ISX Cooling Problems

Oxbow

Well-known member
A friend of min recently purchased an 05 Pete heavy haul tractor that has an ISX 550 in it. He has noticed that the coolant temperature runs real hot (like 210) and engine oil temperature will get up to 250 when working hard and then stay that hot despite the coolant temperature coming down. This may be an inaccuracy in the gauge, but if not then there is reason for concern I think. He nor I have previous experience with that engine. He has ordered 180 thermostats for it, but I cautioned that that may cause other issues as the ecm monitors and adjusts according to "thinking" that it has higher temp setting thermostats.

Anyway, 2005 should not have egr/dpf problems, so what is the normal thermostat/fan settings on those engines, and can one get away with replacing the thermostats with a lower opening temperature?

Thanks
 

Truck Shop

Well-known member
Not sure on the 05's but the 07's we had, had a thermostat in the oil cooler. We had alot of trouble with high oil and water temps because of them.
Out of the nine T800's at least seven suffered that issue. I would check with KW or Cummins to see if it has that same set up.

Truck Shop
 

Truck Shop

Well-known member
I forgot to answer the question on the coolant stats. Those are set up with 195* stats the fan switch is probably 200*.

Truck Shop
 

Oxbow

Well-known member
Thank you Truck Shop, I was not aware of the oil cooler thermostat; I'll mention that to my friend as that could be the problem.

Thanks!
 

Goodysnap

Well-known member
210 is not high for coolant temp. Fan on temp should be around that though and anything that keeps climbing above 220 with the fan on should be looked into. Ditto Truck Shop on the oil thermostat and check to make sure your gauges follow the ecm monitor within a few degrees. Normally under load the oil temp will ride 10 or so degrees warmer that coolant temp.
 

Oxbow

Well-known member
210 is not high for coolant temp. Fan on temp should be around that though and anything that keeps climbing above 220 with the fan on should be looked into. Ditto Truck Shop on the oil thermostat and check to make sure your gauges follow the ecm monitor within a few degrees. Normally under load the oil temp will ride 10 or so degrees warmer that coolant temp.
Thank you!
 
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