540 Transmission Problem

[stealthrt]

I recently bought a 1994 540 with a trans issue that I need to figure out. Often the trans will not have any power in first/second gear, almost like the gear is only slightly engaged. If you hit the M/A button into M then back into A it will then kick into gear and drive like normal. Shifting between gears is a little rough, but nothing too crazy.

The car also has a misfire that I have yet to diagnose but am leaning towards coil pack, along with a slight vacuum leak.. if those would affect the trans at all, I am unsure.

Could this be a simple TCU issue or is this an issue with the trans itself? I am not entirely sure how the M/A button works, as in whether it simply electronically adjusts the shifting points or if it does something mechanically?

Thanks for the help!
~Richard

[Hranj]

Are you getting a trans program error message on your dash? Sounds like a symptom of that. Check your fluid level first thing.

[stealthrt]

Are you getting a trans program error message on your dash? Sounds like a symptom of that. Check your fluid level first thing.

I got the error one time when I started having this issue and tried to power through it instead of switching into M then A(which obviously failed)

May be a dumb question, but is there a trans dip stick? I figure that it should have one being an auto, but can't find it :(

[PorscheH6]

BMW did away with the trans dipstick, so the 540 does not have one. Nowadays, BMW isn't even supplying cars with an oil dipstick on certain cars.

How many miles on the transmission? Sounds like it could be a worn valve body.

[stealthrt]

BMW did away with the trans dipstick, so the 540 does not have one. Nowadays, BMW isn't even supplying cars with an oil dipstick on certain cars.

How many miles on the transmission? Sounds like it could be a worn valve body.

The car has 70k on it, so I assume the trans does as well.

Ill check the fluid tomorrow.

[upallnight]

Warm up the trans by driving about 5 miles, lift the car up on four jack stand, with the engine running remove the fill bolt ( not the DRAIN Bolt) from the trans pan and see if any trans fluid comes out. If trans fluid doesn't come out from the fill bolt, get a pump and start pumping the correct trans fluid for your trans into the trans pan until fluid starts to come out. remove the pump and reinstall the fill bolt. Shut the engine and llower the car. Go for a test drive afterward.

[stealthrt]

Well, there was plenty of fluid in the trans, but it was pretty nasty fluid. I went ahead and drained the fluid and put new fluid in. It felt like it drove better on my initial test drive, but then later it went back to normal. As ideas?

Is there any way to pull the trans apart and test it? I have rebuilt several manual transmissions, but never dove into an auto before.

[Binjammin]

Yeah, you can take one apart, but be warned it's a heavy mother. You've got a 5hp30, you can check eriksson industries' website for all the exploded views.

http://erikssonindustries.com/

[kalevera]

Well, there was plenty of fluid in the trans, but it was pretty nasty fluid. I went ahead and drained the fluid and put new fluid in. It felt like it drove better on my initial test drive, but then later it went back to normal. As ideas?

Is there any way to pull the trans apart and test it? I have rebuilt several manual transmissions, but never dove into an auto before.


Sounds like the thing is due for a valve body. Did you use the correct trans fluid?

[Hranj]

Isn't there a filter for the trans fluid too? Maybe change that. Not sure if it will help much but it sure doesn't if you are just dirtying up clean fluid with a dirty filter.

[bahnburna]

Isn't there a filter for the trans fluid too? Maybe change that. Not sure if it will help much but it sure doesn't if you are just dirtying up clean fluid with a dirty filter.

if we were to look up most info on the automatic transmissions, the consensus is that you do not want to change anything; fluid or filter.
while that sounds suspect, the fact of the matter is, changing any of that will also remove the deposits that are contained in the fluid, and deposits on the clutches that actually HELP the trans shift. new fliuds have detergents in them, and will remove some of/majority of the deposits, causing slippage. if it were me, and having the extra scratch, id put in a 6 speed, thereby passing all the auto BS. i havent done that yet, but if i keep the car, id like to in the coming year or so.