Deere 950 drinking coolant

   / Deere 950 drinking coolant #12  
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I have a 30 horse JD 950 from the late 80s. I'm noticing that this summer (after the usual winter storage) it is consuming coolant every time I run it - which is maybe 4 times.. Before brush hogging, I fill the reservoir to full, when I get back from 2-3 hours of work, the reservoir is still full but then the next day after it cools off, the coolant is at the low mark in the reservoir.

I don't see any signs of a leak and there is no white in the exhaust. I know that temp light bulb works - but that has not illuminated while working. Any thoughts?
My understanding of the way the reservoir works is hot coolant expanding flows from the radiator to the reservoir, which acts as a storage tank. Then as the coolant cools (contracts), radiator vacuum pulls water from the reservoir back into the radiator. By your filling the reservoir when it's cold, as hot coolant comes from the radiator to the reservoir, the reservoir then overflows onto the ground.
The reservoir should be low when cold, and the radiator should be about 1" from full when cold. You don't want to remove the cap when the radiator is hot, as the coolant is under pressure at that time and will blow out all over anything nearby (like you).
Start checking the radiator when cool, and advise. Don't pay any attention to the reservoir.
 
   / Deere 950 drinking coolant #13  

jaxs

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My understanding of the way the reservoir works is hot coolant expanding flows from the radiator to the reservoir, which acts as a storage tank. Then as the coolant cools (contracts), radiator vacuum pulls water from the reservoir back into the radiator. By your filling the reservoir when it's cold, as hot coolant comes from the radiator to the reservoir, the reservoir then overflows onto the ground.
The reservoir should be low when cold, and the radiator should be about 1" from full when cold. You don't want to remove the cap when the radiator is hot, as the coolant is under pressure at that time and will blow out all over anything nearby (like you).
Start checking the radiator when cool, and advise. Don't pay any attention to the reservoir.
Where did you come by "this understanding" owner/operator's manual or some other source?
The way I interpret owner's manuals is cold radiator should be full of coolant without any air and reservoir should have coolant to cold mark. Idea of coolant recovery being to keep system free of air bubbles. As most have said,engine cooling isn't something one should be guessing at.
 
   / Deere 950 drinking coolant #14  

Carl_NH

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01 Kubota B21TLB, 2010 Ferris 52" ZTR, Cub Cadet 1811, Gravely Super8
The OP wrote "Before brush hogging, I fill the reservoir to full, when I get back from 2-3 hours of work, the reservoir is still full but then the next day after it cools off, the coolant is at the low mark in the reservoir."

The issue is the reservoir should be at the "low mark" when cold, and at the Hot mark/full when hot, so by filling it up when cold, there is no room in the reservoir tank when hot, thus it overflows.

Still something doesn't sound right as this much variation in level is a concern -- I would want to know the actual temp running/hot as it could be overheating (Thermostat etc) and boiling off the antifreeze.
 
   / Deere 950 drinking coolant #15  

rScotty

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Kubota M59, JD530, JD310SG. Restoring Yanmar YM165D
My understanding of the way the reservoir works is hot coolant expanding flows from the radiator to the reservoir, which acts as a storage tank. Then as the coolant cools (contracts), radiator vacuum pulls water from the reservoir back into the radiator. By your filling the reservoir when it's cold, as hot coolant comes from the radiator to the reservoir, the reservoir then overflows onto the ground.
The reservoir should be low when cold, and the radiator should be about 1" from full when cold. You don't want to remove the cap when the radiator is hot, as the coolant is under pressure at that time and will blow out all over anything nearby (like you).
Start checking the radiator when cool, and advise. Don't pay any attention to the reservoir.

So if "Have tractor will travel" is correct, then the system is operating as intended.
I like his explanation. It covers all of the OP's original facts, then gives a logical explanation for what is happening, and means that the system is operating as intended. It working that way does depend on the reservoir having an airtight pickup tube that extends down somewhere to or below the bottom half of the reservoir. But most have that.

If it has that tube, I can't resist adding a little more detail to expand "Have Tractor's good advice.

After running the tractor and you shut it off and everything starts to cool down, the fluid in that reservoir will be drawn back into the radiator until one of two things happen.
1. the radiator will suck back fluid until it's radiator vacuum is equal to the air pressure, or .....
2. the radiator will suck back fluid until the fluid level in the reservoir falls below inlet to the pickup tube in the reservoir.

Either one of those things happening will stop the flow back into the radiator. And both are basically good. So when everything is cooled off the next morning make a mark on the reservoir at what ever level that fluid is at, and also take off the radiator cap to check that the fluid in the radiator is at the proper level (about an inch or so down from the cap).
If it is right in the radiator, put the cap on & don't add any more fluid to that reservoir. If it isn't high enough in the radiator or you are uncertain... it won't hurt to add fluid to the radiator.. but NOT to the reservoir. If you had to add fluid to the radiator, expect it may overflow while working but hang in there..... the fluid in the reservoir will go ahead and level itself out by a day later.

After reading through all this anyone can ask questions if they want. But to me it is sounding like the OP's JD950 is working right. I'd say it sounds like it has been getting rid of the unneeded extra coolant and then coming back to proper level the next morning.
And thanks to "Have Tractor will Travel" for his insight.

rScotty
 
   / Deere 950 drinking coolant
  • Thread Starter
#16  
OP
H

hondo964

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40
Tractor
JD 950
So if "Have tractor will travel" is correct, then the system is operating as intended.
I like his explanation. It covers all of the OP's original facts, then gives a logical explanation for what is happening, and means that the system is operating as intended. It working that way does depend on the reservoir having an airtight pickup tube that extends down somewhere to or below the bottom half of the reservoir. But most have that.

If it has that tube, I can't resist adding a little more detail to expand "Have Tractor's good advice.

After running the tractor and you shut it off and everything starts to cool down, the fluid in that reservoir will be drawn back into the radiator until one of two things happen.
1. the radiator will suck back fluid until it's radiator vacuum is equal to the air pressure, or .....
2. the radiator will suck back fluid until the fluid level in the reservoir falls below inlet to the pickup tube in the reservoir.

Either one of those things happening will stop the flow back into the radiator. And both are basically good. So when everything is cooled off the next morning make a mark on the reservoir at what ever level that fluid is at, and also take off the radiator cap to check that the fluid in the radiator is at the proper level (about an inch or so down from the cap).
If it is right in the radiator, put the cap on & don't add any more fluid to that reservoir. If it isn't high enough in the radiator or you are uncertain... it won't hurt to add fluid to the radiator.. but NOT to the reservoir. If you had to add fluid to the radiator, expect it may overflow while working but hang in there..... the fluid in the reservoir will go ahead and level itself out by a day later.

After reading through all this anyone can ask questions if they want. But to me it is sounding like the OP's JD950 is working right. I'd say it sounds like it has been getting rid of the unneeded extra coolant and then coming back to proper level the next morning.
And thanks to "Have Tractor will Travel" for his insight.

rScotty
Guys, thanks SO much for your thoughts. Here's a little more info:
The reserve tank is marked low and high. There is no hot and cold mark like the newer tractors. The manual say daily before start up, check engine oil etc etc. Check coolant level in recovery tank. if engine is cool and level is below "low" mark, add coolant to recovery tank to bring level to 'full' mark. So I have always checked fluids before I use the tractor (my dad beat that into my head) and this year after winter storage, I noticed that the fluid was below 'low' in recovery tank as I mentioned in the original post. I will say that the last time I used the tractor this week, the fluid did come down but it stayed just above "low" this time as opposed to dropping below "low" the previous 2-3 times.

Exhaust is clean, oil level is where it's been at since last fall when it was changed. (If there was a head gasket problem or a cracked block would the oil level increase from coolant getting in??) For the first time, I opened the radiator cap and the level is right at the top. Coolant looks pure.

Now the confession....I have had the tractor 14 years, only put 300+ hours on it, but never flushed the radiator OR changed the thermostat (which the manual says to do every 2 years).

What's the advice for the next step? I'm thinking get a new thermostat and a new radiator cap and see what happens. I should also check the air filter to see what that looks like.
 
   / Deere 950 drinking coolant #17  

rScotty

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Kubota M59, JD530, JD310SG. Restoring Yanmar YM165D
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.
 
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   / Deere 950 drinking coolant
  • Thread Starter
#18  
OP
H

hondo964

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Joined
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Messages
40
Tractor
JD 950
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.
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.
 
   / Deere 950 drinking coolant #19  

dodge man

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I have a newer JD and the coolant reservoir does the same thing. It ends up with just a little bit in the bottom when it’s cold. If I put anymore in it just gets puked out at some point when it gets hot, no real sign of it.
 
   / Deere 950 drinking coolant #20  

Carl_NH

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Hondo,

Yes you can use the infrared thermometer when cold on the pipe above the thermostat, then as engine warms up you should see the temp spike as it opens. Alternating between the block and the hose to check temp would be good too.

The excess coolant is overflowing out the top of the reservoir tank when in the field.
 
 
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