My car has a motor oil leak from the bell housing area, presumably, it's the oil gallery plug, but it also leaks ATF from the bell housing. I have done the Mercon SP drain and fill and did the waiting game to see if it clears up but it doesn't, and the level drops enough to start causing shifting issues. Filling it up with 1 L of Mercon SP via the trans cooler lines solves the issues, which confirms that my ATF leak is problematic and not a result of an overfill. However, this is not a sustainable practice. I last topped it off a couple of days ago and it seems to be at the correct level.

I found an independent shop that specializes in european cars. They often deal with Jaguars, Maseratis, and BMWs that have the ZF 6HP26. They are also willing to use any parts I supply if I choose to do so. For obvious reasons, I would like to stick with the Mercon SP. They looked up the labor time for dropping the trans and replacing the RMS and it came up at 6.2 hours, for which he quoted me $650. That doesn't include the cost of parts, but we all know the seals cost pennies on the dollar. They charge a $130 diagnostic fee that would be waived if I choose to proceed with the fix.

I forgot to ask them so I ask here, do they have to drain the ATF to drop the transmission and change the RMS and tighten the Oil Gallery Pump? What about if they have to replace either the transmission front pump seal or Torque converter seals?

Basically I want to know if I don't buy any Mercon SP, buy only a quart or 2, or buy 8 quarts to supply them with?

 

Hi Daniel,

Off the top of my head, the only concern with not draining the fluid would be fluid loss from the cooler line ports if the transmission is positioned vertically while replacing the seal or installing the torque converter. You could buy a pair of the cooler line flush fittings from a vendor like Summit Racing and put a little silicone sealant in the end of each one to create plugs to seal the transmission during the work. You would just clamp these fittings to the transmission with the existing cooler line clamping plate:




You could also probably seal the ports with standard rubber stoppers if you can find a suitable size.

Cheers,

Don

 

Pretty sure most of your fluid is going to stay in the trans pan and converter, it should need a little top up at most when done.

 

I am confused about the reference to RMS (Rear Main Seal) and then your comment about but it also leaks ATF from the bell housing.

The gearbox 'bellhousing' has nothing to do with a gearbox REAR MAIN SEAL. A TAILSHAFT SEAL on the gearbox would be a REAR MAIN SEAL on a gearbox.

I am guessing you are discussing the FRONT GEARBOX SEAL? (Torque Converter or INPUT SEAL?)

If I replace a front seal on a ZF AUTO gearbox without any other service, I place the gearbox in a vertical holder and lift the torque converter out, replace the seal and reinstall the converter!!!!!!!!!!!(gravity keeps the parts in line)
The fluid level SHOULD remain lower even if the gearbox seals are replaced with it in a horizontal position,(no leak) but the reinstallation of the torque converter is complicated by gravity pulling things out of alignment. I like dropping the converter STRAIGHT DOWN!!!!!!!!!!!!

Just a preference.

 

Good point, Bob. I guess I read Daniel's post assuming that while they had the transmission off to do the input seal they would also do the engine rear main seal. Is that what you're planning, Daniel?

 

No, it's the engine's Rear Main Seal and the Oil Gallery plug, and the Gearbox Front Input seal or whichever is leaking. Thanks for the information on placing the gearbox vertically, I will relay that to the mechanic.



Yes, exactly this. I need the gearbox input seal and the engine RMS done.