ZF Transmission Flush DIY: Word of caution on gasket
 

A few weeks ago I changed the trans fluid on my recently purchased '04 530i with 106k on the odometer. After doing so, and changing the pan/filter assembly, I noticed that there was a slow constant leak, even when the car was not running. Inspection revealed that oil was seeping from the pan gasket area, and re-tightening the bolts had no effect.
So, I had to drain and take the pan off to figure out what was wrong. I read other posts referring to a 'warped pan' but with so many bolts holding it on, couldn't believe that was the case here.
Washed out a catch container to re-use the fluid, and drained the fluid in and took off the pan. Nothing was obviously wrong with it, and the tranny gasket sealing area was clean. After pulling the factory-installed gasket off the pan and running my fingers along it I could feel areas of inconsistent thickness, where it had been deformed in the pan gasket channel. Inspection of the pan channel revealed pan molding deformations and some loose molding flash stuck in there that apparently had prevented the gasket from sealing. After cleaning this out, lining the gasket channel with permatex liquid gasket, and re-installing the gasket, all leaking has stopped.

So, before going to the trouble of doing your flush, check the pan gasket channel and make sure it's clear of debris or you might have to do it all again!

Funny you posted this....

I did a big Mechatronic overhaul just a couple of months ago. Yesterday I had the car up on a lift to hunt for a suspension noise, and I figured I'd peek at the oil pan and trans pan gaskets since I was there.

To my shock I found a slight fluid seep at the rear of my freshly installed pan with a brand new gasket and new bolts. I followed ZFs recommended procedures to a T, including torquing all pan bolts to the recommended spec and in the correct sequence. Now that you've posted this, I think I know why my pan is seeping.

When you put Permatex in the groove, did you do it BEFORE you set the gasket in the groove? Or did you put the gasket in the groove and then run a bead of permatex over the gasket? From what you posted it sounds like you did the former.

Thanks for giving me yet one more reason to think ZF absolutely blows a male camel's ass when it comes to manufacturing transmissions.

Hi be sure to check the transmission wiring connector seal, this may be what is causing your leak if it's at the back. With my leak, it appeared to be coming from all around the transmission pan because the channel would fill and leak from about everywhere at once.

The steps I followed were:
1 pull gasket, clean channel as much as possible, locate and remove debris
2 run a bead of liquid high temp silicone gasket into the channel all the way around, and push the rubber gasket into this until it seated, wiping up excess especially from the inside of the pan.
3. wait 15 minutes to allow the silicone gasket to set somewhat
4. install the pan, only torquing to medium screwdriver firmness
5. wait 45 minutes to allow the silicone to firm up
6. torque the pan the rest of the way, following approximately the torque pattern, fill fluid.

Edit: and to be fair, I can't guarantee that this was a ZF manufactured pan. It didn't appear to be labeled as OEM.

Nope, its the pan gasket.

Regardless of who made the pan, ZF sucks.

Thanks for the tip. I'm not going to do anything with it at the moment. It's a very slight seep, nothing too alarming. Maybe in a couple of months I'll pump some more fresh fluid in and reseal the pan.

I checked the gasket on the pan I received by running my finger along it.

I also ran clean ATF over the whole gasket with my finger before installing it.

I also did not tighten the bolts to spec as I was afraid that was too much force for a reused bolt.

Pan is still dry as can be and going to drain for a 3rd and final time next W/E for next 30,000 K interval.

running your finger over the gasket without removing the gasket will not find this issue. You have to remove the gasket and look at it and the channel. Most pans won't have this issue, like yours, but I posted so that, for the few that do, some users will catch it before installation.

I can understand but had there been an irregularity I might have felt it.

Maybe also is the fact it was a warm day when I did mine, and the gasket may have been a bit soft.

A bummer, however, to have a product with that problem and the resultant issues you experienced.

Take a look at this thread as it has good info:

https://5series.net/forums/diy-do-yo...-refill-88129/


And this one as well:

https://5series.net/forums/e60-discu...arison-115742/

Instead of removing the pan and the gasket to make adjustments or to start the process all over again, why wouldn't you do the following:

A) buy Permatex Right Stuff and run a bead on the outside of the gasket where its leaking or

B) buy Permatex spray and spray it on the outside of the gasket area where its leaking

That thread is over 4 years old