Do the diagnostic thing with the instrument cluster, see what the coolant temp actually is when warmed up. Do it on a cold day/night if possible, with city/highway driving. It should not dip below 79/80C once warmed up.
I got my parts from www.crownauto.com They are a BMW dealer, with decent prices. I think it was $80 for the thermostat, and $40 for the sealing ring, plus a few extra bucks for the o-rings, which you should definately buy. If you tear one, you'll be screwed if you didn't buy extras. I figured it was better to go with the BMW part than an unknown elsewhere, it's not a hard job to do, but not something I wanted to do twice.
Someone recomended vaseline on the o-rings when you put it all back together.
In 20-30 degree weather, I would only get up to 68-70C max, now I hit 79-80 no problem.
First, with all due respect, you can verify all you want, but you are incorrect (I'll give you the benefit of the doubt as you did not know the condition of my car).
My coolant wouldn't get up 78C and was hovering around 60. Coolant sensor realizes engine is cold, it uses more fuel and runs rich (to compensate for a colder engine). Refreshing the 78C thermostat was required (since the DME was reporting a failure of the thermostat).
I don't know about vaseline on o-rings. Can see a potential harm (oil-based solvent on oil-based solute), but don't think it would affect them.
lol, we're probably not on the same page, it was in reference to the OP's dealership diagnosis.
The dealer cleared the codes 3 different times and that is the code that kept reocurring. It also makes perfect sense to the condition of my car. I have already replaced the MAFS, O2 sensors, air filters, spark plugs, and I think thats it. I don't know what the actual code was, but they said the thermostat was definately bad. The M tech also said the car was not warming up to the correct operating temp. If this isn't the problem I have been troubleshooting, it is definately a problem that needs to be addressed.
But did the thermostat fix the hesitation problem ? (I've read the thread, but I don't think it was confirmed whether the thermostat fixed the hesitation).
Just put the thermostat in yesterday. It didn't fix the heistation problem. When the car is in 6th and pulling below 2k rpm's it surges/hesitates(does it all the time, but most noticable in 6th gear). My car does get up to running temp now. No codes are thrown. I am comparing my M5 to the way that my 540i pulls from low rpms. I am assuming that the M5 is supposed to be close to as smooth as the 540i, but I don't know for sure. I have only driven my one other M5 and that was at a driving school in Spartanburg, SC.
Just put the thermostat in yesterday. It didn't fix the heistation problem. When the car is in 6th and pulling below 2k rpm's it surges/hesitates(does it all the time, but most noticable in 6th gear). My car does get up to running temp now. No codes are thrown. I am comparing my M5 to the way that my 540i pulls from low rpms. I am assuming that the M5 is supposed to be close to as smooth as the 540i, but I don't know for sure. I have only driven my one other M5 and that was at a driving school in Spartanburg, SC.
I know this has been an ongoing problem. What mods do you have and what software are you running?
BTW, recent cold temps in Florida show that my tstat is also sticking open, but no surging issues.
Regards,
Jerry
__________________
'01 Black/caramel
Dinan Stage 3 suspension, SS jet coated headers, ESS SC kit, open brake ducts, Hamann front splitters, TEC cupholder, U.S.(Euro style) tilt/slide armrest, 6k HID fogs, 6k super white low beams, V1/Stealth1, dual head LI, 2.65 diff w/40% lockup/2x dynamic, compact spare, Euro trailer hitch, Mocal oil cooler, ACS type rear spoiler, Rogue custom SSK and tranny mounts, ST 355 BBK (fronts), BP sway bar brackets, Bluetooth retrofit
My car is bone stock besides the Magnaflow mufflers. When the tech at BMW drove my car he said that it drove normal and he didn't notice any problems. The only code that the car had was the stuck open thermostat. My driveway is kinda steep. When I "feather" the gas pedal while letting the clutch out the engine seems to sputter until I get the rpms up. A mechanic friend of mine drove the car and said it feels normal to him, but then he went on to say he is used to driving a jeep cherokee. I guess anything would feel good compared to that. I am about to give up and just live with it. I can't believe that no one else has had this problem.
Linear Mode
