Engine temp started to climb during last trip

[Dean E]

Been a while since I posted anything here but I wanted to get some input from my last trip with my LMM. I was pulling my enclosed 7x12ft trailer with my bike inside. No real weight but the enclosed trailer pulls like you are dragging a 15ft parachute behind you. I was in the middle of a 900 mile day and just wanted to eat up some miles so I bumped the speed up to 75 mph, normally I stay at 70 to 72 pulling the trailers since it does make a big difference in the MPG. Just east of Denver with a slight headwind and the outside temps were showing about 98F. The engine temp normally is rock solid at 210F. After about 10 minutes the temp started to climb a bit. Maybe 220-225F. I backed off the speed and the temp came back down. I changed the thermostat and coolant a couple years ago. When I got home I washed the truck and spent quite a bit of time flushing water thru the radiator to make sure there were no bugs building up in the radiator fins. Really did not seem too bad. Was this pushing too hard for the heat of that day? Has anyone else seen something similar? Dean

I will say adding the S&B 62 gallon fuel tank was one of the best decisions I made on this truck! D

 

[2004LB7]

Sounds like it's time to pull the coolant stack out and give it a good wash. Hard to wash out the debris when it's in the truck. Getting water to go through the radiator when you have the AC condenser in the way

May also want to check / replace the fan clutch

 

[Dean E]

I would not think a fan clutch would be doing much at 75 mph. The fan would be a definite player at issues around town or in traffic at lower speeds. As I got closer to Nebraska the outside temp lowered to 92. I tried going 75mph again and had no further issues. I was thinking I just pushing too hard for the temps of the day and wanted to see if anyone else had ever seen something similar. Dean

 

[Dozerboy]

Fan still plays a roll even at those speeds. You should of seen the temp drop when it engaged. If it didn't, it either isn't engaging all the way or you're cooling stack needs to be cleaned.

East of Denver is kind of down hill. I'm surprised you had issues their but didn't in NE.

 

[lutzjk913]

How many miles on the truck?

 

[Dean E]

211,000 well loved miles. D

 

[pl_silverado]

I had that issue on a hot day uphill, kinda in between gears lugging the engine cause of traffic.

And it wasn’t the cooling stack as I just replaced it all.

Hasn’t done it since. This was running a tow tune. Since then I’ve towed strictly on the HOT tune and never had temps climb like that ever again.

 

[Dean E]

I had that issue on a hot day uphill, kinda in between gears lugging the engine cause of traffic.

And it wasn’t the cooling stack as I just replaced it all.

Hasn’t done it since. This was running a tow tune. Since then I’ve towed strictly on the HOT tune and never had temps climb like that ever again.

You may have something there. I have a Gearbox Z tune with a 70 hp option that the engine does have. If I was towing a really heavy load I would that that tune off but this was just a hot day with just the drag of the enclosed trailer. I’m sure taking the 70 hp tune off would have changed the temp readings. Dean

 

[Ron Nielson]

Try pulling in 5th gear. You will get the same mileage, but a little more power and driveability.