G900 diesel overheat wont turn over

bog

Member
I was running the g900 down the road when all of sudden it got hot and started blowing water out of the radiator. I shut it off right away. But when i went to restart it after cooling down it wont turn over. It sounds like a piston is tight or something. The motor has not been run a ton after a rebuild. Maybe an hour. Someone started the rebuild 20 years ago and never finished it. I got the tractor and finished it. It ran fine, good oil pressure. It was not running hot, untill all of a sudden temp pegged and i shut it down right away. What might have gone wrong? What should i do now? Thanks.
 
Sounds like coolant is in a cylinder. Don't keep trying to turn it over or you could bend a rod. Check oil and see if there is coolant in it. You may have to pull heads. These MM guys can help, hang on they will respond more for you.
 
I agree. It sounds like you may have blown a head gasket and started pushing gases into the radiator. That will also allow coolant into the cylinder.

If the engine will move by hand (even a little), it is not likely a stuck piston.

If it is water in a bore, you maybe able to determine which bore by openning the closed exhaust valves one at a time and seeing if the engine will turn completely over by hand. The water should push out into the exhaust manifold.
 
It looks like it may be a stuck piston. I cant turn it over with a prybar on the ring gear. I was able to before this happened. Guess i will be tearing it down. The bad part was that i was returning the tractor to my neighbor that dropped it off at my place to get it running for him. I got it running after being apart for 20 years, but did not make it the mile to his place.
 
The heads were already on it. All i had to do was put the injector lines and manfolds on.
 
Remove your injectors before you try and pry the engine over. This will relieve any coolant in the cylinder and also will determine what cylinder head you may have to remove if you do have coolant in a cylinder. It"s called hydro lock. With the valves closed the coolant can not compress and it has nowhere to go. Most of the time it will leak down past the rings into the oil. Oil should look milky. If not hydro locked you may have to pull all the heads and look for a piston that is seized to the bore. Possible that rings were not filed before installed on pistons. But that doesn"t explain the overheat. The overheat would explain the coolant in the cylinder. A cracked head or blown head gasket will send pressure into the cooling system and close the thermostat or just have opposite pressure not allowing the coolant to flow. Hope this helps some.
 

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