Hi all. We took our new 5th wheel toy hauler out for it's maiden voyage - had a ball. Towing on the flats and minor grades / hills was fine, had power to spare but would like a little more. However, once we got to Ice House road and started pulling the 12 mile 25mph grade, the engine temp got really hot. So we pulled over, the temp came back down to safe range but it was scary to say the least. We got to the campgound and let her cool down for a few hours, started it up, drove around and all was fine. Towed it back home with no problems.

So I heard from a guy at the campground that the Dodge trucks run the trans coolant thru a heat exchanger on the side of the block and as the tranny fluid heats up, it heats the engine coolant and thus, the temp guage soars. Anyone heard anything about this? I could hear my fan clutch roar (slightly). I'm wondering what I can do to cure this. I was going to buy a new fan clutch just for the heck of it since mine has about 100k on it. Also, do the '99s come with an auxiluary cooler on the radiator for the trans? If not, can I bypass this heat exhanger thing?

Thanks very much. Mike.

 

Can't tell you much about your auto tranny but I would so extremely encourage an EGT guage here. EGT's are just as important if not more then the water temp. If the water overheats it just blows a hose or gasket more then likely, if your EGT's over heat you melt the pistons.

I've never heard of the tranny fluid runnin around the motor but could be. I know you can buy auxillary tranny coolers for less then $100 in some cases. I'd also suggest changin the thermostat in case it's stickin and this is just somethin simple. Was their any indication of leakage, as in is you fuid low now. If so I would also change the radiator cap. If it's not holding the right pressure it won't force it's way through the engine block right and doesn't circulate.

 

Thanks Uncle Bubba, no indication of coolant leakage - radiator was full; overflow bottle to full level, trans fluid was within safe range. I wonder if my fan clutch could be flakey? When I've driven in 106* temps, the engine never went over 190* (even towing). Most of the time it stays well below that.

What temps should it stay at when towing? I only have a timing box on it now... no fuel.

If I was pulling a 12k load up a long grade in 2nd gear at about 2200 rpms, shouldn't my fan clutch pull enough air to cool the engine? Are EGTs an issue with a basically stock engine?

Mike

 

To check the fan clutch just turn it by hand. It should have tension on it but be able to manually push it.

The fueling boxes will affect the EGT's in a huge way but do very little to nothin for the water temps.

EGT's and your fueling box. If your hauling or towing and have the stock turbo and/or stock exhaust the box needs to be turned way down if it is adjustable and off if it's now adjustable. They will heat up in a hurry with the extra fuel. 1200 degrees is a safe short term max temp on EGT's but personally my truck has never gone above 1000 degrees and only that high on short runs tryin to climb hills with overweight trailers. Normal operating temps just runnin down the road stay around 300-600 degrees with my stock turbo and RV275 injectors.

On the water temps. I'd hate to answer that one becuase I've heard so many different opinions. Some people say these Cummins motors do best when they run a little hot, up around the 210 degree mark and some say they need to run a little cooler and by the 180 degree Thermostats. So once again personally I would pull over if the truck hit the 220 degrees.

Now having said all this these other guys are gonna come on here and tell you they hit over 1400 degree EGT's all the time along with higher water temps. I stay conservative in my truck, it has to last me. I increased the HP and capabilities of my truck so that I never had to push it to the limit, not so that I could push the limit higher. So all this is just opinions here.

 

Good info, thanks.

The fan clutch is just as you said - it has tension but can be turned by hand. I'm basically stock except the timing box so I'm at a loss. What do you consider an 'overweight' trailer?

 

On your Auto I think it's around the 16,000 mark stock. I pull trailers pretty regularly during the summer up to 30,000 maybe a little more when you include the trailer itself. I've got a 40 foot flatbed with three 7000 pound axles that I have modified and reinforced.

 

Is your blowby bottle still in the factory location? If so, b4 I took the bottle off of my old truck and extended the hose down, the bottle would keep the blowby and oil mist contained by the radiator. After 148k miles the blowby was built up on the engine side of the rad basicly clogging the cooling fins all to hell! I always wondered y the truck ran warm b4 that.... You can't tell from lookin at the outside of the rad, you have to climb under her with a light and shine it up there. You should be able to tell right away if its clogged up with oil or not... Just an idea

 

I took that thing off so many years ago I forgot all about it. Yea this blowby residue will clog the backside of the radiator up good if it's allowed to. Me bein the simple minded person I am just used a 2' piece of black PVC and cut it off so it drains just under the axle level. I use the threaded end to twist it up into the rubber hose and just use it as an extension. Don't remember if it's 1/2" or 3/4" pipe I used though.

 

I had the same thing on my 02. I took the radiator out and it was nearly 2/3rds blocked with some kinda goop. I used degreaser on it with a low pressure hose and it cleaned up pretty well. No problems since.

 

to answer you question bout the tranny fluid, the answer is no. THe tranny fluid has its own cooler/pump. no tranny fluid every goes near the coolant inside the motor. there is no "heat exchanger". i had my auto tranny out several times in my old 98.5 and i can tell you that the lines run directly to a small cooler in front of the radiator.

also, when was the last time you flushed you cooling system?? if its been a while or you dont know, go do it. old antifreeze can loose its cooling ability over time and it can create the very problem you described, because as antifreeze wears out, it gets clumps of lime in it and those clumps can build up under heat and clog your coolant passage ways inside the motor, not good.

hope this helps