fast idle when towing

[rbattelle]

I agree it takes a lot for my temps to go past 200... like a big hill pulling 14,000 lbs and even then it barley hits it.

I've found it's easy for me to make the temperature rise unloaded.



The center mark on the gauge is about 196°F. I've seen as high as 198°F on a long pull up a decent grade during hot weather (but running empty).



I've always assumed that if I were pulling 7 tons or so I'd easily see 210°F in the same conditions. But maybe I'm wrong.



Ryan

 

[ichoplin]

I just finished putting on a new fan clutch. Haven't driven it yet.

This morning(w/ the old fan clutch) I was driving to work completely empty and the needle went a hair over the halfway mark then came back down. I'll do the same route again in the morning and I'll definitely be keeping a close eye on the gauge. I'll update.

Thanks,

Ian

 

[ichoplin]

Definite improvement. Yesterday morning on the way to work, my temp gauge went above the halfway mark. This morning, it didn't even come close even with warmer temps. This afternoon, it was around 70deg and my gauge stayed below the halfway hash mark. The real test will be with my fifth wheel in a couple of days. Thanks again

Ian

 

[rbattelle]

I just remembered, there's a test in the service manual for the fan clutch. Grab the blades and give it a spin. If it rotates more than 5 revolutions, it's bad.

I know when mine was new it would rotate less than 1 revolution before coming to rest. I haven't checked it in years.

Ryan

 

[ichoplin]

I think my optimism may have clouded reality.

I just got home from a 200 mile trip, all interstate. Cruising down a turnpike here in Okla(speed limit 75mph), my gauge was over the halfway mark. Even after I got home and went through town, my gauge stayed above halfway.

The pics show that the egt's aren't too high and where exactly my gauge is.

Could my gauge be weird?

So far I've added 1gal of coolant, changed the thermostat, and changed the fan clutch. Now, I'm at a loss.

Thanks,

Ian

 

[wcjp]

I think there's a factory hose clamp that could come loose for the coolant. I think it was near the back of the engine near the firewall slightly toward the passenger side. I remember checking mine a few years ago. Mine was tight. Others reported it was loose from the factory.



Have you verified the temps with an infrared heat gun? Home Depot sells a Ryobi version for $29. I've been Offroadin' with friends who had overheat conditions. Most were bad sending units. A few have been correct high heat temps. One we immediately isolated to a bad radiator.



I use my heat gun to test wheel/brakes/bearings while towing. I typically test all wheels/brakes/bearings every other fillup when towing. I've also helped others identify problems with their trailer bearings. Very handy tool.

 

[ichoplin]

I was planning on getting an infared thermometer this weekend to check actual temps. I did notice a little drip from the hose going to the overflow tank. I put a hose clamp on it, but there was no change.

My next try was going to be to pull the radiator out and give it a good cleaning. On my 02, I had to do this b/c of the dreaded blow-by bottle. My rad looks clean enough from the top.

Ian

 

[JamesStevens]

If your rad is clean I would say bad guage, keep us posted

 

[PFlory]

I've towed my 5er through the Tennessee mountains last summer in the 90* range and never saw the temp go above 215*. I've got the Banks monitor set to de-fuel at anything above 235* temp, and 1300*EGT, but have never seen anything close to that when towing my rig.

 

[HBarlow]

The photo you displayed showing the temp gauge a little to the right of the center mark while towing a large and heavy fifth wheel trailer has been normal in my experience. 205* to 210* is exactly where the temp gauge has always resided on my my previous '01, and '06, and now my '08 Dodge-Cummins.

But I've never had one move the temp gauge over to 235* except my old '01 would approach that when the radiator fins were blocked with crankcase vented oil film and road dirt. As we all know, those Gen II 24 valve trucks require periodic radiator removal and pressure washing if the crankcase vent line is not moved.

Perhaps your fan clutch was bad causing the rise to 235* and that extreme is now corrected. Towing at 205* - 210* is normal.

On edit: I would not use a thermostat other than a Cummins/Fleetguard product. Thermostats of other brands may have different opening sizes or other differences that restrict coolant flow or improve coolant flow. Either can cause heating problems.

 

[ichoplin]

Forgot to mention in the post with the photos, I was completely empty when I took those. Just the truck and me.

The trip before all this started, I had no heating issues at all. In fact, on my way out to Ga I ran harder than on the return trip. The only thing I changed between pulls was a new Wix air filter and a Baldwin fuel filter, that's it. I'm off to get a I/R therm. this morning, so hopefully I'll be able to rule out the gauge. Thanks for all the replies.

Ian

 

[RVTRKN]

I couldn't find my manual, but I believe there is an air bleed fitting for the coolant system when filling. Maybe there is an air gap causing it, after you added the coolant. BTW, I would flush the system and add the proper coolant with the proper ratio to water. Mixing the two doesn't seem like a good idea, unless its an emergency. Also, I would pressure wash the radiator, and related equipment, spray on a cleaner prior to the wash.

 

[ichoplin]

My gauge is fairly accurate according to an I/R thermometer. Got readings of around 220deg with the needle just over the halfway mark on the gauge.

I'll be flushing the radiator this afternoon.

After this, the only thing not messed with will be the water pump. I've never heard of a water pump going out slowly. It's been my experience that when they're bad, they just GO bad and puke water everywhere. Anyone had a water pump malfunction without it spewing coolant?

Ian

 

[ichoplin]

Just got back from a test drive after flushing my rad. The temp gauge didn't go over the halfway mark, but it went to it and kind of hung out there.

I'll know more this evening as I have to drive 200 miles back to where I'm working. Wish me luck.

Ian

 

[ichoplin]

What about a faulty radiator cap? Could that cause my symptoms?

Just trying to cover all my bases.

I did drive it 200 miles last nite and it didn't get AS hot, but it still was at the halfway mark. This weekend I'm planning on pulling and washing the rad. I may even throw a new water pump on while I'm at it.

Ian

 

[rscurtis]

If you do more than one repair at a time, you won't really know what the problem was.

 

[ichoplin]

Check this out! I may have finally found my problem. This radiator is more clogged than my 02 at 150,000 miles.

I'm telling myself that the fan clutch wasn't wasted money b/c I definitely heard it a lot more while pulling my fifth wheel than before.

Thanks for all the replies and I will update if cleaning this thing doesn't help.

Ian

 

[RVTRKN]

If its possible pressure wash it from the fan side of the radiator so the dirt doesn't get trapped inside. When I wash a condenser to an air conditioner, I always wash from the inside out if possible. Be careful when using a pressure washer not to damage any fins.

 

[ichoplin]

I removed the rad to pressure wash it. My wife asked me if I was a pro at this now since she remembered me having to do the same on my 02Ram.

I've only had this truck since Oct, so it is hard to say what its history is. I can only guess what all that crud consisted of.

I bet I spent 45 minutes with my pressure washer and two cans of degreaser to get it clean.

Ian

 

[rbattelle]

So did that do it? Is it all better?

Makes me want to go check mine...

Ryan