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.

 

[IH3444]

Head should also be checked for warpage, and do some internet searching for a possible Yanmar head gasket set for the upper end. Might as well grind the valves while it is off.

 

[mobilus]

I found a crack in the head, running between the injector port and a valve seat. Guess I need to start looking for a head. Anyone got an extra one lying around? I'll call the owner tomorrow and see how she wants to proceed. Thanks for your help to date. You're all invaluable sources of information!

Mobilus

 

[mobilus]

http://www.tractorbynet.com/photos/showphoto.php/photo/4565/sort/1/size/medium/cat/500/page/

http://www.tractorbynet.com/photos/showphoto.php/photo/4563/sort/1/size/medium/cat/500/page/

http://www.tractorbynet.com/photos/showphoto.php/photo/4564/sort/1/size/medium/cat/500/page/

 

[RobJ]

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.

Part 1 is ok, part 2 i would not do. re-torque the wheels and such, leave the engine parts alone. No one takes their tractor, truck, etc back to the dealer for a cylinder head bolt check.

One ugly looking head there, good luck on a replacement, got to be used parts out there like there is for Kubota. Search my posts if you like, I changed out the head gasket on my kubota early this year. I think I'm gonna re-ring it this winter.

JMO,
Rob

 

[IH3444]

Cylinder heads are repairable, but only by someone whom truely knows what they are doing. The valve seat rings are removed, the head prewarmed, welded, then returned to oven to cool for 24 hours. Then checked for warpage, straightness, and pressure checked. New seat rings installed, checked again. They are repairable, but of course still a bit iffy. You maybe able to find one on the web.

 

[mobilus]

Thanks, Rob and IH3444. I'll still just wait and see if the owner comes up with a suitable replacement. I spoke with a machine shop owner and he told me basically the same thing that IH3444 did, but the cost would be higher than if we found a salvage head. We'll see.

 

[ScottAR]

Fredricks

A customer/friend of mine has had good luck with these folks with his yanmar tractor. A rebuilt head for his 1700D was about $700 exchange.

The engine plate is on the left side near the oil pan rail.

 

[Renze]

Is it direct injected or does it have a swirl chamber in the head ?

When i rebuilt the heads of our 5245, the shop guy said that any direct injected head was no problem: an aluminium head was skimmed with a kind of mill with a small chisel, and a cast iron head with a grind stone.

He said, skimming indirect injected diesels was a *****, as automobiles usually have their hardened swirl chambers in a soft aluminium head. this costs about 5 times as much as a cast iron, or pure aluminium head.

grinding the valves in the seat cost me 3 euro per valve: skimming was 10 euro per head (Zetors have individual heads) and the compression test was 50 euro per cylinder.
The head gaskets cost me 10 euro each, between 4 to 6 euro for the valve cover gaskets.

 

[mobilus]

All this has been for naught...the lady that I've been working this for choked on the idea of spending a grand on a tractor worth maybe only four times that amount. So I put it all back together, and I will haul it up to a tractor dealer that she deals with. He's going to take it in on trade towards a larger tractor. Not sure what she's going to get.

Everything is a learning experience, and at least I gained some knowledge during this deal. I was looking forward to completing the job though. It's nice to repair something and fire it up afterwards...

Thanks for all your help. No doubt I'll call on your collective knowledge again.

Mark

 

[zzvyb6]

Moby:

With your talents and demeanor, I'd suggest you go work for that tractor dealer. Maybe even offer to fix that tractor for him as a first job.

I can understand her decision and your efforts may even have been rewarded, but I'd be missing the sense of accomplishment that such projects deliver. Turning broken or maimed machinery into healthy running stuff puts a warm fuzzy in my toolbox. Should have been a doctor....