Isuzu NPR cooling problem,need help

[Thomas C]

My work truck has cooling issues. Does anyone here have experience with Isuzu NPR trucks. On the open road it runs cool,but in town it wants to get hot, the gage pegs hot.
I just replaced the thermostat today and that does not seem to be the problem.
It is a 91 Isuzu NPR Diesel turbo. It has sensors above and below the thermostat. I have worked on gas engines but this is my first diesel motor.
Any help would be appreciated. Thank you.

[chris francis]

Originally Posted by Thomas C

My work truck has cooling issues. Does anyone here have experience with Isuzu NPR trucks. On the open road it runs cool,but in town it wants to get hot, the gage pegs hot.
I just replaced the thermostat today and that does not seem to be the problem.
It is a 91 Isuzu NPR Diesel turbo. It has sensors above and below the thermostat. I have worked on gas engines but this is my first diesel motor.
Any help would be appreciated. Thank you.

I do not know much about engines but are you talking about the cooling system check your fans I had small car do the same thing as your truck it was fan problem on open road it had plent of air but in stop and go traffic it would over heat becuase the cooling fan was not working.

[PWkid]

You do not want to run a diesel engine hot for very long.

[jetstream1]

Maybe water pump starting to go bad or water is leaking from weep hole
Or heater core..Crack hose or a pin hole some where
maybe it needs a god ole flush.hope this helps a bit

[MichiganPowerWashing.com]

Yup ... first thing to check - cooling fans . Good luck

Originally Posted by chris francis

I do not know much about engines but are you talking about the cooling system check your fans I had small car do the same thing as your truck it was fan problem on open road it had plent of air but in stop and go traffic it would over heat becuase the cooling fan was not working.