Thermostat replacement - stuck open

alecu · #1 12-28-2013, 02:04 PM

Hello,
I have 160K and this winter I noticed the engine temp dropping while driving on the freeway at under 55 degrees. I had it scanned with DIS and there was also an error code for thermostat jammed open.

The previous did the cooling system at around 120K. As far as I can tell, all the other components seem to be fine, but the thermostat needs to be changed. I was hoping to wait and do the cooling system again around 200K.

The questions is:
Can you remove the thermostat without taking the pulley off the water pump. Is there enough clearance to get to the screws of the thermostat without removing that pulley?
Because if I have to take that pulley off, well, I might as well do the whole system again, but if not, I will do just the thermostat. I just need to know from someone who did this job to know which parts to order.

Also, is there a big danger of driving with the engine temp not in the "middle" while cold outside? The engine temp will go to the first white line and go back to the middle once I do city driving. Once the outside temp goes around 55 - 60, the engine temp will stay in the middle on the freeway also.

tmv · #2 12-28-2013, 02:31 PM

I did it on my old 01 3.0. No need to remove the WP.
Let me know if you need help, Alex.
Driving with open Tstat, your engine will never get warm up. There will be more wear than normal. Also the mpg will go down to.

alecu · #3 12-28-2013, 02:35 PM

TMV, how's your schedule next week?
Not for the thermostat

Just to meet real quick. We live so close and never met.

tmv · #4 12-28-2013, 02:37 PM

I'm usually free on Saturday.

alecu · #5 12-28-2013, 03:14 PM

Ok. Same phone number? I'll call u next Friday.

In the meantime, is there any big danger of driving with the engine running a little cooler until I can get to replacing this thing? I know it might use more gas and it could affect the cats, but is that for longer periods of time, or even short periods can do some damage?

tmv · #6 12-29-2013, 01:07 PM

I would have it taken care of as soon as you can. A few days to a week should not be too bad. I drove the old 3.0 with open Tstat for about a month before I took care of it.
Same phone number, Alex.

alecu · #7 12-30-2013, 10:20 PM

Does anyone know at what temp the engine turns off the "cold start map"?
I checked my coolant temp and it's at about 60 celsius when it's at the first white line due to the thermostat stuck open and I probably won't get around to it until next week or so.

I'm wondering if at this temperature the engine is still putting more gas in the mix until it reaches 90 or it's only to a certain temp.

This is probably good info for all those who are running around with a thermostat stuck open.

bmwman528e · #8 12-31-2013, 06:43 PM

Mine is stuck open. Ill let you know how much it sucks to replace. Ill be doing mine on Saturday.

alecu · #9 12-31-2013, 06:48 PM

It shouldn't be way too hard. You have to remove the shroud and fan. According to TMV, you don't have to remove the water pump.

The only thing that I'm afraid of just doing the thermostat by itself is that the old connections at the hoses sometimes don't fit just right.

Let me know how yours goes please.