DIY: GM Trans Shifter Seal Leak Fix

[kouks]

I'm posting this since my search on google did not produce any usable results, so here is the short version of what I did. This is written for the M50 with the GM 4L30E trans, but other trans are similar. Most of this has to be done since our shifter is inside the trans tunnel and there is not enough room to access the seal in situ. If you just have a slow leak from the shifter seal, just deal with it, this is for major leaks.

In my case the leak was modest, but I had the car up on jacks already and the exhaust was already removed.

1. Remove exhaust
2. Remove center heat shield
3. Disconnect drive shaft from trans and disconnect center driveshaft bearing. Support driveshaft so it does not destroy the rubber seal on the center bearing and rear bearing. This is a good time to inspect the rear seal and guibo for replacement.

Now onto the real job

4. Remove the center U shaped trans support completely, including the support buckets. Most cars do not have a center support, but the M5x engine in the BMW e34 and e36 do. My 740iL does not.



5. Remove bolts from the sway bar supports, then back out the swaybar crossmember main bolt about 1 1/2 inches. Do not drop the crossmember, its not needed and it will act as a safety.



6. Use an engine lift or lift cross bar, loosen the engine mount bolts to near the top of the mounts, do not remove. Disconnect the intake boot at the MAF, disconnect the fan shroud and rest loosely on the fan, lift engine to the limit of the engine mount bolts.



7. Support trans with dependable jack and wood, or a trans lift, and remove the rear trans support, disconnect shifter cable. Lower trans about 3 inches, or until the shifter is easily accessible from level. In this photo I also removed the rear trans cover to replace the rear shaft seal (on lower left of photo) and the final drive seal (internal to the propeller shaft). Not required but you may consider it. If you do remove the rear cover to do that job, download the 4L30E rebuild manual since the parking prawl is in there and you need to make sure that is correct before reassembly. You will also need a seal for the cover itself, about $20 at your BMW dealer.



8. Insert the shifter seal removal tool, you can get it on Amazon for about $30. The tool comes with a 3/8 bolt that is too short (1.5 inches long) for the 4L30E, so I got a 3" bolt at Home Depot instead. The tool is called an SST-1001 GM Shift Lever Seal Remover/Installer (search for it on Amazon, there are several versions of this tool, and Snap On makes one with part number YA9348). It has an inner diameter of 12.5 mm or 1/2 inch, so it will work on any shaft diameter up to that. The outer diameter varies with the threads, but max OD is 18 mm or .7 inches.



9. Remove seal using the tool.



10. Insert new seal. The tool comes with a seal hammer, but it was too narrow for the 4L30E shifter. I think I used a 13mm long neck socket to hammer in the new seal. I used black gasket maker on the rim of the seal to ensure a good seal.



11. Reverse the process and done.

I have read that some could get the seal out with a metal pick or small screwdriver, but after trying that for two days and even using a small sharp knife with absolutely no success, I gave up and did the big job instead. Even if you CAN get it out with other tools, the problem then becomes, how do you hammer in the new seal without the clearance to use a hammer?

Like I said, if your shifter seal is not a major leak, deal with it, unless you really want to go through this pita of a job, or maybe you need to replace the guibo and you can do this while you're at it.

Good Luck.

[ross1]

Thanks for the follow up and concise procedure and good photos.
I can't help wondering if that tool was shortened it couldn't be used to grab the seal and then be gripped with a locking pliers or similar to yank that seal out.

[kouks]

Thanks for the follow up and concise procedure and good photos.
I can't help wondering if that tool was shortened it couldn't be used to grab the seal and then be gripped with a locking pliers or similar to yank that seal out.

You only have about 1.5 inches of clearance between the end of the shaft and the trans tunnel. I guess you could try it, but I don't know if you have enough leverage to pull the seal out. I read another thread where they used the tool and it took them several attempts because the tool stripped the seal rubber off and the have to go at it to catch the metal part of the seal. That's what I would be afraid of with a shortened tool.

Then you have the problem of hammering in the new seal, you have no clearance for that part of the job.