John Deere 850 head gasket

[mobilus]

I'm about to pull the head on an 850 to replace the head gasket. Any helper hints or suggestions before I get started? Anyone know the torque value for the head bolts?

Any helpful advice is greatly appreciated!
Mark

 

[BTDT]

Welcome to TBN Mark. Why are you having to pull the head? Do you have a parts/repair manual for this unit? Get your camera ready (TBN'ers like pictures ). If the unit runs, might want to clean it up prior to dis-assembly to remove dirt, grime, etc.

 

[mobilus]

Thanks, BTDT.

I do some part-time work for a rancher/farmer lady, and her Mexican field hands had ran it hot. Instead of telling her right away, they kept filling it with water and it kept disappearing...imagine that.

Anyway, it is the same size as my Kubota and I thought I'd be up to the task. I'm a good wrench by most people's opinion (20 years as an F-16 crew chief) and she liked the way I treated my equipment when I hired on to bush hog a pecan orchard for her. So that's why I'm doing this.

No, I don't have a manual for it, but I'll look. The biggest thing is the head bolt torque, which I'll have to find. Oh, and yes, I usuallly power-wash equipment before I work on it...and did that tonight on this tractor.

Thanks,
Mark

 

[RickB]

Take the time to send that head out for a pressure test. It may well be cracked.

 

[mobilus]

I definitely will. I'll take it off the tractor this afternoon, and take it with me the next day to the machine shop. Thanks!

 

[DK35vince]

This is from my JD 850 service manual.
Torque- cylinder head to block
Initial (43 ft-lbs)
Second (87 ft-lbs)
Final (116 to 130 ft-lbs)

 

[mlauk]

There is a torque sequence on heads starting on the middle bolts heading outward alternating side to side. Diesels usually need to be retorqued after they have run a little bit.

 

[mobilus]

Thank you, Vince and mlauk!

I called the local John Deere parts counter today and was a little shocked at the price of a head gasket alone = right at $100, with the whole upper gasket set at close to $200. I guess I better find out what the head looks like before I order...if it's cracked, we might have to re-evaluate the situation at hand.

 

[Inspector507]

Thank you, Vince and mlauk!

I called the local John Deere parts counter today and was a little shocked at the price of a head gasket alone = right at $100, with the whole upper gasket set at close to $200. I guess I better find out what the head looks like before I order...if it's cracked, we might have to re-evaluate the situation at hand.

If you send a PM to LMTC here at TBN, he'll send you a PDF aftermarket parts catalog for the 50 series tractor. He has a good source for the aftermarket parts listed in his catalog which I understand are becoming hard to get from the OEM dealer.

 

[mobilus]

Thanks, Inspector. I sent one, I hope I did it right.