1972 CAT D4D overheating

[Greenfielrider]

I really hope someone can help me and point me in the right direction:

I recently acquired a 1972 Cat D4D dozer, which I believe has a power shift. I was told that it had sat for 4 years in the field. Unfortunately, once I started working with it, it began to overheat severely. I'm not referring to any strenuous activity; this happens simply when driving in, for example, second or any other gear.

Now, the strange thing is that at idle or high idle, I can let it run for an hour or longer. It does slowly climb above the thermostat opening temperature (taking 45-60 minutes), and then the temperature basically stabilizes there. I didn't manage to overheat it when just high idling. I let it run for almost 2 hours with no issues.

However, once I drive it, it takes less than 10 minutes before it reaches the red zone on the temperature gauge. After a cold start, I may get about 20-30 minutes or so.

I checked the thermometer; it seems accurate. The red zone starts at around 210°F-215°F.

I also measured the entire system from top to bottom. Here are the readings from the infrared thermometer at operating temperature (regulator/thermostat open):
- Thermostat housing: 180°F
- Radiator inlet: 178°F
- Radiator outlet: 143°F
—> The radiator seems to be fine.
- Pump top/outlet: 180°F
- Pump bottom: 142°F
- Oil cooler in: 180°F
- Oil cooler out: 193°F
- Transmission oil in (not driven): 184°F
- Transmission oil out: 195°F

I also measured the pump pressure:
- Pump pressure cold: around 15psi
- Pump pressure warm: less than 10psi

Unfortunately, I only had a pressure gauge from a compression tester. It's hard to tell if it's 9psi or 5psi for the pressure when warm (180°F), but it drops significantly compared to when the thermostat is closed.

The thermostat is new.
A block test was negative (blue).
There are no bubbles in the radiator.
There is no oil in the coolant and no water in the oil.
No external coolant leaks.

Does anyone have an idea of what I could look for next or what could be causing this?

 

[Jim.ME]

I really hope someone can help me and point me in the right direction:

I recently acquired a 1972 Cat D4D dozer, which I believe has a power shift. I was told that it had sat for 4 years in the field. Unfortunately, once I started working with it, it began to overheat severely. I'm not referring to any strenuous activity; this happens simply when driving in, for example, second or any other gear.

Now, the strange thing is that at idle or high idle, I can let it run for an hour or longer. It does slowly climb above the thermostat opening temperature (taking 45-60 minutes), and then the temperature basically stabilizes there. I didn't manage to overheat it when just high idling. I let it run for almost 2 hours with no issues.

However, once I drive it, it takes less than 10 minutes before it reaches the red zone on the temperature gauge. After a cold start, I may get about 20-30 minutes or so.

I checked the thermometer; it seems accurate. The red zone starts at around 210°F-215°F.

I also measured the entire system from top to bottom. Here are the readings from the infrared thermometer at operating temperature (regulator/thermostat open):
- Thermostat housing: 180°F
- Radiator inlet: 178°F
- Radiator outlet: 143°F
—> The radiator seems to be fine.
- Pump top/outlet: 180°F
- Pump bottom: 142°F
- Oil cooler in: 180°F
- Oil cooler out: 193°F
- Transmission oil in (not driven): 184°F
- Transmission oil out: 195°F

I also measured the pump pressure:
- Pump pressure cold: around 15psi
- Pump pressure warm: less than 10psi

Unfortunately, I only had a pressure gauge from a compression tester. It's hard to tell if it's 9psi or 5psi for the pressure when warm (180°F), but it drops significantly compared to when the thermostat is closed.

The thermostat is new.
A block test was negative (blue).
There are no bubbles in the radiator.
There is no oil in the coolant and no water in the oil.
No external coolant leaks.

Does anyone have an idea of what I could look for next or what could be causing this?

Welcome to the forums.

I don't see a reading that you have posted that, to me, says it is overheating. It is possible the gauge/sensor has lost calibration.

Find where the temperature sensor is located on the engine (I would look around the top rear of the head) and check the temperature of the head right where the sensor is.

What temperature thermostat did you install?

 

[Greenfielrider]

Thank you for you super quick response

I tested the sensor/gauge. In this case -unfortunately- both are accurate and do work. The coolant is indeed getting too hot.
I installed a thermostat from Napa, 170F. I also tested it before I installed it.

 

[Fixingfarmer]

190-215 is fine 230 degrees be worried.

 

[Fixingfarmer]

Are you on any sort of slope? Tank is all the way full of coolant not relying on a sight gauge seeing coolant just under the cap? And is it venting out when overheating condition exists?

 

[Greenfielrider]

190-215 is fine 230 degrees be worried.

Its getting close to 240 (measured with an infrared thermometer) and deep in the red zone of the gauge. I usually turn off the engine as soon as its around 230. Today, for a brief moment I didn't pay enough attention to the temperature gauge and got it to almost 240F. And again, with just driving and a little bit of pushing snow.

 

[Greenfielrider]

Are you on any sort of slope? Tank is all the way full of coolant not relying on a sight gauge seeing coolant just under the cap? And is it venting out when overheating condition exists?

No slope. The radiator (no overflow tank) is fullI. It does vent a bit when its overheating but only a little bit. Most likely from overfilling the radiator. If I fill it up as described in the shop manual (0.5" below the cap), I believe it doesn't vent.

 

[Nordic]

My first suspect, given all the info you have, that your radiator needs flushing, possibly even the block may have more crud than comfort would permit. I never had a 3304, naturally aspirated, ever overheat. My 3304 Turbo would start climbing only if over 85 - 90 F outside summer temp. and that's really working the machine hard.

 

[Greenfielrider]

My first suspect, given all the info you have, that your radiator needs flushing, possibly even the block may have more crud than comfort would permit. I never had a 3304, naturally aspirated, ever overheat. My 3304 Turbo would start climbing only if over 85 - 90 F outside summer temp. and that's really working the machine hard.

I tried to flush it with some chemical stuff. Didn’t change much.
What’s weird is that the inlet and outlet of the radiator still have a temperature difference of almost 40F.
For what ever reason the coolant just gets super hot in/behind the water pump.

Do faulty water pump impellers on the 3304 tend to fail when the engine is at operating temperature?

I also believe that the cooling system either has a blockage problem somewhere or a flow problem… or something else - lol.

 

[wore out]

I tried to flush it with some chemical stuff. Didn’t change much.
What’s weird is that the inlet and outlet of the radiator still have a temperature difference of almost 40F.
For what ever reason the coolant just gets super hot in/behind the water pump.

Do faulty water pump impellers on the 3304 tend to fail when the engine is at operating temperature?

I also believe that the dozer either as a blockage problem somewhere in the coolingt system or a flow problem… or something else - lol.

I really hope someone can help me and point me in the right direction:

I recently acquired a 1972 Cat D4D dozer, which I believe has a power shift. I was told that it had sat for 4 years in the field. Unfortunately, once I started working with it, it began to overheat severely. I'm not referring to any strenuous activity; this happens simply when driving in, for example, second or any other gear.

Now, the strange thing is that at idle or high idle, I can let it run for an hour or longer. It does slowly climb above the thermostat opening temperature (taking 45-60 minutes), and then the temperature basically stabilizes there. I didn't manage to overheat it when just high idling. I let it run for almost 2 hours with no issues.

However, once I drive it, it takes less than 10 minutes before it reaches the red zone on the temperature gauge. After a cold start, I may get about 20-30 minutes or so.

I checked the thermometer; it seems accurate. The red zone starts at around 210°F-215°F.

I also measured the entire system from top to bottom. Here are the readings from the infrared thermometer at operating temperature (regulator/thermostat open):
- Thermostat housing: 180°F
- Radiator inlet: 178°F
- Radiator outlet: 143°F
—> The radiator seems to be fine.
- Pump top/outlet: 180°F
- Pump bottom: 142°F
- Oil cooler in: 180°F
- Oil cooler out: 193°F
- Transmission oil in (not driven): 184°F
- Transmission oil out: 195°F

I also measured the pump pressure:
- Pump pressure cold: around 15psi
- Pump pressure warm: less than 10psi

Unfortunately, I only had a pressure gauge from a compression tester. It's hard to tell if it's 9psi or 5psi for the pressure when warm (180°F), but it drops significantly compared to when the thermostat is closed.

The thermostat is new.
A block test was negative (blue).
There are no bubbles in the radiator.
There is no oil in the coolant and no water in the oil.
No external coolant leaks.

Does anyone have an idea of what I could look for next or what could be causing this?

Did you install the correct thermostat by application/part number or something that fit by outside diameter?

I would ASSUME this uses a t-stat that provides a bypass to recirculate the coolant through the engine during warmup which is gradually blocked off as the thermostat opens and the flow is diverted to the radiator. Sometimes there is a replaceable seal down in the area where the thermostat fits that works along with the thermostat to separate the recirculation and radiator flows.

If something is not as it should be with the parts I've mentioned that could be the cause of hot coolant recirculating through the engine instead of being pushed to the radiator to be cooled.

 

[Greenfielrider]

Did you install the correct thermostat by application/part number or something that fit by outside diameter?

I would ASSUME this uses a t-stat that provides a bypass to recirculate the coolant through the engine during warmup which is gradually blocked off as the thermostat opens and the flow is diverted to the radiator. Sometimes there is a replaceable seal down in the area where the thermostat fits that works along with the thermostat to separate the recirculation and radiator flows.

If something is not as it should be with the parts I've mentioned that could be the cause of hot coolant recirculating through the engine instead of being pushed to the radiator to be cooled.

I installed the correct thermostat by part number.

Good idea. There is a bypass (a metal pipe, around 0.5“ diameter).
How is the bypass being blocked off as the thermostat opens?

 

[Jerry/MT]

I really hope someone can help me and point me in the right direction:

I recently acquired a 1972 Cat D4D dozer, which I believe has a power shift. I was told that it had sat for 4 years in the field. Unfortunately, once I started working with it, it began to overheat severely. I'm not referring to any strenuous activity; this happens simply when driving in, for example, second or any other gear.

Now, the strange thing is that at idle or high idle, I can let it run for an hour or longer. It does slowly climb above the thermostat opening temperature (taking 45-60 minutes), and then the temperature basically stabilizes there. I didn't manage to overheat it when just high idling. I let it run for almost 2 hours with no issues.

However, once I drive it, it takes less than 10 minutes before it reaches the red zone on the temperature gauge. After a cold start, I may get about 20-30 minutes or so.

I checked the thermometer; it seems accurate. The red zone starts at around 210°F-215°F.

I also measured the entire system from top to bottom. Here are the readings from the infrared thermometer at operating temperature (regulator/thermostat open):
- Thermostat housing: 180°F
- Radiator inlet: 178°F
- Radiator outlet: 143°F
—> The radiator seems to be fine.
- Pump top/outlet: 180°F
- Pump bottom: 142°F
- Oil cooler in: 180°F
- Oil cooler out: 193°F
- Transmission oil in (not driven): 184°F
- Transmission oil out: 195°F

I also measured the pump pressure:
- Pump pressure cold: around 15psi
- Pump pressure warm: less than 10psi

Unfortunately, I only had a pressure gauge from a compression tester. It's hard to tell if it's 9psi or 5psi for the pressure when warm (180°F), but it drops significantly compared to when the thermostat is closed.

The thermostat is new.
A block test was negative (blue).
There are no bubbles in the radiator.
There is no oil in the coolant and no water in the oil.
No external coolant leaks.

Does anyone have an idea of what I could look for next or what could be causing this?

"Oil cooler in: 180°F
- Oil cooler out: 193°F"

Are you sure that this correct. The cooler outlet temperature should read less than the cooler inlet temperature. Are the lines hooked up correctly?
Is the air side of the radiator clean? It's not uncommon for the air side to be blocked with chaff, dirt, etc. Is the radiator cap holding pressure? Is the water pump drive belt slipping? Is the lower hose collapsing at higher rpm? Are the injectors leaking? Did someone turn up the fuel? Is your air filter clear? Is a brake dragging?

Starting with a cold engine, remove the radiator cap and start the engine, bring the engine up to temperature and while looking in the radiator, watch for the thermostat to open. You should see a sudden rush of coolant entering the radiator, increasing as the thermostat opens. measure the temperature of the thermostat housing when it opens. Is it opening at the correct temperature

 

[Greenfielrider]

"Oil cooler in: 180°F
- Oil cooler out: 193°F"

Are you sure that this correct. The cooler outlet temperature should read less than the cooler inlet temperature. Are the lines hooked up correctly?
Is the air side of the radiator clean? It's not uncommon for the air side to be blocked with chaff, dirt, etc. Is the radiator cap holding pressure? Is the water pump drive belt slipping? Is the lower hose collapsing at higher rpm? Are the injectors leaking? Did someone turn up the fuel? Is your air filter clear? Is a brake dragging?

Starting with a cold engine, remove the radiator cap and start the engine, bring the engine up to temperature and while looking in the radiator, watch for the thermostat to open. You should see a sudden rush of coolant entering the radiator, increasing as the thermostat opens. measure the temperature of the thermostat housing when it opens. Is it opening at the correct temperature

Sorry my bet. The readings are backwards.
I already cleaned the radiator fins. But they were clean before.
Rad cap holds pressure.
The belt is not slipping and the lower hose isn’t collapsing at high rpm’s.
I‘m not sure about the injectors. How can I test them? Any other symptoms I can look for?

Already cleaned the air filter and IMO no dragging brake.
And there is also a rush of coolant when the thermostat opens.
What I did notice is that the coolant level is basically pulsating. So it comes in kinda waves that increase and decrease the coolant level in the radiator filler neck (6-8“ long) by up to 2-3“. So it’s not a constant flow, even when the thermostat is fully open.

How can I check if someone turned up the fuel?

 

[Fixingfarmer]

Your 40 degree drop on the radiator is perfect if you completely lost a water pump it would be ice cold below 100 at the lower pipe but I suppose the direction I’d take in order.
1. That air filter make sure there’s no restriction.
Also is it smoking a lot? grey smoke fuel black smoke plugged air inlet. While your at it check turbo for wiggle up and down on the shaft. Checking this is free if you find something turbo wise expensive.
2. clean radiator cores I think this is going to have individual cores with 2 hose barb like ends on each that come out for easy complete cleaning or replacement. Then these flat rubber seals at the bottom. I don’t remember if the little ones had this but d6 d8 that was how they were.
Cant tell you how many of these we replaced. Checking and cleaning free except seals if you pull them. None pumice hand soap from caterpillar was the stuff to use to get them back together.
3. Thermostats I believe there’s 2. Cheap
4. Water pump. Could possibly be the impeller is worn down. At this point if you do that best wash down the block as best you can there should be plugs or a valve if your lucky and the thermostats need done for sure.

 

[WNM]

From all your troubleshooting results I would suggest a water pump also

 

[Greenfielrider]

Your 40 degree drop on the radiator is perfect if you completely lost a water pump it would be ice cold below 100 at the lower pipe but I suppose the direction I’d take in order.
1. That air filter make sure there’s no restriction.
Also is it smoking a lot? grey smoke fuel black smoke plugged air inlet. While your at it check turbo for wiggle up and down on the shaft. Checking this is free if you find something turbo wise expensive.
2. clean radiator cores I think this is going to have individual cores with 2 hose barb like ends on each that come out for easy complete cleaning or replacement. Then these flat rubber seals at the bottom. I don’t remember if the little ones had this but d6 d8 that was how they were.
Cant tell you how many of these we replaced. Checking and cleaning free except seals if you pull them. None pumice hand soap from caterpillar was the stuff to use to get them back together.
3. Thermostats I believe there’s 2. Cheap
4. Water pump. Could possibly be the impeller is worn down. At this point if you do that best wash down the block as best you can there should be plugs or a valve if your lucky and the thermostats need done for sure.

Thank you for your advice.
1. The air filter is clean. It doesn’t smoke. No turbo

2. But the temperature difference in the radiator seems to be good —> 40F difference top/button. Should I really clean it anyways??

3. I already replaced it. As far as I know only 1 thermostat.

4. The water pump is also my #1 suspect. There is a rubber hose next to the water pump. When the thermostat is closed, I can barely squeeze it. Once it’s at operating temp, I can easily squeeze it.
Is that normal?? Shouldn’t the pump be able to somewhat maintain the pressure even with the thermostat open?

 

[Jerry/MT]

Sorry my bet. The readings are backwards.
I already cleaned the radiator fins. But they were clean before.
Rad cap holds pressure.
The belt is not slipping and the lower hose isn’t collapsing at high rpm’s.
I‘m not sure about the injectors. How can I test them? Any other symptoms I can look for?

Already cleaned the air filter and IMO no dragging brake.
And there is also a rush of coolant when the thermostat opens.
What I did notice is that the coolant level is basically pulsating. So it comes in kinda waves that increase and decrease the coolant level in the radiator filler neck (6-8“ long) by up to 2-3“. So it’s not a constant flow, even when the thermostat is fully open.

How can I check if someone turned up the fuel?

"I‘m not sure about the injectors. How can I test them? Any other symptoms I can look for?"

You'll have to pull them and take them to a diesel shop. They can clean, check the pop off pressures, check for leaks,etc. Or you can pull them out and then crank the engine to pressurize them and they should hold pressure and not drip. It's worth it to get them cleaned and checked on an old machine.

"What I did notice is that the coolant level is basically pulsating. So it comes in kinda waves that increase and decrease the coolant level in the radiator filler neck (6-8“ long) by up to 2-3“. So it’s not a constant flow, even when the thermostat is fully open."

The flow should be fairly steady not pulsating. If the belt isn't slipping, I don't understand the pulsing. I'd check the water pump for a loose impeller or a damaged impeller. Can you see inside the engine water jacket? Is there any chunks of lime or calcium deposits?

From your first post:
"Now, the strange thing is that at idle or high idle, I can let it run for an hour or longer. It does slowly climb above the thermostat opening temperature (taking 45-60 minutes), and then the temperature basically stabilizes there."

It takes a long time to warm up at both high and low idle because there is hardly any load on the engine so the fuel/air ratio is low and therefore the peak temperature in the cylinders is much lower than when you have load applied. So it takes a long time to warm up. On a spark ignition engine, the peak cylinder temperatures don't change much because the fuel/air ratio is relatively constant so the peak temperatures are relatively constant. So the engine warms relatively quickly at idle.

 

[Greenfielrider]

You'll have to pull them and take them to a diesel shop. They can clean, check the pop off pressures, check for leaks,etc. Or you can pull them out and then crank the engine to pressurize them and they should hold pressure and not drip. It's worth it to get them cleaned and checked on an old machine.

Ok - I will try to remove them. Now this is a fairly old machine without electronic injectors. It has precombustion chambers and nozzle style injectors that are similar to those in an (old?) oil furnace.
Is it the same procedure for those ancient “injectors”?

The flow should be fairly steady not pulsating. If the belt isn't slipping, I don't understand the pulsing. I'd check the water pump for a loose impeller or a damaged impeller. Can you see inside the engine water jacket? Is there any chunks of lime or calcium deposits?

No lime or calcium deposits that I can see but a bit of rust. Before I flushed the cooling system and replaced the coolant, the coolant also had lots of rust in it. It’s now much better. I will check the water pump today.

It takes a long time to warm up at both high and low idle because there is hardly any load on the engine so the fuel/air ratio is low and therefore the peak temperature in the cylinders is much lower than when you have load applied. So it takes a long time to warm up. On a spark ignition engine, the peak cylinder temperatures don't change much because the fuel/air ratio is relatively constant so the peak temperatures are relatively constant. So the engine warms relatively quickly at idle.

Thank you for explaining this. That is very good to know. Maybe it runs a fair bit lean due to blocked nozzle-injectors. It doesn’t smoke at all, even when accelerating or applying a good load. I guess technically a good sign but imo uncommon in 50 year old machines.

 

[Jerry/MT]

Ok - I will try to remove them. Now this is a fairly old machine without electronic injectors. It has precombustion chambers and nozzle style injectors that are similar to those in an (old?) oil furnace.
Is it the same procedure for those ancient “injectors”?



No lime or calcium deposits that I can see but a bit of rust. Before I flushed the cooling system and replaced the coolant, the coolant also had lots of rust in it. It’s now much better. I will check the water pump today.


Thank you for explaining this. That is very good to know. Maybe it runs a fair bit lean due to blocked nozzle-injectors. It doesn’t smoke at all, even when accelerating or applying a good load. I guess technically a good sign but imo uncommon in 50 year old machines.

I think you have the CAT 3304 NA engine. If so, everything I see on web for this engine indicates it has a gear driven water pump. Can anyone confirm this? If it is gear driven, I would suspect a problem with worn bearings and/or damaged impeller. There are rebuild kits available as well as remanufactured pumps.

 

[Greenfielrider]

I think you have the CAT 3304 NA engine. If so, everything I see on web for this engine indicates it has a gear driven water pump. Can anyone confirm this? If it is gear driven, I would suspect a problem with worn bearings and/or damaged impeller. There are rebuild kits available as well as remanufactured pumps.

Yep, it’s gear driven.
I really hope that it’s just the water pump. This would be an easy fix.
I’m about to remove it now.