Is my coolant thermostat starting to go?

[msan]

So I have an Awron gauge and I can see coolant temp in relation to oil temps. When I start the car (cold start) What I see is coolant temps climbs up fairly quickly to about 56 degrees C. While oil temp stays stuck around 31/32 degrees C.

After coolant reaches 56 C the oil temp slowly catches up and they (oil and coolant) are the same temp at 65 C. And then oil passes coolant temp and stays about 10 degrees C hotter than the coolant. Example oil 82 coolant 72 and later oil 88 and coolant 77.

It seems like the thermostat opens up around 56 C but that seems too low and maybe should stay closed longer until maybe 70+ C?

Thanks in advance!

[pbonsalb]

As late model coolant thermostats go, the factory spec for the S65 is on the cold end of the range.

[nurburgracer]

Originally Posted by msan

So I have an Awron gauge and I can see coolant temp in relation to oil temps. When I start the car (cold start) What I see is coolant temps climbs up fairly quickly to about 56 degrees C. While oil temp stays stuck around 31/32 degrees C.

After coolant reaches 56 C the oil temp slowly catches up and they (oil and coolant) are the same temp at 65 C. And then oil passes coolant temp and stays about 10 degrees C hotter than the coolant. Example oil 82 coolant 72 and later oil 88 and coolant 77.

It seems like the thermostat opens up around 56 C but that seems too low and maybe should stay closed longer until maybe 70+ C?

Thanks in advance!

It sounds like your thermostat has gone already. Do you see your oil temps go up (towards 100C) when you stop - and then down to like 80 when you are travelling at highway speeds?

I had a smiliar problem recently, couldnt really see what the coolant temp was doing but the oil temp took forever to get to 100 and went down when traveling faster.

The OEM thermostat is set to open at 79C.

[Redd]

My coolant stat (which was changed couple years back) quickly goes up to 81 degC and stays there. Oil temp slowly catches up. Yours sounds like it's already stuck in an open position.

[akkando]

Originally Posted by nurburgracer

It sounds like your thermostat has gone already. Do you see your oil temps go up (towards 100C) when you stop - and then down to like 80 when you are travelling at highway speeds?

I had a smiliar problem recently, couldnt really see what the coolant temp was doing but the oil temp took forever to get to 100 and went down when traveling faster.

The OEM thermostat is set to open at 79C.

Mine gets to like 90c then won't generally go higher unless I start driving at higher rpm, get into stop and go traffic or just idle, or gets very hot outside.

Definitely takes a long time to get to 90c or so at highway speeds.

Not sure if this indicates thermostat is stuck open.