850 Won't Start

[Republic of Texas]

Troubles begin:

I was out shredding 2 weeks ago when I let the radiator clog up with debris and the tractor over heated. Left it in the pasture for the night. Next morning I returned, filled it full of coolant and it fired right up. I drove it straight to the house, let it cool down, then proceeded to spray out the radiator with the water hose.

Once the radiator was nice and clean, I attempted to start the tractor. Clunk! Clunk! The starter engages but does not turn the flywheel. I inspect wiring and what-not, and find that the battery (had both top posts and side posts) made contact with the frame on both + and - posts. It was making a frying sound along with melting some plastic on the battery and a little smoke. Not good.

Mechanic buddy said it's the starter. I get a new starter and put it on with questionable battery. Same symptoms. Clunk! Clunk when I turn the key. My thinking was that the old starter is good, it's the battery that's bad. So, I return the new starter to Oreilly's and get a new battery instead. Put on the new battery, same thing: Clunk! Clunk!

Measured voltage to starter with key engaged, 8v. I read on here that the starter needs at least 9v to turn the motor. Short of rewiring the whole tractor, I added a start relay. Same Clunk Clunk.

I decide to jump the starter solenoid with a piece of wire (tired of climbing on/off tractor) so I can stand by the motor and look/listen better. Same clunk naturally. I keep touching the wire to the starter (pissed off) and the motor turns over for a second!!! Great! Hit the wire to the starter again, clunk! Except this time, fuel spits out from around the injector closest to the motor....... no clue here.

As I am rethinking my situation, I notice the compression adjuster on the top of the motor and so I pull it back to lessen the compression. Motor spins over!! But now, fuel spits out of the smoke stack! I put the compression adjustment back where it should be. Fuel spits out around the injector again.

I'm at my wit's end. At this point it's probably something extremely simple but I can't think of it (not a diesel mechanic). Is it the starter?

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I can add pictures or videos if someone thinks it will help diagnose the problem.

 

[beenthere]

:welcome: to the forum.
Doesn't sound good, but hopefully there will be a simple and happy ending (as you suggest).

Sounds like the trouble started when you sprayed it down with water to clean, as the tractor started in the field after adding coolant.
Then too, maybe something other than debris in the radiator caused it to overheat...head gasket? piston? ??

 

[Republic of Texas]

How can I verify that a head gasket or piston is bad without dismantling the motor?

 

[Republic of Texas]

Can anyone add anything? I have no one to ask who won't charge me $65+ an hour. Can someone please help?

 

[beenthere]

You mentioned a "mechanic buddy". Does he charge $65?

If working on it yourself, then getting a copy of the tech (service) manual would be first priority, IMO.

But things may be serious enough, that bucking up to hiring it done may be in order here.

Can you tell us more about your situation? Experience yourself, as well as more history of this tractor. Tools you have available, and anything else that will give us an idea how to give you direction.

 

[AGGIE00]

That little yanmar is about as simple as it gets. Had the same thing happen to my dad's many years ago and replaced the head gasket. It only takes an hour or so to replace.

 

[Republic of Texas]

Ok, so if I'm understanding correctly, it is in fact water/coolant leaking inside the head. This is most likely due to overheating wearing down the head gasket? Perhaps age as well...?

I will order a head gasket and go from there. I will post back when I replace the head gasket. I really appreciate the advice!!

Note* - Mechanic buddy doesn't charge me, but he's not 100% certain what it is and we both ran out of ideas. I can do the work, but diagnosing problems isn't my specialty.

 

[Republic of Texas]

I appreciate the replies. I will be working on the tractor this weekend. Will post pictures and/or video. Again, I can't thank y'all enough!!!

 

[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.

 

[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.

 

[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.

 

[AGGIE00]

That little engine will take more abuse than most can dish out. Definitely check the head for cracks and warp, but from my experience a head gasket is all you will need. While it is off check the water pump and replace the thermostat. Ask Deere for the torque specs and pattern. It's pretty simple with a torque wrench.

The compression release is a slide rail on top of the head that holds the exhaust valves open. This is used for cold starting so the engine can be spun freely and started by simply disengaging the realease while it is spinning.

 

[Mechanos]

Yes... I sure would. I think I'd even pony up to have it magnafluxed.

 

[eastshores]

Joined just to share my recent experience since this thread was helpful. I have a John Deere 850 that was running fine.. I don't run it too often but ran it the day before and then came out and it wouldn't turn over.. didn't really do anything. I figured OK apparently the alternator isn't charging the battery and hooked up a charger. Next day with battery at 100% the same thing.

This set forth a series of tests. I first checked the cable connections to the battery. They were basically fine.. I had recently put a new battery on it and used dialectic grease so there wasn't any corrosion. Tightened just in case and still nothing. I thought ok maybe a safety switch.. so I wiggled all the levels and rocked it back and forth etc. with nothing. That's when I decided maybe the ignition switch went bad. I pulled the switch out, and it's a little confusing. If anyone else comes across this.. there are two wires that you should concern yourself with.. the thick white wire is a hot wire that comes off the starter to the ignition switch. There's a black wire with a white strip, that returns to the solenoid on the starter and this is where you want to check that when you turn the switch, that you register 12v. In my case it was fine and therefore I ruled out the safety switches as well as the ignition switch.

So my mind thought.. OK .. my solenoid has gone out since it wouldn't even click. I pulled the starter and took it down to Autozone. They were able to hook it up to their test machine and it fired right up. This was a big help because that isolated the issue to having a bad ground as some of the posters on here had advised. I bought a new ground cable and headed home. Installed the starter. Replaced the ground cable and when I was loosening the bolt in the frame for the ground cable I noticed it was basically stripped. It was tight.. but the threads were mashed flat. I found another bolt laying around and grabbed a nut and was able to secure the cable using the bolt with the nut to lock it down. Turned the key and she fired right up!

Thanks to all of the posters before me, it helped a lot. My father passed away last year and although he tought me a lot it is always nice to hear the voice of experience when mine is no longer here.