Deere 950 drinking coolant

[Tinhack]

IR thermometers aren't very accurate unless they are calibrated to the object emissivity. Read the instructions for it. If the emissivity can't be calibrated/adjusted, the temperature is probably wrong.

Also, the leak could be from the radiator cap. Most have a pressure relief spring under it and the radiator will have an overflow tube coming from the radiator neck. Take the cap off when it cool. Check the level of the radiator. If it's down, and it has a relief cap, the cap is probably bad. If it has a newer system which includes the expansion tank only, the pressure relief cap and overflow tube will be at the expansion tank. Those go bad too but, in both cases, the caps must be on tight.

For sure, your tractor is either eating coolant (blown head gasket) or it's leaking out.

 

[rScotty]

rScotty,

Thanks! I have been thinking alot about what you have said and your thoughts sound right to me. I will take the tractor out to brush hog in the next couple days (without filling the reservoir back up to full - since it is above low) and let you know how things go.

2 Questions:
I'm a little shy about testing the thermastat and I"m wondering if there is another way. Do you think an infrared thermometer would be fairly accurate (shooting say at one of the hoses)?.

Question: where would the excess coolant I've been putting in be going? Is it leaking out somewhere in the field while the tractor is running?

I have to say that this little Yanmar engine is great.

Question 1 :
I doubt the infrared thermometer is going to tell you much or anything about the coolant temperature in the engine. That isn't a guess. A few years ago I bought several IR guns - including expensive ones that compensate for emissivity - and tested them on our JD310SG (expensive machine) hoses and radiator and engine because it kept throwing a code that translates to a cooling problem. I sure didn't want to buy a new 100 hp JD engine...
The IR guns never did match what the gauge was showing - in fact none of them came close. Since it was winter, I tried them on my wood stove just to see that they worked.... and sent them all back.

Next I bought a box of small bi-metallic gauge type candy thermometers and mounted them against the water hoses with straps, insulation to isolate them from outside air, and wrapped them with flexwrap until just the dials showed. That seemed more accurate than the IR gun, but still didn't come within 25 degrees of what the dash gauge was showing for temperature.
So I took the thermostat out (not easy on a 310) and tested it. Perfect.....

The problem turned out to be a faulty 20 pin connector on the engine computer.... $3000, to fix it. It's all posted here on TBN

Question 2:
Going out on the ground is my guess. It wouldn't hurt to tape a plastic bottle if there is an overflow on the reservoir - not the radiator overflow.... you have to use the reservoir overflow if it has one and it must have something..
Then when cold you test it by filling the reservoir up to the "FULL" mark just like you used to do and see if it overflows that much when you are using it. That would be an absolute "proof of principle" type test.

Good luck,
rScotty

 

[hondo964]

Yes, it's easy to see that the problem is probably one of translation. They almost got it right. Where they say if the level is below "Low"mark when cold, they should have then said to add coolant to bring the level to the "Low" mark, not the "Full" mark. That's not surprising, I was around Yanmar and JD tractors and Yanmar service school a lot back then and we constantly had to correct their specs and shop manuals. So just make that change to your manual and it will be fine. And some owner down the road 30 years from now will thank you.

After all, the JD950 is a Japanese tractor, very similar to the ones that Yanmar made and marketed in the USA during the 1970s. We know them pretty well.

I wouldn't change a thing. Why would you? Sounds like yours is fine. I go that long between servicing mine too.
A new thermostat and a new radiator cap won't hurt anything if you just want to.... but it is going to be hard today to match the quality of the original parts on that tractor.

To check a thermostat, take it out of the tractor and put it in a pan of water completely submerged. Slowly heat the water on the stove and watch to see the thermostat open. There is a wax-filled steel bulb that will compress the spring that holds the thermostat shut. Use a candy thermomether to check that it is opening at the proper temperature. Use a candy thermometer for the proper range - $5.00 at the hardware store. Try not to let the water boil.

I forget the exact temperature it's in my service school notes somewhere. I'll post if I find it.
But the thermostat will begin opening somewhere in the 185 to 190 degree range (SEE EDIT BELOW(F) and be around 190 and should be fully open somewhere between 190 and 200 F. TRY NOT TOLET IT BOIL....and be sure to keep it completely submerged. although if you do mess up, the thermostat will probably be OK. Just check it again.

EDIT NEXT DAY: I found one reference in Yanmar's Service notes that when tested in hot water the thermostat should start to move open above 160F... Frankly I've never seen them move that low, but that's what they say. So maybe they do. Thermostat opening is progressive with temperature.

rScotty

BTW, all of those old ethylene glycol cooling systems work best with 50/50 ethylene glycol to water.

PROBLEM SHOULD BE SOLVED!
Eventually there was an evident drop of coolant by the drain plug. It turns out that there was a very small crack in the small hose that runs from the bottom of the radiator to the drain plug. the crack was on the backside so it could not be seen. But once I moved the little hose around with my fingers the coolant started flowing out.

Thanks for the guidance. Please look for a new thread with a question about solutions for cleaning radiators.

 

[rScotty]

PROBLEM SHOULD BE SOLVED!
Eventually there was an evident drop of coolant by the drain plug. It turns out that there was a very small crack in the small hose that runs from the bottom of the radiator to the drain plug. the crack was on the backside so it could not be seen. But once I moved the little hose around with my fingers the coolant started flowing out.

Thanks for the guidance. Please look for a new thread with a question about solutions for cleaning radiators.

Well how about that?

It turns out that in spite of all the thought on the problem, solving the problem was just a not-so-simple leak.

Thanks for the follow up.