Automatic gearbox problem

[robant251]

At the end of last summer I purchased a 1998 E36 328i automatic convertible in extremely good condition with 69K miles supported by FSH. Lately I find that if I accelerate from rest with the gearbox in ''sport'' mode the first upward gearchange is very fierce. Subsequent changes are OK and the problem does not occur in ''economy'' mode. My after-market service manual mentions the possibility of low oil level but that this can only be checked and topped up, if necessary, by a main dealer. Is low oil level likely to be the cause of the fault and is it true that I cannot replenish the oil myself ? ( We have recently had a spell of sub-zero weather but surely that cannot have any bearing can it ?)

[Manolito]

A '98 conv with only 69k miles. Sweet.

In general, the colder the oil in this transmission, the longer it free-wheels between gears and the harsher the shift. That is a common complaint from new owners and they eventually get used to it.

BMW sold this as a 'permanent oil' transmission, but in fact, it should be changed every 50k miles or so. I change my e36 automatic fluid every 50k and I even change the liquid gold in my e46 automatic every 100k. I always notice smoother shifting after the oil change in my e36.

To check the oil level, you have to have the car level and the transmission at the correct temperature, which is monitored by the transmission computer. You don't need a dealer, but you need an indy shop with the proper computer connection to read the transmission temperature. That is why changing the auto transmission oil is one of the few routine maintenance jobs that I don't do myself. The "101 Projects for your e36" book describes how to do it, but I my attempt ended in a mess.

[bostogrun]

Usually a low fliud level problem will manifest itself as delay in torque converter kicking in from a dead stop. It's like it takes a little time to build up enough hydraulic pressure in the torque converter.

If you car is low on fluid, where is leaking from? Jack up the car and look around the tranny. Follow the cooler lines to the radiator ( a common place to leak). Look at the back of the output shaft any red liquid? Unlike oil tranny fluid cant be burnt like motor oil in the engine. It must leak and there are only a few places where these leaks can occurr. The cooler lines, especially where they have a flexible link, right under the power steering pump., where the lines bolt to the tranny, the seals where selector goes through the case, front and rear seals or the pan gasket itself: that's about it.

A rough shift is often the result of an accumulator issue. An accumulator eases the application of a band or clutch so you don't get a "bang into gear sensation"
This is essentailly a mechanical problem that can't be cured with fluid changes or additivies. Sometimes, Seafoam Trans Tune, can help 10% chance if a passage way in the valve body is gummed up. Ironically, this rough shift conditon can persist indefinately and have no impact on the longevity of the transmission.

I have a Volvo 850 that had a similar issue for 20k. Other than the bumpy shift from 1-2 there is no issue with slippage or rough shifts elesewhere. The reason that it's worse in Sport Mode is because the shift points are differnt in sport mode i.e. it winds out longer.

One other thought, is although I usually don't recommend it but, sometimes a power flush instead of the customary drain and fill of the tranny might help to dislodge any obstructions in an oil passageway. The safeway way to do this would be to buy a pan gasket and filter, drop the pan than put in approx 3.5 quarts of dexron 3 then go to an oil change place and get a power flush after you cleaned all the debris out of pan. It might work, your due for a fluid change anyway. This will cost you about $150. It's the only option you have short of pulling the tranny.

There are shift solenoids that can accessed through the pan i.e serviced w/o removing the tranny however there is usually a code associated with there failure. When a solenoid (an electrical device) fails the car most likely wont shift at all.