Isuzu NPR Diesel running hot

Message Title: Message Text:  http  https  ftp  mail    hr     highlight   LI   Quote  Select Emotion SmileWinkSadEmbarrasmentDisgustedBig GrinMadShockedTongueCoolFrownConfused [q]The first thing that comes to mind is maybe the fan clutch in not operating properly or falling behind at higher speeds where the engine is running at a higher RPM (and where the cooling system is needed most importantly). I would say check the fan clutch and how is the condition of the radiator? Is it the original radiator and has the coolant been flushed at the right intervals over its operating life? The radiator may be plugged up if it's old. When was the last time the water pump was replaced or is it the original? Another thing you could do is pressure test the cooling system if you have the pressure testing tool with the hand pump and built in pressure guage. Pressure test it to the max pressure measured in PSI that's stated on the radiator cap to see if you have any coolant leaks in your engine bay. Also, did you test the existing thermostat to see if it is sticking and not opening at the right temperature? The best test to do on it would be to put it in a stove pot with the water level higher then the thermostat's height measurement and heat it up to see if the thermostat opens at its recommended temperature. If it doesn't then the thermostat plainly needs to be replaced with a new unit. I'd suggest going to an Isuzu commercial dealership to buy that part at least if it's bad. Being that you have a 1993 NPR it probably won't be too bad as far as a price on a new replacement thermostat. And I wouldn't recommend running the engine too long without a thermostat as it's not going to solve or make finding the problem come about. Good luck and let us know what the issue is.[/q]

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