JD 950 engine rebuild

[83regalsx]

Hi everyone.
I recently purchased a ‘86 950 with a 3t90j. I’m a mechanic by trade and I got it for a song knowing it had some problems and a lot of hours (3200 hours). The head is cracked and while it’s off I’m taking the opportunity to put pistons and liners in it. I have a rebuild kit from weavers coming and I have a few questions.

What have others used on their liners seals? I see a few others here have done 3t90 overhauls. the factory liners definitely had some type of sealer around the top o-ring but everything I have read just says to lube them.

Thanks in advance for any input. I will post a few pictures where I’m at so far.

 

[83regalsx]

 

[83regalsx]

 

[TimberHole]

The overhaul manual calls for a JD lubricant on the o rings. It’s some slimy stuff. I can’t get to my bottle currently as I have everything covered for a project I’m painting. You going to repair the cracks or replace the head?

Also, the JD rings were far superior to any aftermarket options I found. The markings on the rings were an exact match for those removed. I didn’t think much of the aftermarket head gaskets either so went with Deere. Much better looking gasket although a bit more pricey.

Edit: There is no sealer on the o-rings, just a lubricant.

 

[rScotty]

SNIP

Thanks in advance for any input. I will post a few pictures where I’m at so far.

Re the liners. Yanmar used to recommend that the liners be put in with lube and no sealer. I'll have to go do some digging to if I have any notes on installing liners.

Looking at the pictures the liner that you pulled out has a lot of erosion. What do you think caused that?
rScotty

 

[83regalsx]

The overhaul manual calls for a JD lubricant on the o rings. It’s some slimy stuff. I can’t get to my bottle currently as I have everything covered for a project I’m painting. You going to repair the cracks or replace the head?

Also, the JD rings were far superior to any aftermarket options I found. The markings on the rings were an exact match for those removed. I didn’t think much of the aftermarket head gaskets either so went with Deere. Much better looking gasket although a bit more pricey.

Edit: There is no sealer on the o-rings, just a lubricant.

I will be ordering a new loaded head from Hoye tractor. I also went with a headgasket from JD, price wasnt that bad at $60 either. You think its worth the extra money for a set of JD piston rings as well? I just got my kit from Weaver and everything looks pretty good except I don't like the snap rings for the wrist pins as much as the OE clips and the oil ring didn't impress me that much. I was going to live with it though as it is just an in-frame on a high hour machine. If you wouldnt mind posting the part number on the bottle that would be great.

 

[83regalsx]

Re the liners. Yanmar used to recommend that the liners be put in with lube and no sealer. I'll have to go do some digging to if I have any notes on installing liners.

Looking at the pictures the liner that you pulled out has a lot of erosion. What do you think caused that?
rScotty

And thats how i was under the impression it should be done as well, i was thrown for a loop upon disassembly when i found the "goop" all over the top ring. Who knows, maybe it was due to the o-ring breaking down and getting mushy.

The liners are in very rough shape. I am guessing that perhaps this tractor ran with a cracked head for a long time and had corrosive combustion gasses in the coolant for quite some time. Assuming low quality coolant and lack of maintenance was an issue as well. When I purchased the machine it had been sitting for six months, previous owner knew it had an electrical problem and couldnt get it running but he was unaware of the engine problems when i told him.

 

[83regalsx]

Here’s where I stand now. I ordered The head from Hoye this morning along with a few other hoses and little bits. Going to get some John Deere lube possibly today. I have everything cleaned up and washed down. The o-ring grooves in the block look great. Going to swap the pistons into the old rods next and I should be good to go and just be waiting on the head to show up.

You can see some corrosion in the last picture but the backing side of the o-ring groove looks great so I’m not worried.

 

[jaydee325]

The corrosion/pitting pictured on the sleeve and block near the o-ring groove is caused by cavitation of the coolant. This is generally avoided by recommended coolant flush/change intervals.

Just google diesel engine coolant cavitation to learn more.

 

[rScotty]

The corrosion/pitting pictured on the sleeve and block near the o-ring groove is caused by cavitation of the coolant. This is generally avoided by recommended coolant flush/change intervals.

Just google diesel engine coolant cavitation to learn more.

That's where I was going with the original question. Cavitation rather than Corrosion. Or maybe both together.
Cavitation pitting has always been a problem with liners. They can ring like a bell.
Wonder if liners are available at a reasonable price?