Weak heater...car also takes a LONG time to warm up.

[shrike071]

IMHO - I place very little stock in anything the PO said he/she did to the car before I owned it. To me, it sounds like a classically failed thermostat.

[Denton]

IMHO - I place very little stock in anything the PO said he/she did to the car before I owned it. To me, it sounds like a classically failed thermostat.

Gotcha. My car was a CPO car, so everything was done at Global Imports. I've got an Excel file of all of the service, but it's in Atlanta.

[BillionPa]

replaced thermostat 30000 miles ago... sounds like its due for a new one.

[brick8]

Mine takes about ten minutes to reach the middle line when it is really cold out (0-10 degrees F). Seems like forever when it is that cold. My volvo warms out in about 2 minutes. Plan on doing the thermostat asap.

[Denton]

Thanks for the advice guys.

What thermostat to order (how cold)? Do I order a TStat gasket as well?

[Alexlind123]

Thanks for the advice guys.

What thermostat to order (how cold)? Do I order a TStat gasket as well?

Whoever answer this question, could you answer it for the 535i engine as well?

[bigtisas]

Had the same problem. Car took a long time to warm up. Replaced the thermostat last month and solved the problem. I bought the t-stat from autohausaz.com and it came with a gasket.

The weak air blown problem could be the microfilter. If you haven't changed it for many years, do it.

[zhandax]

The 540i and (it looks like) the 535i have an O ring instead of a gasket for the thermostat Thermostat goes in the water pump, O ring goes on top of that, housing goes on top of that. O ring seals the housing. The 525i is a different design, but it appears to use an O ring also. Yes, replace the O ring. They are much cheaper than doing it twice. Biggest pain is draining some of the coolant. Here are the parts for a 525i: http://www.realoem.com/bmw/showparts...03&hg=11&fg=35

[Dash01]

Bingo on the 535i O-ring placement.

Before you install the new T-stat, drill a ~1/8" hole near its lip, and place it at the 12 O'clock position when back in its housing. This allows air to move past, and makes bleeding the cooling system much easier. Also, open the heater controls to max heat when bleeding, and park the car nose high.

[AutoXr]

My fan problem was similar when I got the car. Dug down in there and found the microfilter. It was clogged with snow! Cleaned it all out and airflow increased a bunch!