I had the same problem with heat comming back from utah towing my 30ft goose neck with 2 samurais and 3 quads on it. the engine and trans was over heating at the same time. and could only tow in 3rd for it not to overheat. when i got back i found out my lift pump was bad 5psi on idle 0 at wot. did not have a fuel gauge in the truck i do now. solved all my over heating problems towing since. didnt have enough fuel engine struggling. tow the same load almost everyweekend. no problems since.

00 reg cab ctd 4x4, 410s
5in stacks aero turbine, bd x pulse 50hp inj, bhaf
bd valvebody, torqloc, perfect shift converter, amsoil, 20"x17" trans cooler from f 750 with an allison. she runs cold.
gauges

 

Sounds almost as if your centrifigal clutch is gone. The one on the fan that is. You should hear what sounds like a jet engins taking off when the temp starts to get up. The fan should start to kick in real hard and make a roaring sound which is an indication of it working properly. You can turn onthe AC during real hot days and get the same effect. If this does not happen then the fan clutch is shoot. You may be able to check the codes and see if you have one also.

 

How do you test for the fan clutch to see if it is shot other than not hearing it turn on. I don't know what it cost but it sounds expensive. I'm going to change my t-stat first.

 

That's a good question Slug, how can you test it other than hearing it. I can hear the turbo when it kicks in, sounds like a freight train. Just can't hear the defference with the fan. One mechanic I took the truck too, took an old radiator hose and tried to stop the fan from turning, he said the clutch was fine!!!

I am leaning more towards the fan clutch because there dosen't seem to be any drifference in the fan speed from when I start the truck to the speed of the fan when I'm overheating.

I'm going to print out all these replies and take the to my mechanic and see if he knows what the heck we're talking about.

The cost of replacing a fan clutch is a h--- of a lot less than replacing an engine!!!!

 

On testing the fan clutch......cut out a piece of cardboard, slide it in front of your radiator, start the truck up and run it at 2000 rpm. I use a spot out back of the shop as it's usually ungodly hot, and no wind. Do this test with the A/C OFF!! With the cardboard in place the condensor won't cool down from air flow. Usually about 3/4 on the gauge you WILL hear the fan clutch engage and even with the card board in place will pull the needle down some.

 

that was the problem with my 98 when it was 1 year old. I couldn't pull my 22' 5'r with out overheating.
The dealer Mech hooked up the diagnostic and went for a spin, came back and they replaced the clutch and thermostat..no problems since.
I think he said the clutch kicks in at 190 degrees so you won't normally hear it unless the engine is getting hot.

 

Ok you said that you replaced the thermostat. Which one did you put in? For towing you should have the 180 degree thermostat from Cummins, pn 3967195. This will make a big difference and may be the whole problem.

It is a 1999 and the fan clutch has to be worn. Go to Advanced or the like and the fan clutch is only like $69 and works real well.

I pull 30k gross regularly and never go over the mid mark on the gage.... ever. That is with the stock radiator, air on full, high humidity.

What was said about the radiator sucking up grease from the blowby of the breather tube. If you dont have an extention on it the radiator has a grease buildup on it. I was shocked the first time my radiator came out. If you want to be sure, pull it and clean it off. You can spray wash detergent on it and let it soak, then hose if off from the back. Then do it again till you see pretty clean alumimum. Then put an extention on the breather to keep it from happening again. Water through the back of the radiator in the truck will not even touch it.

If your system is in good shape your radiator will easily handle 350 hp. Probably more, but that I know.

I would guess your fan clutch though, because you said it takes so long to cool off. It should come right down with the air going through it.

 

I agree with the fan clutch not operating. A hose in the fan blades is not a real test and a good way to break the blade to hub connection.

Another thought, when you tow in the hills do you use the O/D lockout button?
If you let it shift out of O/D and run in third without the TC clutch locked it will get real toasty and the heat exchanger alongside the engine block will really force the engine heat to climb.

 

Thanks for all your help and suggestions. One last question from me. Is the fan clutch easy enough to replace? No special tools?

 

PITA is what it is. You may need to modify a wrench to get at the bolts but it is doable by the average backyard mechanic.
Did you have the codes checked yet??? Have that done at your local AutoZone for free, it may help point you in the right direction. Let us know th outcome

 

the big nut is left hand threaded. A large adjustable will fit if you remove one of the 13mm fan blade bolts. You can use a big pair of pumps to hold the pully. Will scratch it up but you can paint it black again and don't need a wrench to put it back on, it will tighten. Or just tighten it without holding the pully.

 

At the shop we would take a long piece of cardboard, BOX CARDBOARD not the thin flimsy stuff,and fold it in half, then CAREFULLY have one person stick one end of the cardboard into the fan This is where LONG comes into play,
And press against the fan blade holding it trying to not let it spin, Then another person ,Preferably someone you trust Ha Ha ,start the engine
THIS SHOULD BE DONE WHEN THE ENGINE IS ALREADY HOT, if the clutch is bad the cardboard will prevent the fan from spinning, if the fan clutch is good it will pass right passed the cardboard with no problem,DO NOT repeat DO NOT USE ANYTHING ELSE (your hand example) to restrain the fan.We have used this method many years SAFELY and found lotts of defective Fan clutches, and almost always if you see any greasy spotts in the center if the fan clutch This indicates that the fluid in the clutch is leaking and therfore should be replaced. BE CAREFUL if you wish to try this.

98, 24v, Ram 3500, SB Con O Fe Clutch, New NV4500 5 spd trans w all spline shaft, Edge Ez, all Iss Pro Gauges ,F.A.S.S, Air Raid Mass Air Flo Filter,Mod Air Box, L.E.D tail lamps.Jake brake, Western Hauler bed, 40gal aux fuel tank, low profile Polished aluminum tool box,25k Air Ride 5th wheel hitch,4" out pipe,Sirius satt radio,backup camera w 5"color monitor,freeze you out a/c and 3000 watts of Alpine Stereo.(Oh.... and ear plugs)and pulls a 42' Mobile Scout 412 SUT containing(Not at the same time) 02 Honda TRX250X,99 Yamaha 350 Warrior,86Honda TRX250R,88 Honda TRX250R,97 Kawasaki KLF400 4x4 Bayou and a Dog. Giddy up! (first VP still hangin in there,On F.A.S.S. after lp departed the scene 4/ 05 *RIP*).131,000Miles & Going!

 

Sounds like a real good way to lose some fingers. I lost one in a belt, I don't screw with belts. It's a '99, its warn out, change it.

 

And if you want a little more cooling, pick up a fan for a 98, the blades are wider.

 

OK guys, I went out this morning and stuck some cardboard in front of my radiator. Ran the engine at 2000 rpm. The temp gauge got up to about 200 degrees in about 8 minuts and I could not hear any difference in the sound of the motor. I could not hear the fan kicking in.

Here is what I could tell: Several times it sounded like the fan was either hitting something or gears stripping, didn't last long, just for a second or two each time. While holding the rpm at 2000, there would be a click and the rpm's would drop 125 rpm's for no more than 2/3 seconds. The sound of the motor did change during these drops but not the fan.

What do you make of that???????????????????

The 1998 fan sounds like it might be a good idea.