JD 2640 overheating

I've got a JD 2640. The temperature gauge is going to red after it runs for a few minutes. The air cleaner restriction indicator is also on.
When I run it for a few minutes and the temperature gauge is getting to red, then I shut the tractor off, the radiator fins are not very warm at all. When I open the radiator cap and touch the coolant, it is warmer than when the tractor has not been run, but it's not hot.

I've put in new primary and secondary air filters. I put in a new thermostat. I also drained the coolant (opened the drain cock on the radiator and let coolant flow out), ran the engine for a few minutes while running water from a hose through the radiator, and refilled with a 50/50 mix. When I refilled, it only accepted 2 gallons, but capacity is supposed to be around 13 quarts.

What should I do next? Is there a way to tell if it is the water pump or if it is blockage in the radiator? Does the air cleaner restriction indicator offer a clue - or is there something else problematic with it? Is there any need to bleed air from the system - if yes, how?

Just hoping to learn from other people's experience. Thanks.

When you find the temperature gauge indicating over heating, touch the bottom radiator hose lightly to see if its hot. Your radiator tubes may be plugged blocking circulation or the water pump may have worn impellers. Hal
PS: Your temp gauge may need replacing.

I'll suggest to check rad & block with a laser thermometer or check temp with a manual temp gauge. When you replaced both air filters did you reset the air filter indicator?

(quoted from post at 15:13:37 10/17/14) I've got a JD 2640. The temperature gauge is going to red after it runs for a few minutes. The air cleaner restriction indicator is also on.
When I run it for a few minutes and the temperature gauge is getting to red, then I shut the tractor off, the radiator fins are not very warm at all. When I open the radiator cap and touch the coolant, it is warmer than when the tractor has not been run, but it's not hot.

I've put in new primary and secondary air filters. I put in a new thermostat. I also drained the coolant (opened the drain cock on the radiator and let coolant flow out), ran the engine for a few minutes while running water from a hose through the radiator, and refilled with a 50/50 mix. When I refilled, it only accepted 2 gallons, but capacity is supposed to be around 13 quarts.

What should I do next? Is there a way to tell if it is the water pump or if it is blockage in the radiator? Does the air cleaner restriction indicator offer a clue - or is there something else problematic with it? Is there any need to bleed air from the system - if yes, how?

Just hoping to learn from other people's experience. Thanks.

Click to expand...

When the temperature gauge says boiling hot and the engine feels lukewarm. It's time to replace the sender, gauge or both.
Check the fan belt, water pump pulley and alternator pulley if they are worn. Super tightening to prevent slip will ruin the water pump bearing and alternator bearing.

I am thinking the air filter restriction indicator is a dash light? (Sorry 2640 was not marketed here, 3140 here is similar) By looking at the parts catalog the later 2640 had this set up. If the temp gauge and the air filter light come on at the same time I would have a look at the wiring harness.

Since your trouble shooting is telling you that it is not really hot, you would probably do better at attacking the readout problem as opposed to an apparent non-existant overheat problem.

Thanks for the responses! While I was waiting for responses, I decided to take out the thermostat that I had just put it and try running without it. That worked. So either I installed the new thermostat incorrectly, or it does not work properly. I guess it could also (still) be a temp gauge / wiring harness problem - but it seems strange to me that the gauge was going up the longer the engine runs, and still goes up to mid-green when running without the thermostat.

I also check airflow from intake, through filter, past sensor, and on through hose - all seems ok. Guessing sensor (or wiring harness) bad there, too.

Running ok for now, so figuring this out will be a winter project when I get my fall chores done.

(quoted from post at 12:13:37 10/17/14) I've got a JD 2640. The temperature gauge is going to red after it runs for a few minutes. The air cleaner restriction indicator is also on.
When I run it for a few minutes and the temperature gauge is getting to red, then I shut the tractor off, the radiator fins are not very warm at all. When I open the radiator cap and touch the coolant, it is warmer than when the tractor has not been run, but it's not hot.

I've put in new primary and secondary air filters. I put in a new thermostat. I also drained the coolant (opened the drain cock on the radiator and let coolant flow out), ran the engine for a few minutes while running water from a hose through the radiator, and refilled with a 50/50 mix. When I refilled, it only accepted 2 gallons, but capacity is supposed to be around 13 quarts.

What should I do next? Is there a way to tell if it is the water pump or if it is blockage in the radiator? Does the air cleaner restriction indicator offer a clue - or is there something else problematic with it? Is there any need to bleed air from the system - if yes, how?

Just hoping to learn from other people's experience. Thanks.

Click to expand...

(quoted from post at 17:50:47 10/17/14) I am thinking the air filter restriction indicator is a dash light?

Click to expand...

You're correct. Late model 2640 has air cleaner light on dash but early model has the re-settable sensor under hood. According to OP he has later model tractor with dash light.

There is something more going on here. Removing the stat is treating a symptom but not solving the problem.
It could be that the water pump has failed and now the engine is thermocycling via gravity without the stat's restriction.
I assume you are familiar with how a diesel engine can be messed up operating too cold without a stat?
Unless you test the temperature sensor an gauge we are still guessing if there is a problem or not.
Having a machine that indicates too hot but still has a cool rad is a huge flag that something is still wrong.
I'll guarantee that if you unbolt the rad and remove it. The core with be 1/2 plugged with oily mud even after the best efforts to hose it out from the sides.

Ok. I'm coming back to this... tractor has been parked since early October.

I put a new thermostat in (tested old one, it was ok, but put new one in any way since I had it). Then I took the radiator off, and took it to have it boiled. They said the inside was very clean and it should be fine, outside was a little dirty. Put the radiator back on. Tractor still got into red zone after running for 15-20 minutes with no load.

Today I pressure tested the cooling system using a gauge that goes on the radiator in place of the rad cap. I pumped up to 17 psi, and it held there for more than 20 minutes. That seemed like a good sign regarding internal leaking.

But when I looked at oil level, it was high and the oil on the dipstick was milky. I took the dipstick with engine oil on it and held a flame to it - and heard crackling, which suggests to me that there is water in the oil.

So now I'm thinking that coolant is leaking when the engine gets hot, and that is why the radiator pressure test didn't show a leak.

That means there is a leaking head gasket, cracked/warped cylinder or head, or something of that nature - right? If so, I'm going to deem this over my head and find a pro. Before I do that - is there anything else that I should try? I guess I could change the oil and double-check that the oil level goes up - is it worth it? Maybe with today's warm temperatures after recent cold there was some internal condensation, as there was quite a bit of condensation on the exterior metal parts of the tractor. (It's been quite cold until the last couple of days - today is warm and humid, and there was condensation on many parts of the tractor.)

(quoted from post at 03:31:17 10/18/14)
There is something more going on here. Removing the stat is treating a symptom but not solving the problem.
It could be that the water pump has failed and now the engine is thermocycling via gravity without the stat's restriction.
I assume you are familiar with how a diesel engine can be messed up operating too cold without a stat?
Unless you test the temperature sensor an gauge we are still guessing if there is a problem or not.
Having a machine that indicates too hot but still has a cool rad is a huge flag that something is still wrong.
I'll guarantee that if you unbolt the rad and remove it. The core with be 1/2 plugged with oily mud even after the best efforts to hose it out from the sides.

Click to expand...

Water in oil could be caused from a electrolysis hole a one or more cylinder liners

Your diagnosis sounds correct to me. Likely a blown head gasket.

What happens is the compression gasses leak into the water jacket, displacing the coolant and causing a hot spot in the head, which begins to boil. The expanding steam pushes more coolant away from the head area, causing even more overheating. At the same time the overheated head warps and lifts up, allowing coolant to flow under the head from the coolant passages to the combustion chamber and the oil drain back and pushrod passages.

Changing the oil won't solve anything. (Though it will need to be changed once the problem is resolved.) The raised level and milky oil are more than just condensation. The overheating is more evidence of a more serious problem.

From your diagnosis, sounds like you have a good bit of engine knowledge. You could probably do this job, especially if you had a shop manual. Main thing is to get 'er done ASAP! The coolant sitting in the engine is not good.