94 BMW 740 Transmission Problem Valve Body Check Balls

First, I want to thank the Automotive Forums for saving me a bunch of money. Because of the information I found on this site, my transmission problem only cost me $390 to fix, rather than the $5,000+ some mechanics wanted to charge me for a new one.

The information was found at www.automotiveforums.com/vbulletin/t38804.html (http://www.automotiveforums.com/vbulletin/t38804.html)

For an honest shop that is willing to work on the valve body (it's a very tedious process since there are a lot of small parts) contact Motor Speed West in Santa Clara, CA. E-mail: motorspeedwest.com.

The problems started when the transmission fluid was changed at around 130k miles. There was no problem moving in reverse, but once I shifted into drive the car wouldn't move. It seemed to clear once the car warmed up but then, as soon as I'd come to a stop, I'd have to hold the accelerator down to force the gears to engage with a big THUMP!; violently throwing the car forward. Afterwards, it shifted fine...until I had to stop again.

Thinking it was a fluid problem, I had the mechanic change it again. Ouch! You know how expensive BMW A/T fluid is. That didn't fix it. I had several mechanics say I needed a new tranny with a price range between $4.5K -$7K. The rebuilts were the cheapest but still over $4K. Thinking they were out to rip me off I turned to the internet and found information about the valve body and the check balls on this site.

Armed with a lot of research knowledge I called again to several shops and mentioned the valve body/check ball issue and none of them knew of it (so they say) but they did offer to inspect other potential problems for several hundred dollars which would be applied to the repair of the transmission.

A friend recommended Motor Speed West in Santa Clara, CA. And literally, within the first minute of telling the owner about the problem, he said it was the check balls in the valve body. YEAH!! How did he know about it and no one else? Because another customer had the same problem and his shop was going to do a replacement on his tranny and they noticed it was in perfect condition and decided to inspect the valve body. They discovered the check balls lodged in the chamber and diagnosed it as the problem. It seems they wear down just enough over time that when you change the fluid (thereby increasing the viscosity level) they become stuck in the openings they are supposed to only cover. They only dislodge after enough pressure builds up and forces them out (which explains why my BMW would THUMP and shoot forward). Think of yourself trying to force open a stuck door in your house.

To drive the point home, the check balls are only .5 centimeters in diameter and made of plastic. Half a centimeter!!! The cost is maybe $1 for two. Can you imagine a mechanic knowing this information but still charging you for a completely new transmission of $5K and only working on the valve body? How would you know if he gave you a new one?

The work on my BMW valve body update was approximately $400 (he was able to save my fluid and reuse it since it was only 1K miles old). And the best part, he didn't even charge me for the check balls!:2cents:

Hope my story helps someone out there. Oh yeah, and I had this work done over a year ago (4/12/05) and my 1994 740i is running perfectly...still.:grinyes:

Always blame the mechanic. I hope that E32 has the original nickasil block, and that your trans takes a dump. Maybe you should shack up with your new mechanic.

It seems everyone wants to pick a fight now a days. I don't see where I'm blaming a good mechanic. I did my homework and saved myself a ton of cash. Every other mechanic wanted to charge me up front a bunch of money. Whenever I asked them about the valve body and check balls they acted like I didn't know what I was talking about but were quick to say I needed a new tranny or something else expensive. A couple of shops it was the other way around, they didn't know what I was talking about. They were nice guys but clueless. Bad mechanics ruin it for everyone and this is probably one area they really can rip someone off. If you are someone that works on BMW maybe you should look at this as an opportunity to educate yourself about the valve body and turn it into an honest money maker. You might get a lot of business and good word of mouth. Maybe someone would take time from their busy life and make it a point to praise you on Automotive Forums. And I would love to shack up with my new mechanic, cause I know he'll never screw me. Can people say that about you?

Excellent success story! I knew of a guy who ended up paying $3500 for repairs, by which time he though about scrapping the car (or selling it) when someone mentioned to him about the check balls...so he ended up spending $4000 on his tranny by the time he got the REAL problem fixed...been find ever since.

Some times you can't blame the mechanic because most of them just don't seem to know...it's not hard to use a wrench to take off a bold and call yourself a mechanic...

Thanks for the story!