Coolant temp spiking

[jonny d]

My coolant temp was spiking to 250+ this weekend. Any time my injector control pressure got above 18k, my coolant would start rising rapidly from the low 220's to over 250. As soon as the injector control pressure drops below 18k the coolant temp goes down just as fast as it went up. The exhaust temp did not spike, it stayed steady.

I was towing around 11k, and first it happened while going up 6٪ grade. But it also happened when I downshift to 5th to use my exhaust brake going down the grade.

Any ideas? I spent the rest of the trip driving by injector pressure to be on the safe side.

 

[GCroyle]

Nope, just a seat of the couch SWAG. Did you confirm the high temp at the T-stat housing with an IR Temp gun kinda tool?

 

[jonny d]

Nope, just a seat of the couch SWAG. Did you confirm the high temp at the T-stat housing with an IR Temp gun kinda tool?

No, I didn't have one with me. Because the EGT didn't spike, I was leaning towards an electrical problem, rather than a mechanical problem.

 

[GCroyle]

That was the idea by confirming it’s not an actual temp issue. I just grabbed a tool at my elbow, it was the temp gun.