CAT D6 9U getting hot, not cooling

I recently acquired a CAT D6 9U #9U9709 dozer with
hydraulic blade. Service meter shows 0630 hours which don’t
appear original.
She sat for over 7 years before I got her so I’ve been going
through her, replacing fluids, greasing, etc. After some TLC
with the points and carb, I got the pony motor running. Diesel
started up fairly easy with pony motor. Upon running the
diesel, I noticed water temp climbed to 190 after 10-15
minutes of running at mid throttle while testing clutches and
hydraulics. I lowered throttle to low idle expecting temp to cool
down, but temp seemed to just stay at 190.
Upon inspection, there was no water in crank case oil or air
bubbles in radiator (while running), so doesn’t seem to be a
cracked head.
Upon troubleshooting the coolant system, I realized the water
pump is not circulating coolant into the radiator. I performed a
through coolant flush of the radiator and engine block.
Everything seemed fine with no apparent blockage.
Belt has proper tension, fan turns freely and blows like a
hurricane through the radiator, coolant level was filled within
1” of radiator cap after flush, water pump doesn’t leak, has
very little play in the bearings and runs quiet, just doesn’t
pump coolant.
I’ve checked the thermostats and they are not seized, but I
haven’t tested them to see if they open at 165.
I haven’t completely ruled out thermostats, but the fact there
is zero coolant flowing from the pump into the radiator has me
looking at the water pump.
Before I go any further troubleshooting, has anyone ran into
this issue or have any insight?
 
(quoted from post at 23:00:16 09/25/20) What temperature differential are you seeing between top and bottom radiator tanks?

Thank for the replies.

I ran the dozer this morning until water temp reached 190 (took about 20 minutes), then took 4 temp readings from the radiator.

Radiator temps:
Top Right: 89
Bottom Right: 83
Top Left: 86
Bottom Left: 80

Water temp gauge: 190 (new Bosch gauge)
Engine block temps: avg 185-190 (taken with laser temp gun)

Water block where thermostats are located was reading 200. I unscrewed the radiator cap off the radiator and was able to stick my finger in the fluid and it was just warm to the touch. If the water pump was moving any fluid at all into the radiator, the cap would be hot and fluid would be too hot to touch.

I'm puzzled and wondering if the water pump impeller could be slipping on the shaft? But like I mentioned yesterday, there is no rattling or noise at all coming from the water pump.
 
Given your laser gun readings, it looks to me like the thermostats are not opening. I would be checking the thermostats, suspended in a pan of water (they must not set on the bottom of the pan) and using a thermometer to watch the water temperature to see if and when they open. If they are not opening correctly, you likely won't see flow in the radiator, or it will be very small, which may explain your radiator readings. Remove the thermostats and run it it, see if you have flow.
 
The top tank has a baffle that makes it near impossible to detect flow.
Water pump impeller is keyed to shaft and is not likely the problem.
Check your thermostats.
 
Thanks for the tips. I only had a few minutes to mess with it this afternoon and the thermostats didn't want to budge, so I'll pull them next week as time allows.

Does anyone have the part number for the D6 9U thermostat or know where to purchase/download the service manual so I can look them up?
 
Things have changed.... looks like thermostat now. But be prepared for a shock when you get cost of parts !!!
There is discussion on uk forum about CAT spares
 
The reading between the top and bottom is not enough,it should be double that by the rule of thumb there should be 12 differ,the radiator is not as efficient as it should be,make sure that all of the core is clean,it could also be blocked internally,you could try backing flushing it if you got a hose,you might be able to connect the hose to the drain valve,take the cap off and let the hose run,if the water pump has not endured some heavy frost without antifreeze and the bearings are good I would leave it alone,you will not see much movement looking at the coolant because of a baffle in the rad,if you keep the heat gun on the top hose you can see at what temperature the thermostat/s open at as I also would leave them alone if they are opening in range,what happens if you keep on working the tractor,does it climb hotter or stay at 190.
AJ
 
I flushed the radiator and engine block last week and ran water through both top and bottom of radiator and engine block. I also removed front grill and thoroughly cleaned the radiator fins with a water hose. Radiator was actually pretty clean and had very little dirt in the fins.
I have not pulled and cleaned the radiator cores.

Temps will continue to rise until she's shut down. Temp only goes up and will not cool back down regardless of running at idle, mid or full throttle. If temps reach 195, it will only slowly rise to 200, etc. Usually takes 30+ minutes to go from cold start to 190 (which is where I start shutting it down).
 
Reading your first post again you seem to think that the water pump is not pumping,test it,take off the top hose when its hot and the thermostats open and see if its belching out water, I have known that during frost without antifreeze the water to be frozen in the pump the engine started causing the shaft to spin in the impeller so its loose and does nothing but that is far fetched but?.
AJ
 
I had a similar problem with my D6Cat . I found that the water pump shaft had play in it , water was bypassing the impeller.Also after removing radiator and having cat technicians check it out, they found the radiator core bottom tubes were mostly plugged with water scale, causing radiator to run hotter . I replaced the radiator and water pump, took care of the problem!
 
The usual way to clear the rad tubes is rod them using something like a gas welding rod very few people that we do work for would entertain replacing the core esp as it is a serviceable item,a PIA job but it saves a lot of money,at one time on every high street there would be a rad shop that would do the job,they had soak tanks and once done the core would be like new but now none of that,no tradesmen left,as I said before the reading you posted the differ between the top and bottom was only half what it should be,when the history of the machine is not known its not easy to be certain of what could be wrong.
AJ
 
I removed the housing above the thermostats and ran the diesel for a minute and confirmed there is water coming up through the bypass between the thermostats, so the pump does appear to be working.

While trying to remove the thermostats, I see there is some sort of retention ring above each thermostat that keeps them in place. How do I remove this? Not sure if it is pressed or threaded, but neither ring will budge.

Since I have not yet been able to remove the thermostats, I pried one of them open and reassembled the thermostat housing / hose back to the radiator and was able to run the dozer for over an hour before temps hit 200, so having one thermostat partially open has doubled run time before she heats up.
 
This is the proper tool for the job.
AJ
mvphoto62560.jpg
 
Thanks everyone for the tips. This has been a fun project so far and the advice given here has been very helpful.

Soon as I finish modifying a bearing puller I'll pull the retention rings and test the thermostats.

Last night I started installing LED work lights on the dozer. With the shorter days of Winter ahead, having lights on the dozer will extend my work... or play time. :D
 
I had that problem on a d69u water pump impeller had several hickory nut halves stuck in it. Must have sat with cooling system open before I got it.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top