EGT's are usually fine, but when I tow heavy, it seems like Im always between 3/4 and H, and the fan kicks off and on frequently. But it never really moves much from that spot, unless a long down hill/flat and it comes back to normal.

Are there any tricks to get this girl to run cooler? I already have a new Cummins Thermo.

Thanks

 

I dont know if this method works or not, But we always try and keep the RPMs up in a higher range when towing.
Such as downshifting.
Check the air filter, blow it out or replace it, it will be able to suck air and get rid of it quicker. Resulting in lower EGT's.
Just some of my advice!
Wheelo

 

If it's a non-intercooled truck, using a newer cross-flow radiator might be a good thing.

I had mine (92) rodded and that helped.

DBF

 

csramssey640 if your truck is like mine and is non intecooled, this is what i thing is going on.

the down flow radiator has allway been less efficient but what makes ours evan better is that the inlet and the outlet are on the same side.
so, in high flow times, the coolant flow in the fastes path, causing half of the radiator to flow vary slow!
the clutch fan keep kicking on and off evan tho the temp is still high.
with only 1/2 of the radiator "radiating' the fan can't deside if the radiator is hot or not.,
if yours in a cross flow then i would replace the clutch fan,cause it shouldn't disingage tell it cools. but if it is non intercooled like mine, a new one may not help...i replace my fan clutch a year or so a go(factory chry) and it will do the same thing when pulling a load up heal.
you would thing that as long as the temp is up high that the fan wouldn't disingage untill it cooled
just some thing to thing abought!

 

The fan control has no linkage to engine temperature. It's strictly its own little doo-dad on the fan shaft. Its a bourdon-tube-type of animal that expands under heat (heat right there on the shaft) and kicks in the fan. When the tube/spring on the shaft gets cooled enough by the incoming air, the fan free-wheels, regardless of what engine coolant temp is.

Its primitive and cheap.

OBTW, the more recent fan & controller combo's from the dealer are actually better than older ones. NAPA sucks in this area.

DBF

 

The first time my fan came on while on the highway I though I was being passed by a big truck! I was looking in the mirrors like what the heck is that behind me!!

 

I disagree, it the air form the radiator that heats up the fluid in the fan clutch and lock it up! Your thoery my hold some water on some engs but with the cummins the fan is on a bearing and not on the water pump.

Just reread you post and i sort of agree...if say, the thurmstate was to stay closed, and the eng over heated, then yes, the fan wouln't ingaged even thow the eng was over heating but, if every thing is working right the heat would constanly being going over the fan clutch casing it to say ingauged till it cooled enuff for the thurmstate to close and then the fan would disingage shortly there after!

EDIT if it an eary 91 or older,fan clutch from the deale,r then thay are gone, for ever, have allrready checked.
91.5 and up are still avalilabe!

 

I just read the FSM on engine cooling system diagnostic. Now I am not a good writer so bear with me on this and as always comments are requested.
Just picture your gauge, or better yet make youself a drawing. This will help in this clumsy attempt. Next to the "C" and "H" there are thick lines. In between these lines there is a semicircle divided into three equal spaces. Normal running under light load the needle should fall in the first space. It will hover around the small left edge of the segment and climb up to the right edge when the thermostat opens and it cycles back to the left. Under heavy load and moderate weather the needle should run in the right half of the cold segment and cycle into the next segmrnt about halfway. In other words it will cycle between 5 and 7o'clock on the gauge. Under heavy load and "HOT" driving conditions the needle should run in the right segment but only slightly better than midway between the borders of the hottest segment. As long as the gauge is working correctly the needle should only climb to within an 1/8 inch of the right edge of the hottest segment. I hope this isn't too confusing but it is the best I could come up with.

 

Thats exatly what my do's.....untill the fan desides to give up on pulling air and then it go in to the third segment,just barely but make me real nervice. i have to shift down and waight for the fan to ingage again!
Theres someting just not right and i don't think its the fan or thurm that's. at falt

 

Running in the third segment under heavy load and hot weather is normal. I would start worrying when it climbs better than halfway up in the third segment. I would also worry if it did at modest or less load or conditions. Whose thermostat are you running? There is a wide variation in manufacture and quality when it comes to T stats. If all else fails, put in a Cummins Part, if you can afford them. There is also a big difference in water pumps. Some have open face impellers and some have closed face impellers. Right now I am running a closed face impeller pump and so far it seems to handle towing in 100 degrees pretty well. Under those conditions my truck sees the high end of the last segment when I push it too hard and takes what seems forever to cool back down. The torque converter really ups the heat load. Best thing to do is slow down and kit out the OD. If that doesn't being it down I turn off the A/C and suffer .

 

Hmmm, i did put a termostat in here a few months ago, and it came from one of those el cheapo parts houses. I forgot about the Cummins only thermo warnings. Ill see what I can come up with and go from there

 

My fan clutch and thurm are form the chrys parts counter, the truck would swing wild ly from hot to clold before i replace the thurm and i did the fan clutch at the same time!
Now the only time i have a heating probem is when im pulling a long hill and the fan stops roaring long inought to get the temp up and then never gos back down form there.
I try and not get it that hot just becuse i have the "proan to crack head" and what to save my seft from going down that road!

Did thay have diff guages in the diff years? the reason i ask is the clock positiion of my guage would be from say....10 ta 2 o clock position! 10 being cold and 2 being

 

Now that could be because my '92 is the same as what is in the '93 FSM.

 

Hi boatnik, i'm an idea the guages is just the way you described

 

Don't beat yourself up so bad. I proof read these things over and over and still hardly ever get it right. Did you know that 10 out of 2 people in the USA are dislecKsic?