1978 John Deere 850 Project

[wct097]

Engine is open, pistons are out. This is what I've found.

#1 cylinder sleeve wall is cracked or corroded:

#1 piston looks decent but has a broken oil scraper ring and two of the three other rings are stuck. Shows some vertical wear, but not sure if that's an issue.

#2 cylinder sleeve looks OK visually, might be able to hone it

#2 piston is dirty, but has no visible wear. Oil scraper ring is broken.

#3 cylinder sleeve has several vertical wear marks. Not sure if it can be honed.

#3 piston shows very noticeable vertical wear marks.

Timing set looks good. A little crud on the cam gear. Coolant hose was full of some sort of crud.

Injection pump was a royal pain to get out. The throttle/governor connects to the pin sticking up at the bottom of the picture. That's connected to a bar that slides side to side. The governor is connected to the pin with a collar and cotter pin that is almost impossible to get to inside the engine. That's stuck on mine and the pin/bar was impacting the side of the case when I tried to pull it off. I had to take the timing cover off the engine to get something in there to tap it back to the center. So that's a problem, I'm sure... the spring that moves it isn't super powerful so I think that should move pretty easily. Likewise, the three rollers that ride on the camshaft are spring loaded. Note the middle one stuck in.

Next step is to take it to the machinist to have the #1 sleeve removed and the block
& head checked for cracks.

 

[GPintheMitten]

I hope you can make it work for you.

 

[jenkinsph]

I see where Deere wants $328 per cylinder for pistons rings and liner. I would check an engine parts supplier to see if you can get these parts cheaper. If so I would consider changing all three out. If I am going to rebuild an engine it would be better to renew all three at once.

 

[Ed of all trades]

I will be watching and wishing I had a project like that. Looks like fun to me. Hope the block is good. Ed

 

[R Barger]

I see where Deere wants $328 per cylinder for pistons rings and liner. I would check an engine parts supplier to see if you can get these parts cheaper. If so I would consider changing all three out. If I am going to rebuild an engine it would be better to renew all three at once.

Hoye tractor has them in the $250.00 range.

 

[wct097]

This is what I'm finding at Antique Tractors - Yesterday's Tractors : Parts and Online Community

Piston (CH10355): $79.13
Rings (CH12046): $27.96
Sleeve (CH13597): $118.21

Total: $225/cylinder for everything

Haven't called my local dealer, but they came in comparable with some other sites I've searched on other parts.

I have no idea what the machinist will say for cylinder 2 & 3 or for the pistons in general. I figure at minimum, I'm replacing sleeve #1, piston #3, and all three sets of rings. I lean towards replacing with new parts, but it really depends on the big picture. I'm not going to spend $3k refreshing the engine on this tractor. My upper limit is in the $1800 range.

I think this is right for some other misc items
Crank bearings (2x) CH10338 ~ $38/ea
Cam bearing CH14887 ~ $33
Rod bearings (3x) AM875927 ~ $22/ea
Rod bushing (3x) MIU801273 ~ $6/ea

I'm thinking parts wise, with gaskets and a new water pump, I'm looking at a minimum of ~ $550 up to about $1200. Don't have a price on the work or the injection pump rebuild yet. One of the two machinists I spoke with quoted me under $100 to inspect the block and head for cracks to determine if it's even capable of being rebuilt.

 

[wct097]

Got the fuel injection pump loosened up and partially disassembled. Tool the roller/pistons out and cleaned everything up. Have the pump body soaking in ATF overnight and expect I can get it back together and functional without an actual rebuild.

 

[2458n]

Well you do have a good deal of work ahead of you. Same tractor with loader came out of a barn in Tipp City Ohio in March. 5600 hours selling due to a divorce. 4800.00 bought it with a 10% buyers premium. Same man bought the tiller for 1200. So for 6600.00 he was down the road. When looking at Tractorhouse before the sale it seems like the tractor sold for 14000.00 new. Good luck with your project

 

[wct097]

Just an update here. Ended up doing a complete rebuild. New sleeves, pistons, rings, bearings, etc. I think my rebuild cost is about $2k with parts, machine work, new water pump, new muffler, fuel filter assembly, and inner combustion chambers. I cleaned, disassembled, and reassembled the injection pump. I think it will work but won't know until I can actually test it with fuel on the tractor. Two of the three injector nozzles were stuck. One took considerable effort to free up, but seems to be in working order now. The injectors were stuck fast in the head and the machinist had to beat them out from the inside which damaged the inner precombustion chambers. I've replaced those. Hope to button the engine up tonight and try to get it back on the tractor Friday, weather permitting.

Assuming I get it running, the tractor still needs some work, but I'll have a running tractor with basically a brand new engine for ~ $3k invested.

 

[wct097]

I got the engine back on the tractor on 7/9, but ended up fighting fuel system problems all day. Got it to run a couple times but ultimately pulled the fuel pump and took it to a localish diesel shop that rebuilds them. Diagnosis was that the pistons in the pump were severely worn. Rebuild cost was north of $700, so I ended up ordering a new pump from Hoye Tractor. Hopefully get it running next weekend.

So this tractor is really a shining example of a "basket case". Not only did I have to address engine internals, but also worn/damaged fuel system components, and found that the previous owner had possibly damaged the fuel pump check valves by removing them and reinstalling them incorrectly. I'm still expecting to need to replace hydraulic lines and it wouldn't surprise me to need seals replaced in the hydraulic cylinders. By the time I do that, and replace the rusted out seat, I'm probably going to be into the tractor for $4k, including the purchase price. Still not bad, but more than I'd hoped to spend. On a positive note, I've got basically a zero hour engine that will probably outlast me if I keep the fluids and filters changed. I also bought one of the exhaust flappers from Tractor Supply. I won't be letting any rain get in there. Learned that lesson from the PO's mistakes.

 

[pmsmechanic]

I've been following along on this one because I like these kind of projects.

I noticed there is a gear shift between your legs when you are sitting on the tractor. You need to check the rubber boot on those and make sure there are no cracks in it. What happens is the water runs down the lever and into the transmission if the boot is no good.

 

[wct097]

So I ended up replacing the fuel pump, which resolved the starting issues. Unfortunately that made me aware of another issue. Once started, the tractor wouldn't move. After some time diagnosing the issue, I determined that something must have been wrong with my re-assembly and figured it was related to the pressure plate or release bearing. Turns out that the clutch shaft & coupling had shifted forward during the seating of the engine and ended up not actually attached to the transmission input shaft. The result was that it was rubbing the input shaft and turning the transmission, but not enough to actually move the tractor....also it was turning the transmission in reverse.

I split it again today which is how I figured that out. We have it back together, but not fully bolted up because I need to replace the clutch linkage (broke during initial troubleshooting/adjustment). Without the clutch linkage in place, I can't get the release bearing to seat properly. Maybe next weekend.....

You can see where the coupler was spinning against the front of the transmission here:

I've been following along on this one because I like these kind of projects.

I noticed there is a gear shift between your legs when you are sitting on the tractor. You need to check the rubber boot on those and make sure there are no cracks in it. What happens is the water runs down the lever and into the transmission if the boot is no good.

I'll take a look next time I'm out. It's currently under cover, so less of an issue, but still should be addressed.

 

[wct097]

Tractor is running, moving, and the front end loader articulates. Still have a good bit of work to do before I'd say that it's in usable condition, but we're pretty close. I was very pleased to drive it around yesterday under its own power. Getting the FEL back on with two people was a quite the ordeal, especially since I didn't mark the hydraulic lines and really have no experience with hydraulics other than a basic understanding of how it works.

Unfortunately, I don't have any pics or videos to show because I didn't have time to really get any. Maybe next weekend when I get my steering rod end replaced and can actually work it a little.

I do have a handful of questions that I haven't been able to figure out on my own, mainly surrounding the hydraulics. My tractor has three levers on the right side of the seat. One clearly controls the 3-point, and I think is described in the manual as a "rockshaft control valve". The other two are for the front end loader and are described in the manual as a "selective control valve" or SCV. There is also a screw in/out valve between your legs if you're sitting in the seat. Not knowing how the hydraulics work or remembering how the lines were hooked up, I flailed around for a bit and managed to get the 3-point to lift using a combination of the lever and the screw in valve under the seat between my legs. Likewise, we managed to get the lift circuit to work with the right hand SCV and the bucket circuit to work with the left hand SCV. We did have to open and close the screw in valve a couple times to make things function. Now, with that explained, I'm not 100% sure which SCV lever is supposed to go with which circuit or if that even matters. Likewise, I'm not sure that I have them correctly aligned or if they're backwards. I think I have at least the lift circuit reversed.

This picture shows the original seat pan. On the right are the two SCVs and the 3-point lever:

I haven't actually tried lifting any weight in the bucket or on the 3-point yet. The bucket action seemed weak and I figured I have some adjustment or tweaking to do.

Can someone explain to me how the hydraulics on this tractor are supposed to work, what the function of the screw in (open/close) valve is and which lever should be connected to which circuit?

Also, I'm slightly confused by my fuel filter assembly. I purchased a new assembly that looks identical to this:

My assumption is that the C<-->O designation depicts the lever being in the (O) open position in this picture and that to close the valve, you'd flip the lever 180 degrees to the (C) closed position. What I've found is that with the lever in the 12 o'clock position, that fuel flows freely while in the 3 o'clock or 6 o'clock (pictured) position fuel doesn't flow or only dribbles out. Am I missing something here? I'm hoping that the 12 o'clock position isn't a bypass or something that flows unfiltered fuel.

My second question regarding the fuel filter has to do with bleeding. After we had the tractor running, having bled the lines again, I came close to running it out of fuel. The filter bowl was previously full and drained down to about 1/3 full before I noticed, shut off the tractor, and added fuel to the tank. Upon restarting and running a bit, the filter bowl never refilled. I'm assuming I should have bled that using the screws at the top of the filter housing. Is that correct?

 

[Rock knocker]

Tractor is running, moving, and the front end loader articulates. Still have a good bit of work to do before I'd say that it's in usable condition, but we're pretty close. I was very pleased to drive it around yesterday under its own power. Getting the FEL back on with two people was a quite the ordeal, especially since I didn't mark the hydraulic lines and really have no experience with hydraulics other than a basic understanding of how it works.

Unfortunately, I don't have any pics or videos to show because I didn't have time to really get any. Maybe next weekend when I get my steering rod end replaced and can actually work it a little.

I do have a handful of questions that I haven't been able to figure out on my own, mainly surrounding the hydraulics. My tractor has three levers on the right side of the seat. One clearly controls the 3-point, and I think is described in the manual as a "rockshaft control valve". The other two are for the front end loader and are described in the manual as a "selective control valve" or SCV. There is also a screw in/out valve between your legs if you're sitting in the seat. Not knowing how the hydraulics work or remembering how the lines were hooked up, I flailed around for a bit and managed to get the 3-point to lift using a combination of the lever and the screw in valve under the seat between my legs. Likewise, we managed to get the lift circuit to work with the right hand SCV and the bucket circuit to work with the left hand SCV. We did have to open and close the screw in valve a couple times to make things function. Now, with that explained, I'm not 100% sure which SCV lever is supposed to go with which circuit or if that even matters. Likewise, I'm not sure that I have them correctly aligned or if they're backwards. I think I have at least the lift circuit reversed.

This picture shows the original seat pan. On the right are the two SCVs and the 3-point lever:

I haven't actually tried lifting any weight in the bucket or on the 3-point yet. The bucket action seemed weak and I figured I have some adjustment or tweaking to do.

Can someone explain to me how the hydraulics on this tractor are supposed to work, what the function of the screw in (open/close) valve is and which lever should be connected to which circuit?

Also, I'm slightly confused by my fuel filter assembly. I purchased a new assembly that looks identical to this:

My assumption is that the C<-->O designation depicts the lever being in the (O) open position in this picture and that to close the valve, you'd flip the lever 180 degrees to the (C) closed position. What I've found is that with the lever in the 12 o'clock position, that fuel flows freely while in the 3 o'clock or 6 o'clock (pictured) position fuel doesn't flow or only dribbles out. Am I missing something here? I'm hoping that the 12 o'clock position isn't a bypass or something that flows unfiltered fuel.

My second question regarding the fuel filter has to do with bleeding. After we had the tractor running, having bled the lines again, I came close to running it out of fuel. The filter bowl was previously full and drained down to about 1/3 full before I noticed, shut off the tractor, and added fuel to the tank. Upon restarting and running a bit, the filter bowl never refilled. I'm assuming I should have bled that using the screws at the top of the filter housing. Is that correct?

1) You normally bleed the filter by one of the two screws on the upper housing. If you had air in the chamber after some use, then there is a leak, probably at the bowl ferrule, bleeder screws or inlet hose. It may not be enough to leak when the tractor is static and parked, but when a slight fuel vacuum occurs during operation then air could be sucked into the bowl.

2) Not sure exactly what your question is about the hydraulics, I'll read the book later and see if I can come up with a cogent answer.

 

[wct097]

1) You normally bleed the filter by one of the two screws on the upper housing. If you had air in the chamber after some use, then there is a leak, probably at the bowl ferrule, bleeder screws or inlet hose. It may not be enough to leak when the tractor is static and parked, but when a slight fuel vacuum occurs during operation then air could be sucked into the bowl.

I don't think it had air in the chamber until the fuel in the tank was exhausted. After refilling the tank, the air remained. I assume that is due to me not bleeding it after air (or vacuum) was introduced by the low fuel situation.

2) Not sure exactly what your question is about the hydraulics, I'll read the book later and see if I can come up with a cogent answer.

I'll see if I can narrow it down:

1. What is the function of the open/close hand screw between my legs when sitting in the seat?
2. Are the two selective control valves identical or is one dedicated to lifting the FEL and the other dedicated to the bucket?
3. Which direction should I pull/push the lever to lift the arms?
4. Which direction should I pull/push the lever to dump the bucket?

Thanks!

 

[Rock knocker]

I don't think it had air in the chamber until the fuel in the tank was exhausted. After refilling the tank, the air remained. I assume that is due to me not bleeding it after air (or vacuum) was introduced by the low fuel situation.

OK, I got lost in the chain of events



I'll see if I can narrow it down:

1. What is the function of the open/close hand screw between my legs when sitting in the seat?
Never ever used ours, it should be the control for the percentage of flow the rockshaft receives in relation to the SCV
2. Are the two selective control valves identical or is one dedicated to lifting the FEL and the other dedicated to the bucket?
One does have a float position for the loader boom. I did remove ours and replace with a aftermarket Prince valve on the loader itself in 1991
3. Which direction should I pull/push the lever to lift the arms?
Forward for both boom down and curl down (dump)
4. Which direction should I pull/push the lever to dump the bucket?
Forward

Thanks!

......

 

[Rock knocker]

1. What is the function of the open/close hand screw between my legs when sitting in the seat?

Seemed like an easy question, but I had to go thru my I&T and JD Technical manuals, as well as our owners manual to find the answer.

That valve is the rockshaft stop valve. It seems to be used to hold the rockshaft in a single position. It is also used in various positions during hydraulic diagnosis. Like I said, ours has never been used, and seems impossible to turn. Not wanting to create a proble where there is none, I haven't tried very hard.

 

[murphy1244]

Seemed like an easy question, but I had to go thru my I&T and JD Technical manuals, as well as our owners manual to find the answer.

That valve is the rockshaft stop valve. It seems to be used to hold the rockshaft in a single position. It is also used in various positions during hydraulic diagnosis. Like I said, ours has never been used, and seems impossible to turn. Not wanting to create a proble where there is none, I haven't tried very hard.

On my tractor that valve controls the rate of drop on the 3 point.

 

[Rock knocker]

John Deere 650-1050+ have a seperate valve to control the drop of the three point rock shaft

 

[jd110]

For normal operation, the knob between your legs should be fully counter clockwise. It regulates flow of oil into the rockshaft. The left scv lever should raise loader when pulled back and lower when pushed forward. There should be a detented position when pushed full forward to allow the loader to "float". the right scv lever should curl bucket back when pulling lever back and dump bucket when pushed forward.