I had a HD diesel mech replace both pumps, after much research here, and the truck runs great. We were careful to provide (and get) a replacement pump with the same number on it. Previously, the temp needle would run about a needle width below 180; now, with 5th wheel behind, it runs minimum of 200, and on hills would get to redline if I let it. I am familiar with all the usual causes of engine overheating, but is there anything that anyone knows that is unique to LP & VP replacement that could cause this? Thanks for the help!

 

Any time you are pulling a load your truck is going to run a little hotter. How hard are you pushing the engine while you are going over those hills? I don't think a LP & VP could cause this problem but I might be wrong. When was the last time you had your radiator flushed and refilled?

 

how many miles on the truck for starters?it could if they have the wronf timing key way in the injection pump,have you ever flushed out the radiators cooling fins on the out side?do you here the clutch fan come in on the hills when it is running hot?look at some of the old posts on the over heating and they should help you,good,luck

 

I'd change your t-stat right away just to make sure that's not the problem.

 

Thanks for the quick responses, guys! Yes, Pa, we were very careful about the timing key. I stopped at the top of the pass coming out of Haines, Alaska yesterday, and spun the fan by hand to see how much resistance there was when the engine was on the hot side of normal range. I just went out and spun it again, as it has sat for 24 hours, and I would say the amount of resistance is the same. Also, I used to be able to hear when that fan would kick in, and I haven't heard it recently, so perhaps that is the problem! Perhaps I will change the fan clutch, see how that works, and then see about changing the thermostat. Don't want to change too many things at once, don't ya know!