That's both reassuring and disappointing. If it's the thermostat, why does it cool down when the engine is revved?

 

Possibly because the fan and the water pump are both going faster when you rev the motor. Which may indicate that they are both working correctly.

 

At idle you get pretty limited air flow, when flushing my cooling system post head gaskets I would run up to 197/201 at idle after a while. Blip the throttle and bring the revs up to 1250-1500 right back down to 188 in a few seconds. Leave it long enough fan speed increases,as the clutch locks up same effect

 

The idle/revving scenario is what I'm encountering. I can be idling to 203 and then increase the engine speed and the temperature drops to 188 right away. Is this normal or indicative of a possible issue?

Thank you!

 

@NVDiscovery Perfectly normal, at idle your water pump is running at your idle RPM as you increase RPM your water pump spins faster moving the coolant through the system faster getting a greater volume of water cooled. There is a upper limit because of course faster rpm also means a warmer engine.

How are your temps at about 2000 rpm while moving ?

 

At highway speeds (65mph) I typically see 188-190 maybe 194 on an upward grade. Not sure of my rpm at 65mph but probably under 2000.

Thank you!

 

This morning I bled the system and added enough water to overflow the bleed screw opening. At 65pmh I'm turning 2300 rpm and temperature was steady at 188. Coming off highway and sitting at light temps creep up to 203 and then drop to 188 within a half a mile of the light. I'm guessing that may be that my 5 year old (40k miles) radiator needs to be replaced? It looks pretty clean to me but who knows about the inside. Thoughts?

Thank you!

 

@NVDiscovery Could be the rad but that is not bad, mine will do the same thing. When I coast to light from highway speeds my temp drops to a low as 185ish, less load and the fan is still somewhat engaged. But come to stop at alight after a series shortish runs between light I get up to 203, the question is if you stay idling does the fan kick in and the temp drop ?

 

Yes, the fans kicks in but the temp only drops to 201 or so.

 

@NVDiscovery Well mine is doing the same it will idle for a 15 minutes and sit happily at 201 to 203. That is 3 degrees higher than before my head gasket job, but I am running a lighter weight oil right now. I am not going to worry about it, for now I will just monitor things.