Coolant Temp Bouncing Around

[jhillam]

My trusty Dragon 700 RMK had motor internals refreshed over the summer. I got it out today for first ride and coolant temps were bouncing around erratically (121F, 128F, 115F, 151F, etc). What gives? Is it bad temp probe, sticky thermostat, or electrical problem? All else seems fine and sled runs great.

 

[TRS]

My trusty Dragon 700 RMK had motor internals refreshed over the summer. I got it out today for first ride and coolant temps were bouncing around erratically (121F, 128F, 115F, 151F, etc). What gives? Is it bad temp probe, sticky thermostat, or electrical problem? All else seems fine and sled runs great.

Sounds like air in the system.

 

[XCaSSAULT]

Adding a little water wetter really helps also

 

[sled_guy]

By bouncing around do you mean like instantly bouncing around? Or over the coarse of a couple of minutes you see it bouncing around?

sled_guy

 

[sledfoot]

Replacing the temp sensor fixed mine. It was jumping all over and kept putting the ECU in failsafe mode so it ran like crap. But I would check the wiring harness first, especially around the jackshaft and steering to make sure it's not chaffing on anything.

 

[diamonddave]

Replacing the temp sensor fixed mine. It was jumping all over and kept putting the ECU in failsafe mode so it ran like crap. But I would check the wiring harness first, especially around the jackshaft and steering to make sure it's not chaffing on anything.

Agree. Sounds like a faulty connection, compromised wiring, or defective temp sensor if this is happening fast.

But like TRS stated, I'd also verify there's no air in the system.