Transmission warning symbol recently came up and my car went into limp mode (car would also struggle to shift into reverse). A friend of mine cleared the codes and it went back to normal but I got it checked out anyway just to be safe. The mechanic is convinced the transmission (ZF automatic) has to be fully replaced as the transmission fluid is completely black and has metal particles in it, and he says he feels the gears slipping during turns (which I don't really notice myself). I'm wondering if there's any way to be completely sure a full replacement is necessary or if replacing the fluid would be enough. The error codes were gear monitoring 3/4 and a turbine speed fault, which is the exact same as this article in which the issue was the TCM module. As a side note the issues started a couple of days after driving in heavy rain, so hopefully the problem is due to a sensor issue. Any advice would be appreciated!
If there are metal particles in the transmission fluid, that means there is now less metal in the transmission. A fluid change is never going to fix that.
I haven't seen it myself but as far as I understand it's not unusual for some fine particles to be in the fluid due to wear. The transmission also feels fine while I'm driving, it was only when in limp mode that I had issues shifting into reverse. It is very possible that I'll need an entire rebuild but I'm just trying to eliminate all possibilities before making that decision.
The trans is on the way out. Be thankful it gave you some warning. Mine went south on a drive to San Diego, no warning. Luckily I got it into limp mode and was able to drive in 3rd gear all the way back to LA.
Oddly, reverse is often the first gear to go in these. The DIY isn't that difficult. But if you can't, look for a low mileage trans and just swap it.
Current stable:
2002 525i (Daily Driver)
1994 SN95 Mustang 'Vert (The Bumblebee)
2001 325i Convertible (Beach cruiser project)
I'm still not sure the error was due to a mechanical problem with the transmission. Got the fluid changed today (and filter/ gasket replaced), this is what the magnets and old filter looked like:
https://ibb.co/JFMswP6
https://ibb.co/G0TY8dk
How doe`s it drive now ?
Mart.
Current stable:
2002 525i (Daily Driver)
1994 SN95 Mustang 'Vert (The Bumblebee)
2001 325i Convertible (Beach cruiser project)
If the ATF level were low, that may account for the lack of drive when cornering as reported by your mechanic. The TCM could also throw a speed sensor fault because what the input sensor is reading is not reflected by what the output speed sensor is reading. The same applies to the gear monitoring fault. The magnets don't look too bad. If the trans has been filled following the procedure closely, you are going to know in a day or too if the fault codes return or the trans goes into limp mode again.
Car is holding up so far and the transmission still feels fine, we’ll see what happens. Car has 120k miles and as far as I know the tranny fluid had never been changed before (gasket and filter were factory originals). Any idea as to when it’d be good to change the fluid again to eliminate more of the old stuff?
Last edited by simoo; 01-17-2023 at 03:10 AM.
Sidenote: I got the fluid changed at another mechanic because I wanted to get a second opinion. I went for a drive with him and he said the transmission felt completely fine, so I'm not sure if the first guy noticed something or was just pushing for a transmission change..
How is it driving now ?
Mart.
So far no issues, not sure how to determine what the problem really is/ was...
You probably had slippage of the friction discs, potentially because of low pressure to one of the cylinders. That oil was really black.
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