1972 CAT D4D overheating

[Jerry/MT]

I just looked closely at the image of the engine side of the pump housing. Where is the gear that meshes with the gear on the water pump?

 

[Greenfielrider]

Your problem is more than likely the same problem as why the machine was parked in the first place, there has to be a reason it was parked, those were great dozers but were prone to the liners coming loose and the heads cracking should they get hot and have cold water poured in. have a Cat mechanic look at it for you..
AJ

But a cracked head or loose liner would cause a positive block test… right?

 

[Milk]

So if thermostat is done I’d still suggest cleaning those cores as good as possible. Then going at the water pump it’s going to be kinda spendy you don’t want to throw a 1000 dollar pump in and find out you need to clean the cores at the end. I think you are right pump is where this is headed. But I have seen a lot come out of what was thought to be a clean radiator. And it help significantly

 

[Milk]

So if thermostat is done I’d still suggest cleaning those cores as good as possible. Then going at the water pump it’s going to be kinda spendy you don’t want to throw a 1000 dollar pump in and find out you need to clean the cores at the end. I think you are right pump is where this is headed. But I have seen a lot come out of what was thought to be a clean radiator. And it help significantly

I just looked closely at the image of the engine side of the pump housing. Where is the gear that meshes with the gear on the water pump?

I had similar problems with my caterpillar d-6c . I had to replace water pump because it was weak impeller cat tech said and was bypassing water, also replaced radiator because rust and water deposits were restricting water flow. Those two issues resolved the problem and works great now! Just my two cents worth!

 

[Greenfielrider]

I installed a new water pump today and had the radiator cleaned. I also replaced the transmission filter and changed the milky transmission fluid.

After a 15-minute test ride, everything looked good, with the temperature gauge on the lower end of the green area. However, 10 minutes later, I noticed that the coolant temperature began to rise. Five minutes after that, it was in the red area again, dang!

Now, the weird thing is that when I started the engine after turning it off to check the coolant level, the coolant temperature rapidly declined. It went from red to normal in around 20 seconds. The engine was only off for maybe 2-3 minutes. 10 minutes later, it was in the red zone again…

Could this be an airlock, or is it a symptom of something completely different?

To me, it looks like something is restricting the coolant flow, but I really don’t understand how it would be possible for this to change just by turning off the engine for a couple of minutes.

I also noticed that the air in front of the radiator is colder when it’s overheating (gauge in the red zone) compared to when the dozer has a normal temperature (175-180F). In this temp range the air that’s coming from the rad is warm, like you would expect it.

 

[Nordic]

What you're describing reminds me of an account I heard some years back in an automotive application I believe. Much the same scenario where overheating was a mystery. It turned out, long at last, that some metal piece, that possibly came loose from the casting itself, something to that effect, and it would block coolant flow to cause overheating. Just a thought...

 

[Fixingfarmer]

Often if it’s a rag or something it will find its way to the impeller hole of the water pump. We had an engine years ago in a fertilizer machine dampener fell off went through the radiator. Engine had about 6 hours on it. It was a new brand of engine in said fertilizer machine and they let us keep the core for training the new mechanics. I happened to be in the first group that took it apart. Behind the water pump was a bright white assembly rag partially pink from the antifreeze but still mostly white. If the dampener hadn’t fallen off it wasn’t going to live long anyways.

 

[Greenfielrider]

At this point, I also think that something is stuck in there or that something is restricting the flow.

The bypass from the water pump to the thermostat housing had some weird temperature readings: 170°F on the side of the thermostat, 140°F on the side of the water pump, and 80°F a quarter way from the housing down to the water pump.

I have no explanation other than something is restricting the flow in that are, why else would it be almost 100°F cooler compared to the rest of the pipe…?

 

[Jerry/MT]

At this point, I also think that something is stuck in there or that something is restricting the flow.

The bypass from the water pump to the thermostat housing had some weird temperature readings: 170°F on the side of the thermostat, 140°F on the side of the water pump, and 80°F a quarter way from the housing down to the water pump.

I have no explanation other than something is restricting the flow in that are, why else would it be almost 100°F cooler compared to the rest of the pipe…?

Can you take a picture of the installation and what the locations are for temperatures you are measuring? Are you sure that the wax pellet on the thermostat is pointing toward the engine? Are you sure you have the right thermostat? There appears to be about a dozen configurations for the 3304 and different thermostat housings.

 

[Greenfielrider]

Yes to all your questions. Pictures are attached.
According to the service manual, there are two different thermostats. I installed a thermostat similar to the one that was installed before.

Not sure why there are two different thermostats in the service manual. It definitely only has ONE installed and not two like more modern engines.

 

[wore out]

Yes to all your questions. Pictures are attached.
According to the service manual, there are two different thermostats. I installed a thermostat similar to the one that was installed before.

Not sure why there are two different thermostats in the service manual. It definitely only has ONE installed and not two like more modern engines.

"I installed a thermostat similar to the one that was installed before."

As I wrote in Reply #10 to this thread, if the thermostat and housing don't match and a bypass is involved that could be causing your problem.

Is there a photo or drawing of the two different types in the manual that you could post?

If you tear into it again can you post a photo of the 'stat you are using and a view down into the thermostat housing with the thermostat removed?

 

[Greenfielrider]

The part 9S3808 was installed previously and has been replaced with the same part (9S3808 but from Napa). The opening temperature of the new thermostat is slightly lower (175°F). Other than that, there is no difference.

I haven’t figured when to use part 7N208 and when 9S3808. 7M208 seems to open a bit more (minimum 7.87mm vs. 9.53mm). Both the new and old thermostats fit perfectly fine in the housing. Cat also told me that 9S3808 is the right thermostat for this tractor.

 

[Fixingfarmer]

Caterpillar had many choices for thermostat based on operating temps to this day Otr truckers will want 175 degree thermostats put in an acert engine that’s designed to be 215 degrees for emissions. 175 degree thermostats should be fine for this. 190 should also be fine for this unless you live down south.

No I mean the temperature differential between the top and the bottom hose of the radiator. So the radiator inlet and outlet. I measured a temperature differential of 30-40F.
Which I thought is good?

Is there any way to clean the radiator without removing it?
Besides that I have no idea how to remove it, it looks like a major pita to get that thing off the dozer. Let alone to remove all those rusted bolts to get the core out.

230 is pretty much what I have if I don’t pay attention…. Couple more of those test runs and at some point I will also need a new head gasket…

you should be able to clean the radiator with it on the machine carefully with a Hotsy you might have to take the brush guard off

 

[Fixingfarmer]

I suppose take the pipe out and clean it that is kinda weird does the upper end go to the thermostat housing? 175 or 190 thermostat should be fine 175 should improve the operation of it if you are having trouble how you describe caterpillar had options on thermostat based a lot on customer preference and where they were located. Some of these things got sent to Antarctica and others to Iraq. The USA is in a fun spot in the middle where it doesn’t really matter if the rest of the cooling system is working. A lot of those big ones won’t fit in the housing but one direction so it would probably be kinda hard to mess that up.

 

[Nordic]

Out of curiosity it would be interesting to see the temperature readings if the thermostat was removed altogether??

 

[Jerry/MT]

Yes to all your questions. Pictures are attached.
According to the service manual, there are two different thermostats. I installed a thermostat similar to the one that was installed before.

Not sure why there are two different thermostats in the service manual. It definitely only has ONE installed and not two like more modern engines.

If I read this correctly, the 153 F is located at the lower end of the bypass line and the 84F is located at the top of the bypass line. The top of the by pass takes coolant from the engine and bypasses around the thermostat housing. SO the bypass line should be at the same temperature throughout its length. When the thermostat is open, some of the flow goes past the thermostat and some goes through the bypass line. and it combines somewhere and goes into the radiator. I think there is something wrong in your bypass system. Have you checked that?

 

[Greenfielrider]

I suppose take the pipe out and clean it that is kinda weird does the upper end go to the thermostat housing? 175 or 190 thermostat should be fine 175 should improve the operation of it if you are having trouble how you describe caterpillar had options on thermostat based a lot on customer preference and where they were located. Some of these things got sent to Antarctica and others to Iraq. The USA is in a fun spot in the middle where it doesn’t really matter if the rest of the cooling system is working. A lot of those big ones won’t fit in the housing but one direction so it would probably be kinda hard to mess that up.

Took the pipe out and checked it, it is basically as clean as it gets. Nothing was stuck in there…. Oooor it moved, well hopefully not!

 

[Greenfielrider]

If I read this correctly, the 153 F is located at the lower end of the bypass line and the 84F is located at the top of the bypass line. The top of the by pass takes coolant from the engine and bypasses around the thermostat housing. SO the bypass line should be at the same temperature throughout its length. When the thermostat is open, some of the flow goes past the thermostat and some goes through the bypass line. and it combines somewhere and goes into the radiator. I think there is something wrong in your bypass system. Have you checked that?

Do you mean with bypass system the pipe? There is a way smaller pipe -

If I read this correctly, the 153 F is located at the lower end of the bypass line and the 84F is located at the top of the bypass line. The top of the by pass takes coolant from the engine and bypasses around the thermostat housing. SO the bypass line should be at the same temperature throughout its length. When the thermostat is open, some of the flow goes past the thermostat and some goes through the bypass line. and it combines somewhere and goes into the radiator. I think there is something wrong in your bypass system. Have you checked that?

Completely agree! It should be the same temperature. I checked the „big“ pipe. I haven’t checked the other smaller pipe yet.

 

[Cash4Toys]

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?

This hose you are talking about in this post, did you investigate that further? Where dose this hose run to from? Is it part of the bypass system?

 

[Greenfielrider]

This hose you are talking about in this post, did you investigate that further? Where dose this hose run to from? Is it part of the bypass system?

Yes, the bigger one is part of the bypass system. The small one - idk.
Picture attached.