Hello all, I have a 1994 740iL with ~105000 miles. Lately the transmission has been giving me problems. When I go to take off it feels as if the car isn't going into gear. I put the gear selector in D and I have to get the revs pretty high before the car starts to creep forward. When the revs build up more and the car shifts it will drive as normal. When it is struggling to move I noticed that if I hit the traction control button to be in winter mode it will drive off somewhat normal, it still feels as if the car is being held back a little. I also noticed that when this is going on and I put the car into neutral it is actually in reverse. I recently had the dealer look at the car to diagnose what the problem is. The first time I brought it in they said there was a leaky seal and had replaced it then topped of the transmission fluid. They also said that the whole shifter mechanism needs to be replaced as this is what's causing the transmission problems. A few weeks later I brought the car in for an oil service and while that was being done I had them look at the transmission again to see if they would come up with the same diagnosis, which they did. I then had said I would like to have the transmission fluid/filter changed. When I said that the person I was speaking with looked at me like I said something that was considered taboo. I had to keep from laughing because of the look on his face. My question is, does this sound like the transmission is on it's way out? Could changing the transmission fluid/filter aleviate the problem? I have owned the car since September of '08 so I am not sure how diligent the previous owner was with servicing the car. Although, when I got the car it was in very good condition on the inside, the outside had a dent on the front passenger's door. If I am in need of a new/used/refurbished transmission are there any good replacements? Or do I have to go to the dealer? Any guidance would be appreciated. Thanks, jfarias
You might have two problems here. The trans itself and the shifter linkage. For the transmission, if you change the fluid it could get much better or it could get much worse. If the trans really feels like it is on it's last legs, then by all means change the fluid and hope for the best. It could end up fixing all your problems in terms of drivability. But the downside is it could be the last nail in the coffin and the trans could fail completely with the new fluid. So that is the risk you take. There is a very good chance that the fluid has never been changed. If this car is in fantastic condition, in my mind it would be worth putting a new trans in it. You could even get a six speed manual from a 540i. That would make a great car. These are great cars, but expensive to maintain, so that must be taken into consideration. I would say have an independent BMW mechanic look at it and do the work. You can find one in your area by going to http://www.bimrs.org/ Or ask others here who they use in your area.
Thanks for the quick reply granthr, I've heard about the changing of the transmission fluid could make things worse. Any idea as to why? I do like the car alot (like you said, they are great cars), so depending on how much it costs for another transmission I will most likely replace it. I will try first getting the transmission fluid changed and see what happens (fingers crossed). I currenlty use it as my daily driver but with the warm weather coming I can use one of my other cars so I don't have to rush to get the 7 fixed so I can shop around for the best price. Again, thanks for the info.
That car was built during a time that they used "lifetime" fluids for the transmission and differential. Stupid idea, really, but since it wasn't designed to have its fluid changed, there is a possibility that it may get worse if you change the fluid. I think it depends on what is actually wrong with the transmission. Don't quote me on this though.
I don't know if this car had lifetime fluid or not. But what happens if the fluid is not changed dirt and crud builds up in the transmission. So when you put the new fluid in the transmission the fresh detergents in the oil get this old crud moving and it can block vital oil passages and cause the transmission to fail completely. It really is just a gamble. If the trans doesn't fail completely, it will probably run much better than before. Just be sure to put the correct fluid in the trans! You should replace it with what came in it new, IF it does have life time fluid in there. I am not sure, so if Paul doesn't know, email Mike Miller at Tech Talk and see what fluid he suggests. Good Luck
az3579 - I do know about the 'lifetime' fill fluid. But, there are some who still believe that it should be changed, to extend the life of the unit. One person in particular is from Roundel's Tech Talk. granthr - That is a good explanation, I understand now, didn't think of that before. I'll have to talk to my local mechanic and see if he has any experience with this situation. Thanks again granthr and thank you az3579 for the replies. jfarias
I have not had any problems changing the trans fluid on BMWs with this mileage or higher. I cannot guarantee you won't, but the ones I have serviced have worked better afterward. There is a chart on the internet somewhere that lists what type of fluids you can use. A shop with an Autologic, GT1, or at least the Snap-on MT2500 with BMW software can scan it to see if the electronic selector is giving the correct signal. I can't remember if this car has a mechanical portion of the selector or if it is all by wire, but either way, they should be able to sync them properly. Also, they should check motor and trans mounts because if they are bad and the motor/trans has shifted, then the selector (if partially mechanical) could be off. I will say that the shop just replaced a 740i trans with some of the same symptoms, but they could not get that one to move at all.
fluid change making things worse Another possible reason the fluid change can make things worse is a pretty simple one. the fluid is there to act as a buffer between the clutch discs in the transmission and to still provide some friction. Fluids that have broken down clutch material in them can provide more friction and sometimes mask an existing problem. But, just a little. So, some times putting in new fluid lessens the amount of friction to the point where the clutches slip the way they really should have been before. My brother used to tell me this when I was younger and I thought he was crazy. "Don't change the fluid unless it needs it. You're just asking for trouble" he would say. One day he was right.
dsheldon, In that case wouldn't you want to change the fluid sooner so you can catch those problems before they manifest? Anyway, I ended up bringing the car to 'Bruce Beard Automotive' in Middletown, RI and their diagnostic came up with the transmission needing a Valve Body Rebuild. After having that done everything has been good.
jfarias-transmission troubles J. I know it's already Jul 19, 2010. The last thread suggested a valve body rebuild. My wife had this done on her 171k 540i last year. This fixed the problem of the tranny trying to go into both first and reverse at a stop. Runs like a champ now. My 740i @ 161k now shifts hard in and out of 5th and I am contemplating the same rebuild. My tranny seems to be the sealed variety: no dipstick, no filler tube. Rick
