Did some heavy hauling for the first time with my new truck the other day (what I bought it for) and I had some cooling issues.

I was hauling about 14,000 pounds (quite the first test for hauling with my new truck) and to make it better I was headed up a 7% grade for 5 miles going over a pass in Colorado. I was doing great on power I was holding about 25mph. Just about as soon as I hit the first hill the temp gage started to heat up and flew right to overheating. I pulled over let it cool by idling and then started again only to find my self a 1/4 mile further. Having 4 more miles to go I called a buddy and had him bring some coolant as I thought I must be low.

I let the engine cool down and then popped open the lid and to my big surprise it was full. So then I went to the thermostat thinking something must be wrong with it. I took out the guts of the thermostat and put it back in (needed to take out the guts because the o-ring is around the edge of the thermostat housing). Started the truck back up and started up the hill again. I had good power and the cooling was noticeably better. This time I got about 2 miles before it overheated. When I pulled over it cooled down MUCH faster and I started up the hill again and made I to the top. After the hill the remainder of my ride was up and down so it would heat up and cool off but stay within reason. When I got home I drained some coolant to check it and it tested good and looks good in color (not brown nasty).

The next day I hauled a skid steer (about 8k total) and the truck was still just about to over heat. (I can haul a skid steer with my 1/2 ton and it doesn't overheat)

To me water pumps either work or they don't and obviously mine is working or I would have problems with normal driving. I've never heard of a water pump loosing efficiency. My coolant is good and my thermostat I also believe is ok (I have replaced now).

So the big question is what am I missing?

 

I just had the same experience towing a load across Colorado passes ( i even stopped and cut my thermostat out and noticed the same results) It started overheating on this trip, having made similiar trips and not overheating- so it seemed something had just gone bad. Changed fan clutch in durango, water pump and thermostat in co springs. pump was bad?-had seal inside flopping around but wasn't weeping, fan clutch made minor difference cruising, still overheated immediately on climbs. Didn't suspect the radiator because the coolant looked great, no corrosion on pump etc, radiator and intercooler fins were clean ( no oil on the inside). Well, after thowing parts at it, finally changed the radiator, now has no problems whatsoever.

The fan clutch really was bad, but a new one couldn't overcome radiator, I have no doubts nothing was wrong with thermostat

 

The most likely problem is really a simple fix. The crankcase vent on these trucks dumps greasy gunk on the front of the engine. You'll probably find the backside of the radiator gunked up with greasy residue that has picked up a bunch of dirt and dust.

The end result is a good portion of the radiator won't flow any air at all, and you'll have a cooling system what can barely dump heat and will overheat.

So spray the backside of the radiator with some Simple Green or or other strong degreaser and hose it off really well (no pressure washing!). Clean that gunk off and your overheating should go away.

If it doesn't your auto trans might be causing the overheating (if you have one). The tranny fluid on a factory auto trans can get hot enough to cause the engine to overheat.

After that, it's things like thermostat checks and coolant changes and other such things to try and isolate a gremline.

There's a good chance it's a gunked radiator, though

 

After a little research, i pulled my radiator to take a better look, no clogging whatsoever from overflow oil-vent drains to ground, radiator was surprisingly clean. Also, my tranny (auto built by fred swanson) sits abut 160-175 towing on flat ground, rarely exceeds 200-210 on long grades (passes in colorado). I changed the radiator really thinking it wasn't going to help much, but it was the only thing left!

 

I wouldn't say that's the only thing left... the fact that you haven't solved the issue says that there's something left. Have you flushed your cooling system?

Also, excuse my ignorance, but I'm a diesel newb. If the timing is off can that cause overheating? I know it works that way with a gasser, but not sure if that applies to the diesel world. Possibly something worth looking into.

 

Slipped timing can cause things to run a little hotter, but not as much as on a gas engine. This is because as the EGT rises from the retarded timing, the turbo makes more boost, forcing more air into the engine and lowering EGT-- so it's a partially self-correcting phenomenon.


I'd do a really good flush.

Then I'd fill it with some Evans NPG+

www.evanscooling.com

jmo

 

I have a stock 3500, pulling long grades with a load I can get it to overheat. Get an EGT gauge ASAP and keep it under 1200 Deg. pre turbo. Stock, mine will run close to 1400 Deg with the pedal to the metal, keeping the EGT's under 1200 I haven't had a problem. I also clean the oil out of the radiator from the puke bottle once a year.

 

got otthe dodge dealer and get the upgrade high flow t-stat it is a TSB part if you dont ask for it you wont get it type thing, p/n 5015708AC and that is part of TSB 09-008-02, this t-stat and good coolant/antifreeze mix has always helped my fleet customers with these syptoms.

 

i called the local dealer and they want $61 for that tstat.
cummins nw has them for $26. you'll need your engine serial number for them to look up the correct highflow for you.

 

Great stuff guys... would that upgraded Tstat work any better than taking it out completely like I did when I was overheating. I will check the back side of my radiator tomorrow

 

I've had the same experiences and found the problem because of my igornance. More antifreeze or 100% antifreeze isn't good, it just doesn't cool and runs hot. Drain some of the antifreeze out of your radiator and fill it with distilled water. If it's dark rich green coolant, it probably has too much antifreeze and not enough water.

The antifreeze is too thick and doesn't transfer heat efficienctly. A 50/50 blend transfers more heat quicker and efficiently. You just have to find the right blend that suits your needs. Consider how cold and hot the environment will be and towing or not towing. This will determine if you need 50/50, 60/40, or evn 70/30 blend.

I like the premixed coolant available, because the water is distilled and free of minerals.

 

Another area to check is the front of the radiator between the A/C condenser and radiator. Mine was full of cottonwood fir (?) just where the fan pulls the hardest. I took the air hose and poked a piece of cardboard down between them and gently blew it out. Luckily I had already move the crankase vent so there wasn't any oil mist to really make a mess. I didn't notice untill it got reallyhot like in the upper 90's and I was in slow traffic with the air on high. the temp gage went only about a needle width higher but when you drive the truck everyday you get to know every little quirk and sound.

Apparently air flow can go over the top of the radiator and dump all this stuff floating in the air right where the fan pulls.

One other thing, if you check with the thermodynamic guys they say that pure water (distilled) is the best coolant. It can transfer more heat quicker than with AF in it. However they also say that you need enough AF to provide lube for the water pump. No more than 25%.

 

I have over heating problems at idle when I pull stuff. I don't have a problem while running down the road. So I'm guessing its an air flow problem. I have already replaced the T-stat and flushed the antifreeze. I have a fan clutch that I can install. I'm going to check the back of the radiator and make sure that its not all gummed up. Any other advice?

 

...........Even though it don't look bad the rad is really plugged up with oil scuzz...........kim...

 

I don't know what kind of miles are on your truck or how it was serviced, but I read a while back a guy pulled his water pump to find almost no teeth left on the vanes after he overheated...

Are you popping off the radiator cap or just running hot?