*SOLVED* Soft Fail Thermostat?

[andrewwynn]

Originally Posted by Overboost

I ran a couple of errands this afternoon and the temp never dropped where it was this morning on the highway but with the needle straight up noon, Torque Pro reporting 87 to 88C. I will have to wait until tomorrow morning to run it to check the readings where the needle has been running on the highway.

great you have torque working that's the best way to verify; watch torque while initially heating up; the temp fake gauge will 'snap' to noon when it gets to something like 65C or so i forget what it's set to (with the right tools can be re-programed to non-stupid; sadly i don't have those tools).

When mine soft-failed I would get full temp and not overheat but when ambient was very cold the coolant temp would never get over 60C so i could tell something was wrong (in addition to that when really cold (like -10C), i would get no cabin heat; i had 2 or 3 trips to/from chicago where i had to stop for 5 minutes to let the engine warm up so i could get heat out of the dash to complete my trip.

The t-stat had a soft-fail where it wouldn't close off completely, it would open just fine to prevent overheat, but was likely never over 70C for months, i just didn't know because of the moronic non-gauge 'idiot needle' on the dash. Now i check time-to-time to make sure the temp is normal suing dash command (my version of torque). I like the interfaces in dash command and some fun things like automatic 0-60 and quarter mile times as well as instantaneous horsepower.

If you have a soft-fail open t-stat you won't achieve full operational temp when it's cold ambient, but when ambient is not that cold you will. I'm curious about the heater valve, and that's a good test anyhow to make sure it's working (that the heater hose should be cool not hot when no demand for heat).

Another low-heat situation is if coolant is low; apparently no indicator on 01 e53 even though the coolant reservoir has the sensor it's not hooked up; my reservoir recently sprung a leak and it took 'too long' to get cabin heat even though dash command reported coolant temp was fine. quick check on level and it was 2L low; topped it off and heat came back immediately i didn't figure out for a week what was the source of the low coolant.