D5H Overheating

JohnK · Jul 26, 2021

My D5H is still overheating. I've rebuilt the radiator, replaced the transmission oil cooler and flushed and replaced the antifreeze and it's still getting hot after about an hour of moderate work. Both temperature gauges for the water and oil are well over 200F. Then after I shut off the engine the overflow fro the radiator cap puts out antifreeze.
What's left to change? The water pump? I can't think of anything else.

Almost forgot... Serial # 8RC00990

Vetech63 · Jul 26, 2021

You need to know the temps on your radiator top vrs bottom. Also the oil cooler in and out differential. This will tell you if you have a air flow problem, plugged cooler or core, water pump issue, or there is a heating problem in the engine or transmission.
The air flow from the engine fan through your radiator core is what cools the engine system. Have you checked the fan belts, pulleys condition, and the fan blades? You should see a 30-40 degree drop in temp from the top of the radiator to the bottom outlet.

361brock · Jul 26, 2021

I had same problem with excavator. Would over heat after about an hour. Radiator, coolant flow, hoses and belts looked good. The twin matched set belts were sunk into the V to far and were slipping at high rpm. Grab hold of the fan, if you can turn the blade and the belt stays still, you found the issue.

JohnK · Jul 26, 2021

Yes. I rebuilt the radiator and had it tested at a radiator shop for heavy equipment. The transmission cooler is new and I checked it out before installing it. When I flushed everything, I didn't have any plugged areas that I could find. Fan blades are blowing air from the engine through the radiator, which I found odd, but I've heard that is not uncommon. Belts are good and the piping and hoses are all good from the radiator to the oil cooler and back again. I'll have to get an IR thermal checker to see what the temp differences are.

Is there a thermostat on this engine? I wasn't able to find anything online through Caterpillar. I can only assume there isn't one. Which is why I wondered if I am getting any flow from the water pump.

I can let it set for about 30 mins and the temperature drops quite a bit, so that makes me think that the radiator is somewhat working.

Tinkerer · Jul 26, 2021

Might be a water pump problem.

Bluox · Jul 26, 2021

JohnK said:
Yes. I rebuilt the radiator and had it tested at a radiator shop for heavy equipment. The transmission cooler is new and I checked it out before installing it. When I flushed everything, I didn't have any plugged areas that I could find. Fan blades are blowing air from the engine through the radiator, which I found odd, but I've heard that is not uncommon. Belts are good and the piping and hoses are all good from the radiator to the oil cooler and back again. I'll have to get an IR thermal checker to see what the temp differences are.

Is there a thermostat on this engine? I wasn't able to find anything online through Caterpillar. I can only assume there isn't one. Which is why I wondered if I am getting any flow from the water pump.

I can let it set for about 30 mins and the temperature drops quite a bit, so that makes me think that the radiator is somewhat working.

Cat calls them water temperature regulator ,where the top hose hooks to the engine remove the 4 bolts that hold the elbow to the engine head and there she is.
Bob

Nige · Jul 26, 2021

JohnK said:
I can let it set for about 30 mins and the temperature drops quite a bit, so that makes me think that the radiator is somewhat working.

Here's a suggestion. Next time the temp gets above 200 instead of shutting down the engine stop the tractor, shift into neutral and set the engine RPM about midway between Low & High Idle. How long does it take for the coolant temp to drop 10 degrees.?

JohnK said:
Fan blades are blowing air from the engine through the radiator, which I found odd, but I've heard that is not uncommon.

The fan is designed to blow air out of the front so it doesn't suck in dust coming off the blade. How about taking a photo of the fan.? There is a right way round for it to be installed and if it's the wrong way it will still blow air forwards but nowhere near as much as it should.

If you open up the temperature regulator housing make sure to note the Part Number of the regulator and the temperature it's suposed to open at. They will be marked on it.

Delmer · Jul 26, 2021

JohnK said:
I can let it set for about 30 mins and the temperature drops quite a bit, so that makes me think that the radiator is somewhat working.

It should drop to 180 or so much quicker than 30 minutes, and it should stay there. The thermostat will usually have a temperature stamped on it somewhere, test it in a pan of water on the stove and it should start to open at the temperature stamped on it, and it should be fully open at 200 or boiling. The belts can look fine but be worn, or the pulley can be worn rounded so the belts don't grip properly.

The infrared thermometer will probably tell you if the water is moving correctly or not. how much has it been worked since the radiator cleaning? and how dusty?

Coaldust · Jul 26, 2021

VeTech said it best. To recap, we can guess all day and keep throwing parts on it hoping for the best. Four simple temperatures measurements will provide the data needed to determine if the overheating issue is a flow problem or a capacity problem.

JohnK · Jul 26, 2021

Thanks everyone! I'll do some more checking in the morning and see what I find out. I'll get a picture of the fan also.

grandpa · Jul 27, 2021

Make double sure the fan is blowing air through the radiator and not around it. Im not familiar with a D5 model set up, but I have a 325 excavator that would heat up just driving it 200 yards. I resealed along both sides of the radiator and now I can dig all day in 100F temps and it only gets one mark above halfway. I would have never dreamt that that was that big of a deal.

Bluox · Jul 27, 2021

Vetech63 said:
You need to know the temps on your radiator top vrs bottom. Also the oil cooler in and out differential. This will tell you if you have a air flow problem, plugged cooler or core, water pump issue, or there is a heating problem in the engine or transmission.
The air flow from the engine fan through your radiator core is what cools the engine system. Have you checked the fan belts, pulleys condition, and the fan blades? You should see a 30-40 degree drop in temp from the top of the radiator to the bottom outlet.

Cat calls for 15 degree F max difference top to bottom radiator, max 40 degree F between top of rad and torque oil outlet.
Top of tank and ambient temp max 110 degrees F difference .

Delmer said:
It should drop to 180 or so much quicker than 30 minutes, and it should stay there. The thermostat will usually have a temperature stamped on it somewhere, test it in a pan of water on the stove and it should start to open at the temperature stamped on it, and it should be fully open at 200 or boiling. The belts can look fine but be worn, or the pulley can be worn rounded so the belts don't grip properly.

The infrared thermometer will probably tell you if the water is moving correctly or not. how much has it been worked since the radiator cleaning? and how dusty?

This motor uses a regulator and the hot water test is water at 195 degrees F for 10 minutes hanging in water and check opening 3/8 inch ,any less regulator is bad.

Nige said:
Here's a suggestion. Next time the temp gets above 200 instead of shutting down the engine stop the tractor, shift into neutral and set the engine RPM about midway between Low & High Idle. How long does it take for the coolant temp to drop 10 degrees.?
The fan is designed to blow air out of the front so it doesn't suck in dust coming off the blade. How about taking a photo of the fan.? There is a right way round for it to be installed and if it's the wrong way it will still blow air forwards but nowhere near as much as it should.

If you open up the temperature regulator housing make sure to note the Part Number of the regulator and the temperature it's suposed to open at. They will be marked on it.

This tractor only used a 195 F regulator and had a folded core rad originally.
Bob

Delmer · Jul 27, 2021

thank you for the specs. those temps have to be taken at the hottest engine temp you dare, at or near the thermostat temp won't tell you anything, as the thermostat will not be fully open.

Bluox · Jul 27, 2021

Delmer said:
thank you for the specs. those temps have to be taken at the hottest engine temp you dare, at or near the thermostat temp won't tell you anything, as the thermostat will not be fully open.

All testing is done at operating temperatures .
A Cat regulator is not a thermostat it is more of a temperature controlled flow control valve so that is the opening spec at the 195 temperature.
Bob

JohnK · Jul 27, 2021

361brock said:
I had same problem with excavator. Would over heat after about an hour. Radiator, coolant flow, hoses and belts looked good. The twin matched set belts were sunk into the V to far and were slipping at high rpm. Grab hold of the fan, if you can turn the blade and the belt stays still, you found the issue.

I grabbed the fan and the belts turned with the fan. It was slipping on the shaft below. I'll tighten the belts and see what happens. Thanks!

361brock · Jul 27, 2021

If the belts are sinking to deep into the V pulleys, you'll need to over tighten to stop the slip. New belts will ride higher and not need to be over tightened which would lead to bearing failure on your alternator or what ever else is driven by the belts.

JohnK · Jul 27, 2021

I tightened the belts and that seemed to help. My water temperature is around 210 or a little higher according to the gauge and the oil temp is (maybe) 10 degrees higher while I'm pushing dirt. I'm getting a IR thermometer to check the temps everywhere. I don't trust the gauges that I think is original to the machine. They're pretty hard to read through the stained glass.

Delmer · Jul 27, 2021

Bluox said:
All testing is done at operating temperatures .
A Cat regulator is not a thermostat it is more of a temperature controlled flow control valve so that is the opening spec at the 195 temperature.
Bob

Huh? what is the difference? if the engine is hot and then idles for hours at -20, the radiator is going to have some serious temperature drop. Are you saying the "thermostat" is fully open at 195 so that is hot enough to check the radiator temperature drop? that makes perfect sense.

All I know is, if the thermostat is closed, or partially open, then the temp drop won't tell you much.

Coaldust · Jul 27, 2021

What’s the difference between a T stat and a regulator? ? A lot. Some of which is terminology. Most people use the term thermostat to refer to a automotive style choke version. Which you don’t find in Cat engines except Perkapillars.

Cat uses blocking style water regulators and a bypass channel to route the coolant.

It even gets more confusing with some of the other brands where you may find the lesser used partial blocking regulators.

But, I’m a cooling system geek, having this stuff drilled into my head by Cat and their cool aid. But, it’s important stuff when commissioning a power plant or doing a sea trial. Gotta have your ducks in a row when telling a customer their new keel cooker is undersized or their radiator is too small for the ambient temp.

JohnK · Jul 27, 2021

Nige said:
Here's a suggestion. Next time the temp gets above 200 instead of shutting down the engine stop the tractor, shift into neutral and set the engine RPM about midway between Low & High Idle. How long does it take for the coolant temp to drop 10 degrees.?
The fan is designed to blow air out of the front so it doesn't suck in dust coming off the blade. How about taking a photo of the fan.? There is a right way round for it to be installed and if it's the wrong way it will still blow air forwards but nowhere near as much as it should.

If you open up the temperature regulator housing make sure to note the Part Number of the regulator and the temperature it's supposed to open at. They will be marked on it.

Here's the fan position

D5H Overheating

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