M998 Fan cycling on/ off before reaching temp

[WAGNUM]

My fan sometimes randomly cycles on and off before the engine reaches full temp (mine is 220 deg dead nuts).


It has done this it at 120 deg, 160 deg, etc... It always works like it should when it hits 220 deg. Runs until it cools down, then shuts off. I've ordered a new temp sensor that goes on the water cross over so hopefully that will fix it.


My TCM seems to work, when the fan is on I can mash the throttle and the fan shuts off for 10 secs (thinks I'm fording) then kicks back on. Any thoughts?


Could it be thermostat related? Not opening and closing properly?

 

[Retiredwarhorses]

Got nothing to due with T-stat...the fan system is hydraulic and controlled by 24v's.
replacing the thermostatic switch is a good start...because that switch is what sends or cuts off the 24v to the TDM based on the temp. A little side note, not sure when your fan is engaging during the time before full temp, but if you make hard left and right turns to the steering stops at any time, it will engage the fan as well....those hard turns stop or most likely slows fluid flow just enough so that the fan clutch engages. I have also seen low PS fluid level cause erratic engagement...but at this point your hearing moaning from the PS pump as well...if it's already not Grenaded.

 

[papakb]

Good points Steve, and there's also the issue of snapping the steering pump shaft when hard stopping in a tight turn. This issue sounds like the temp switch in the crossover pipe.

Kurt

 

[kfrosty]

I agree with Steve. I had one of mine cutting on at 200 degrees instead of 215. I changed out the temp sending unit in the water cross over and now it's 215 degrees like it states in the TM.