fast idle when towing

[ichoplin]

I noticed a curious high idle while towing my 34' fifth wheel home from Georgia. When I would come to a stop, my truck would idle at 1000rpm. Seems like it would return to normal after a few stoplights. I let it idle at that rpm for several minutes at one rest stop and it didn't go down on its own.

The temp gauge ran at the second zero on the 200 for most of the trip. Could this be a measure to try to keep the fan spinning?

Speaking of my temp gauge, how much fluctuation is normal when the truck is pulling a load? My gauge never went below 200 and danced around the upper hash mark just before 245 several times. I didn't notice the gauge acting this way the last time I pulled.

Thanks,

Ian

 

[JamesStevens]

I am Canadian so I don't know how far 245 is but if the truck is running a little hot it will rev up to cool down

 

[CoastyAV8R]

I notice with mine that if I coast up to a light in neutral, the idle hangs around 900-1000 rpm then comes back down most of the time after I stop. My 04 truck did the exact same thing since it was new so I'm not too worried about it. I just put it in gear and just start to let the clutch out and it drops back to normal. It doesnt do it all the time, just once in a while and this is with the engine at the normal operating temps.

 

[JMarketos]

Must admit, I don't have experience towing large weight like you're doing, but have to say... sounds to me like your truck is running unusually hot. I have towed ~ 7K in 105F+ Texas heat, also in 90F+ through the hills in PA, and my temp gauge rarely got above the area of 180F (xx sorry, I mean 190, whatever is the normal thermostat point) (maybe occasionally a needle width higher). IMHO, readings in the area of 220F-230+F as you seem to be describing... warrant concern and further investigation.

 

[mymtnhauler]

I pull a 16,000# Goose neck all summer, and have not noticed this high idling! I must admit that I don't remember what temp it runs at, but I will remember too look this summer. If this is something that should be enabled, then it will be done!Oo.

 

[Andersonville]

Your truck is running too hot. Check the coolant,coolant level and look for leaks. I would replace the thermostat. Get a cummins thermostat. They are better quality. Your truck idled
high? Did the fan run fast? You could have a bad fan clutch too. It should have codes showing for these problems. Even pulling a big 5th wheel uphill,the temp should NEVER go above about 225 degrees and then only for a very short time.

 

[ichoplin]

Thanks for the replies.

I did have to add a gallon of coolant to the puke bottle. Seems like it's been low since the day I got it(Oct 09).

If I remember right, I can't check codes on this truck like I did on my 04, right? Do I need to have a code scanner plugged in?

Is there a way to physically check to see if the fan clutch is bad? I shook and spun the fan. It didn't have any wobble and it spun with resistance. I know this isn't the most scientific method.

The coolant I added was the Prestone Extended life. The bottle said it could be mixed w/ any color a/f? Did I mess up? I was in a pinch and this was all I could find. Should I flush the system now?

BTW, the truck has 71,000 miles.

Thanks, Ian

 

[ichoplin]

Andersonville, you recommend a Cummins brand t-stat, are they that much better? You wouldn't trust a Napa brand? Just wondering as it's Saturday and snowing here in Okla.
Ian

 

[rbattelle]

A sticking idle could be other problems.

Bad Connection.

Here's another thread which cross-references more materials.

Ryan

 

[ichoplin]

Thanks for the links Ryan. All very informative, but no one mentions the high temps that I'm seeing. Just today(temp in the 30's) I noticed a little "warm-up" on my gauge while going up a small hill. I was at approx 60mph, 2500rpm, unloaded and 5th gear. The gauge went from just below the middle mark, to almost in the second zero of the 200 mark.
My local dealer didn't have a t-stat in stock, so I bought a Napa one. I'll do some more searching on the t-stats before I install the non-Cummins one.
Ian

 

[ichoplin]

Well, I went ahead and put the Napa t-stat in. I read for a while on here and couldn't find anything saying not to use a t-stat from Napa.
I really couldn't get a decent test drive in b/c of the weather we're having. I may be pulling my 5th wheel tomorrow, so that will be the test.
Ian

 

[rscurtis]

I trust you're aware that by adding coolant to the overflow, it's going to take many heating and cooling cycles to get into the radiator. You can test your thermostat in a pot of water on a stove with a thermometer to verify if that was your problem. I would vote for the OEM part or a Cummins part over something that came from NAPA.

 

[CoastyAV8R]

You should be able to hear your fan when it turns on, it's pretty hard to miss the hum or it. Have you heard it come on? In all my experiences, it's pretty rare for it to come on even when we pulled our 5th wheel through the rockies I didn't hear it. Do you have an EGT gauge? I'm just curious because if you run the dog**** out of the truck with a heavy load without regards to EGT, I imagine you could get the truck to overheat. My fan would kick on when it gets a little bit above the mid-range mark but it would quickly cool down, getting it up to near the 245 mark is a pretty scary deal.

 

[jhenderson]

When my fan clutch went bad, I noticed my truck idled high. I was snow plowing at the time and had just pulled into my next account off the 2 lane. I had been running with the plow high and square which doesn't usually cause overheating. The truck was at about 1000rpm and 215 degrees. As soon as it dropped to 200 it idled down. I replaced the fan clutch and never had another problem.

 

[ichoplin]

I do have an egt gauge. I never let it get above 1100deg. I know these motors can handle more, but I still have a 2nd gen mindset.

I tested my old t-stat in a pot of boiling water. It seemed to be working properly. My rad and overflow bottle are both full.

As far as hearing the fan turn on and off, I can't say that I have heard it lately.

This week I'll get a new clutch fan.

Thanks again,

Ian

 

[Andersonville]

The Cummins thermostat is a better product and is made for the engine. 190 degree is all I have been able to find. Good Luck Grady

 

[CToney]

IF your fan clutch goes and they do go frequently. You will throw a code. P4083 improper fan speed. The fan clutch is expensive. I have had to change mine. It was shot at 100,000 miles. There is a wiring harness that goes to the fan clutch to engage it and monitor speed.

 

[MAshley]

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.

 

[S.Morris]

m

My fan speed has thrown a 0483 code for 2yrs now. Comes right b ack if you clear it. The fan however does seem to work properly?? Never runs warm..... but when running a/c fan comes on after every stop light and stays on until into 5th gear then kicks out and will stay out unless engine temp rises or you stop and a light again.



When not running a/c only locks up if engine temp rises.



steve

 

[JFought]

180* at Cummings I still occasionally hit 205 210 when i get on it, but it cools down in about 6 Sec's.

06 mega