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Intermittent no-engagement on 2004 BMW 3 series transmission

2004 BMW 330i 140k miles.

We first noticed this problem a year or so ago. At first, it happened only on cool mornings if the car had been parked outside. The cold car would require 3-4,000 RPM to move, forward or reverse. After about one minute or 3-4 blocks, the transmission worked perfectly at the touch of the throttle for the rest of the day.

It only happens about half the time. Other times, even if cool and after being parked for days, the transmission engages normally from idle and up.

Once recently, it deviated from this pattern. After sitting overnight, it started and pulled into the garage normally. I shut it off for a couple of minutes to place ramps in front of the tires and restarted the car. It did not want to move on the second start. It took 3500 RPM to climb the ramps. That was scary. The car has never suddenly engaged, but if it had suddenly engaged at that moment, it would have shot me through the front of the garage.

Last week I took it to the transmission specialty shop with the best reviews in town. As life would have it, he kept it three days, driving it four times, and it worked perfectly each time he drove it. Fluid looks fine (replaced at 120k miles) and fluid level is perfect. No codes stored in transmission computer.

I thought it was intermittently draining the torque converter until this last time when it failed after being shut off for only a couple of minutes.

The transmission guy is not interested in rebuilding the transmission even if I wanted to try it. He worries that because he does not know what is causing the problem, he might invest $4500 in that transmission and still have the same problem.

All theories welcome!

I had a very similar problem w/my truck’s (Ford) C4 transmission, and a rebuild totally fixed it. But it sounds like you did the right thing, find a good shop and your transmission specialist says it doesn’t need a rebuild. One thing that’s important, keep on good terms with that shop. They seem to be looking out for your interests rather than fattening their own wallets.

One idea, as a compromise, ask to have a proper transmission service done. That generally means to remove the pan and change the filter. It varies my make/model/year exactly what that means. If it does involve removing the pan, when they remove it the shop tech can sieve the fluid and inspect for unusual metal filings and metal parts that shouldn’t be there, like a broken off snap ring, and if all looks good they can simply replace the filter, then refresh w/new fluid. There’s some chance that could solve it, and even better, they’ll notice some problem they couldn’t notice without looking on the inside. And that job isn’t usually overly expensive. Well, it will be a BMW price version of what would probably cost out considerably less for a Toyota Corolla, but you already understand that.

Thanks for the comment. The shop charged me $0 for having the car in their shop for three days, so when I went to pick it up, I took a bag of cinnamon roles from Pannera Bread for the folks in the shop.

Sounds like something may be sticking in the valve body of the trans… Might be a good candidate for an additive that specifically mentions the valve body. I think Berrymans has a few

Try this as an experiment…instead of going from reverse to Drive… Put it into the lowest gear you can select…see if this delay is present when you do this. If not…it is something not moving when it should inside the valve body most likely…an additive can help this. A simple experiment.