 7 yrs! Just give all the valves a good shot of penetrating oil ya should be good to go

 

[Jammin jr]

We have engine!!!!!! I got her running today. Took a bit of fusing, but in the end I won. Lots of black smoke but no zoom zoom at first. I hit her with a shot of starting fluid and she fired off for several seconds. After 3 more tries and short runs, she fired and kept running. Only ran for a minute due to no raw water, but the antifreeze never even got warm so I could have let it go a bit longer. Big big sigh of relief here!!!!!