rennteknik

I am posting this for educational value..

it seems when most thermostats fail they fail open.. well mine was sticking closed, and it appears to have been since I purchased the car earlier this year.

my oil temps sat on the 210 line since I had purchased the car.. water temp was always in the middle but straight up and down.

this was what I thought was normal.

I have a evolve tune

about two months ago I started getting some pinging when I accelerated hard, I thought it was a bad tank of gas.

filled up again and it continued.. switched stations and it persisted.. I was starting to wonder if i was getting 91 instead of 93.

then my oil temp started to move past the 210 mark about a month ago. two days after that the water temp gauge finally moved past "normal"

I parked the car and had my friend look at it. water pump was good, fan was good.. he said replace the thermostat.

when i finally replaced the thermostat temps all came back to normal, but I had pinched an oring, so it leaked..

2 attempts later and after pulling the plenum i was leak free and temps where rock solid.

using the functions in the cluster I get the coolant up to 83 degrees celsis and hold it unless I romp on it.. then I might see 85-86 briefly then back down to 83..

the oil temps sit to the left of 210 Fahrenheit and the car no longer pings on throttle tip in

the car is night and day different now. the evolve tune has really woken the car up.. I honestly really didn't notice it initially.. the car has been running hot sit I have owned it.

so if your oil temps seem a little high.. replace your thermostat.. it has made a huge difference in the way my car runs.

Casparado

My thermostat was sticking open, so I installed a new one. It seemed to be fine for a couple weeks, but then it started happening again! I doubt I got a brand new faulty thermostat. Anyone have any ideas on why my engine might be running cold occasionally? The SES light coming on sometimes is really starting to bother me, but every time I had the codes pulled it is the same thing. Also, the AC fan seems to be running when it shouldn't, if that helps anyone diagnose.

rennteknik

bad sensor?

jselig

Its these piece of s%-* thermostats. My 4 th one in 2 years just failed again after ~1month.

Im gonna try the E60 one. Totally different brand.

bimmerule

I know what you guys going thru, 3 t-stats in 2 yrs. Last one, I did DIY, so far so good.

mgdmb

p/n on the E60 t-stat? I'm getting ready to be on #3 in 1.5 years...

DouglasABaker

How are we diagnosing all these failed thermostats? What exactly are the symptoms you are all experiencing that leads you to this conclusion?

OP - did you put your t-stat in a pot of boiling water and watch it fail to open? If not, how do you know it failed closed?

rennteknik

did you read my post?

car was running hot, began to overheat..

water pump and fan clutch where good..

replaced thermostat and car runs cooler and all together better..

mgdmb

In my case my coolant gauge was reading too far to the left, and Test #7 confirmed this morning that the temp was running between 75C and 77C, after 15 minutes on the highway @ 80-ish.

The top and bottom radiator temp sensors are new. I'll boil the t-stat once it's out to confirm; then I'll see if I can't get some black powder and 'fix' the old t-stat...

Sailor24

Did you read his question?
First and foremost your answer does not answer his except to point out you have not diagnosed this correctly.
Do you know that there is a ring gasket inside the T-stat that will grab the t-stat when it is old and worn.
Have you replaced yours? It is called for every time the stat is replaced.
Have you removed the T-stat cover lubed the ring up and seen if the temp becomes normal?