I have been in search of a hesitation under 2k rpms for a couple of months now. I finally bit the bullet and took my car to the dealer. They first called me and told me it was a loose negative battery terminal. I told them I would feel better if they gave me a different answer. A couple of hours later they called with a thermostat that is stuck open. The tech continued to say that this is a pretty common issue on these cars. They are going to call me back with a quote on the job.
Here is the dilemma. From what I have read this isn't a too bad DIY project, but BMW isn't %100 certain this will fix my problem. Should I let them fix it or try this one on my own?
DIY. If this doesn't solve the problem then take it to an Indy.
BTW my answer is from assuming that they are not going to charge you anything for checking the car out(which I doubt). If they already have everything out and just need to swap thermostats, I would just let them do it because you'll get charged labor anyway.
I just had my thermostat replaced (fault code 69). I had my indy mechanic replace it. Part is around $100.00. BMW standard labor calls for 4.5 hours for removal and replacement..
I guess I dont understand how a stuck open thermostat can trigger or cause engine hesitation at any RPM.
On mine, the symptoms were: Fault code 69. Engine takes a while to warm up.
__________________
Dan
Supersprint Headers, Tubi Rumore Plus exhaust, Dinan CAI, Defi Heads Up Display, Strong Strut front anti-sway bar, Powerchip 93 S/W, Euro Arm rest, Fikse Profil 5S Rims; Goodyear Eagle F1 GS-D3, Polk Audio Tweeters, Boston Acoustic Speakers, Integrated 60gig Video Ipod, HiDef DICE Radio iPod interface, Icelink, Rouge Engineering Short shifter, StopTech Big Brake Kit, TC Design rear sway bar brackets, HID 8000k fog lamps, 8000K low beams, Euro clear corner HID headlamps, Mark IV Nav, Lamin X films, Predator ICE LED AE, Valentine 1, M20 Blinder Anti Laser, TEC cup holder, All LED interior lights, LED footwell lights, LED trunk lights, Ultimate Cup Holders, Hella TC-400 Tire Pressure Monitor System, etc.
I just replaced my thermostat last night, as it was giving a SES light. It took four hours, only because I did it while the coolant was still hot (not scalding) and I removed the left engine bolt and couldn't find it for three of the hours. I finally found it, stuck in the chassis above the drain hole. Knowing about gravity, I didn't bother to look there.
The biggest PITA was: 1) removing the coolant temperature sensor without damaging it, because of 2) working around the VANOS thingy that's bolted onto the thermostat housing.
Thermostat was ~$32. Coolant was ~$24 (must drain and replace coolant if replacing thermostat). And remember to torque the attachment bolts of the thermostat housing at 10 Nm as they will easily break.
The job would have taken one hour if it weren't for the three hours of looking for that plug. Also (sorry, I'm rambling), the coolant plugs have blue loctite, so the cracking sound is normal.
Last cautionary tale--wear safety goggles. You have to remove a heat shield in order to access a plug. There is a lot of mud, dirt, and rocks suspended by the chasis and it seems to all come down when you relieve the heat shield.
I'm sure there's a DIY somewhere. If not, I can write one up.
The dealer is charging $90/hr. They said that they will charge even if this doesn't fix the problem because the thermostat is bad. They were going to charge me 1 hr labor to install a battery. I hope they didn't get offended when I laughed out loud. The dealer is 2 hrs away one way. I didn't really have time to drop it off in the first place. I am leaning towards letting them fix it simply for lack of free time. Besides, if I replace the thermostat and it doesn't fix the problem I will have to take it back to the dealer. The two closest certified mechanics happen to be BMW dealers in Asheville NC (2 hrs away) and Atlanta, GA (also 2 hrs away). I am hoping to get a free coffee mug out of the deal since they wouldn't work with me on a loaner car. Mafs were brand new, New plugs, new o2 sensors. The thermostat makes perfect sense to my problem. I just wanted to post the possible "solution" to my problem. I can't stand it when people have a problem and never post the fix.
BMW wanted $750 for the new thermostat installed. Needless to say I am making plans to pick my car up today. They wanted 6.5 hrs labor and $175 for the thermostat. I know the the thermostat is under the intake plenum...do I need any new gaskets or just new thermostat, gasket, and hose?
BTW, BMW is charging me $90 for diagnostics, which is think is very fair.
I told them I would feel better if they gave me a different answer. A couple of hours later they called with a thermostat that is stuck open. The tech continued to say that this is a pretty common issue on these cars. They are going to call me back with a quote on the job. 
Linear Mode
