Intermitent Over Heating

[CJLUJAN]

My truck seems to be over heating when going up a steep hill during hot weather 100+ temp. Temp seems to get to 210 (according to the Edge Monitor) butthen drops off on level ground or during the eve/night time. What can be causing this problem. any help would be appriciated.

 

[tkerrigan]

Not a problem at all, that is normal.

 

[CJLUJAN]

At whattemp should I get worried?

 

[matches]

On our latest trip I saw upwards around 235 on my autometer water temp guage. The stock guage was right of the center line, past about 1/8" or so. No problems, never boiled over, oil temp stayed in normal range. I was towing my fifth wheel in 100+ with a head wind, uphill! Other than low MPG, the truck performed great, trans temp never got too hot either. I think this is pretty normal, and I wouldn't worry. My 91. 5 gets hotter than that, but it also has evans coolant.

 

[sag2]

As long as the coolant does not boil, it's not too hot. In most cases this should be somewhere around 265 with 50/50 coolant and a proper pressure cap.

Now you don't want to run that hot all day long, but up to the point of boiling the engine parts are transferring heat to the coolant evenly, and the parts are designed to run that hot without fear of damage.

A much more comfortable number is probably below 235, and running at that temp for a few hours is not going to hurt anything. As always use common sense. If your just running down the highway and it's 235, something is wrong. On the other hand, if your pulling 18,000 up a 6% grade at 30 mph in 110 degrees, it's probably going to get hot. Also remember that more speed generally helps as it increases air flow through the radiator. So if the temp is high but stable, keep it moving. Also a trans converter unlocked (1st or 2nd gear) adds even more heat to the cooling system. Try to get to a speed and gear that gets the converter locked.

 

[mikeshauling]

You are probably fine, but if its the truck in your sig. then i would replace the thewrmostat and flush the radiator and put in some new fluid just to be safe and know thats not gonna be a problem. IMO

 

[sdgrahamca]

I had a similar problem with my 2006 5. 9 and found that the fan clutch was not engaging due to a dirty connector

 

[HBarlow]

210* towing up a grade is normal, routine, to be expected. If you're not towing it is probably still normal on a steep grade. I wouldn't spend a nickel looking at or "fixing" anything. More pedal means more fuel burned means more heat generated.

 

[Bill Stockard]

... Also a trans converter unlocked (1st or 2nd gear) adds even more heat to the cooling system. Try to get to a speed and gear that gets the converter locked.

The torque converter will lock while in 2nd gear on my stock 48RE at speeds above 20-25 MPH if it's manually shifted into 2nd gear.



Bill

 

[HBarlow]

The torque converter will lock while in 2nd gear on my stock 48RE at speeds above 20-25 MPH if it's manually shifted into 2nd gear.

Bill

My '06 w/48RE did also. It's handy if you're pulling a long slow speed grade w/heavy trailer in tow or easing down a slow speed steep grade using the exhaust brake.

 

[cerberusiam]

The torque converter will lock while in 2nd gear on my stock 48RE at speeds above 20-25 MPH if it's manually shifted into 2nd gear.



Bill

They will lock in 2nd but the program is not that aggressive. At low speeds and a lot of throttle they will lock late. Stop and go traffic and you generate and dump a LOT of heat into the trans and coolant before you ever get the TC to lock long enough to cool things.

 

[Bill Stockard]

They will lock in 2nd but the program is not that aggressive. At low speeds and a lot of throttle they will lock late. Stop and go traffic and you generate and dump a LOT of heat into the trans and coolant before you ever get the TC to lock long enough to cool things.

I never use the 2nd gear lock up feature in stop and go traffic since it's practically useless in that application. I only use the 2nd gear lockup feature when towing/hauling up steep grades with switchbacks, where due to many 20-30 MPH turns, I cannot hold the speed up enough to effectively use 3rd gear lockup. I travel highways like that in NM, CO, UT, and WY.



Bill