850 Won't Start

[Republic of Texas]

I have verified that it is coolant coming out of the exhaust. I pulled the compression adjustment and spun the motor over until the water appeared to stop coming out. Then I put the compression adjustment back to normal and spun the motor again.

This time, the motor turns over and tries to start. No more clunking/locking up. At this point, I do believe that the head gasket was blown when I let the motor overheat. I have ordered a head gasket from the dealership and it will be here next week.

Question: I read about needing to have exact torque on head bolts. What all should I replace after I take off the head? I've never worked on a tractor before, so if someone could just point out a few things to look for and double check, I would be highly appreciative.

Any additional advice will be greatly received. Thank GOD for this forum!

[Mechanos]

I have verified that it is coolant coming out of the exhaust. I pulled the compression adjustment and spun the motor over until the water appeared to stop coming out. Then I put the compression adjustment back to normal and spun the motor again.

This time, the motor turns over and tries to start. No more clunking/locking up. At this point, I do believe that the head gasket was blown when I let the motor overheat. I have ordered a head gasket from the dealership and it will be here next week.

Question: I read about needing to have exact torque on head bolts. What all should I replace after I take off the head? I've never worked on a tractor before, so if someone could just point out a few things to look for and double check, I would be highly appreciative.

Any additional advice will be greatly received. Thank GOD for this forum!

I hate to say it, but I've never heard of a head gasket just "blowing" because of an overheat. I am more suspicious of a warped or cracked head or a cracked block. I certainly hope I'm wrong, though.

[Mechanos]

I'm curious about this compression release. I am not familiar with this device and was just wondering if my 955 has one.

[K7LN]

I hate to say it, but I've never heard of a head gasket just "blowing" because of an overheat. I am more suspicious of a warped or cracked head or a cracked block.

I'll second that, but I think the point got missed.

..... Be aware that once the head is off, you need to check it for cracks and flatness. Also be aware that your injector(s) sealing will probably need attention.

[Mechanos]

What engine is in the 850? Is it covered in the CTM-3 manual?

[Republic of Texas]

What engine is in the 850? Is it covered in the CTM-3 manual?

The engine in the 850 is the 3T80J. I looked through that manual and I did not see this engine mentioned.

[Republic of Texas]

I'm curious about this compression release. I am not familiar with this device and was just wondering if my 955 has one.

The "compression release" is the only name I know to give it. I'm not sure what it's actually called, and I'm pretty sure that due to my inexperience, I am butchering the name and the intent of this device.

I will add an image in an hour or so.

[Republic of Texas]

I'll second that, but I think the point got missed.

If I am missing something, please let me know. All information will be greatly received and appreciated.

[K7LN]

If I am missing something, please let me know.

It's just that there may be more than a bad head gasket. The head needs checking for cracks and flatness along with the point of checking out the injector sealing since you had coolant squirting out of them too. Otherwise, nothing new to add.

[Republic of Texas]

Video Added

Attempted to start. Almost started. Decided to check coolant level after this attempt. Radiator had extreme pressure when cap was released. Coolant found to be low.

Finally got it to start. Here's a video of what appears to be coolant coming out of the exhaust.

Video:
John deere 850 Head Gasket - YouTube

I feel more confident that it's a head gasket, but not 100% until I see it. Should I take the head in and have it checked regardless? While I have the head off, what else should I look for?

Thank y'all so much for the help. Much appreciated.