I know this has been somewhat discussed already, but it seems to go no where. I'm having this issue and have had it off and on for the last 2-3 years. After multiple relay changes, a Hydraulic pump replacement 6 months ago (problem has returned after 6 months on a warm spring day), now BMW corporate and dealer wants me to replace the SMG control unit (about another $1400). BMW corporate is refusing to admit there could be a problem inside the pump itself. They're now telling me if the control unit doesn't fix the problem, they want to replace my entire transmission? Problem is, I live in a very hot climate, inland in Southern California where 80degrees is on the cool side. Anyone else out there had this issue and have a successful "replacement" story? BMW NA says they know nothing about this issue and are not being of any help at all. They are refusing to honor the warranty on the pump, because they say now it's not the pump. Bottom line is, they were either wrong on their diagnosis of the pump in September, or are wrong about the diagnosis now (of the control unit).
Update on SMG transmission issue......... Well, I have to give credit to the people at BMW . Although it took 7 weeks and a lot of persistence, they replaced the control unit, only to have the problem come back within minutes. Instead of trying to replace the transmission (and likely have to eat that too), they decided to replace the hydraulic pump again.... They've done that and have "pushed the car to the limits temperature wise" and the problem has not come back again. FINALLY!!!!!!!!! That said, I still think there is an inherent problem with the pump and hot weather, but we'll see soon enough. It's coming into summer and it gets about as hot as it gets where I live. We'll know soon enough if the part inside the pump fails again, or if it was just a bad pump.....again. At least BMW finally ponied up and did the right thing.
E46 M3 SMG Pump I have an 2002 E46 M3 and only recently had the trans pop out of gear when extremely hot and stuck in traffic. Its frequency has increased although so has the hot weather. Check engine and SMG gear illuminate when this happens and sometimes stay on for a day/night and sometimes go off. The dealer says it is the pump and wants $3500. The dealer says that their GT1 diagnostic machine shows the pump loosing pressure and that it is supposed to be at 60PSI all the time and mine drops. Does temperature affect pressure? I do not want to experiment with $3500 parts any suggestions? Has anyone gotten anywhere with BMW NA on this issue? Should I risk putting a used on in, or go with new? Has anyone ever torn a pump down and repaired it? On various forums I have heard HCU temp sensor etc but that thread seemed to dead end. Any help in the Chicago area would be appreciated. Thanks, Darren Spiegel dspiegel26@hotmail.com
Heat for sure is a factor I have several customers with SMG tranmsmissions that only have issues at the track and then only with high temperatures. On some of the cars we have removed the aerodynamic under tray to facilitate better cooling with some success.That said some cars have no problems at the same tracks and one would think the same temperatures. So this temperature sensor maybe a place to investigate.
Owning an SMG and a 6 spd personally - and working on several customers cars - heat is a factor- If you are having this happen ever so often/intermittently in really hot weather - install a new smg temp sensor part # 13-62-1-709-966 In addition I change my SMG pump relay one a year as a maintainance item - this relay works very hard to supply proper power to the SMG unit. On the flip side if your unit pops out of gear consistently- your SMG unit mostly likely will need to be replaced. Frequent fluid changes help alot- my SMG unit has 130k - redline DTF4- changed every 15k miles-neer had to change temp sensor oon my car- inaddition this fluid helps these transmission work smoother and more efficient in the cold months. If you have a manual car use this fluid you will not believe how easy the shift to second in the winter will be. The system is not to complicated if diagnosed properly when symtoms occur.
