New rear main seal leaking

Hey everyone,

I’ve seen a few posts related to RMS leaks/replacement, but none about a new RMS leaking so figured I’d see if anyone has any ideas/tips.

A little backstory: My ‘09 4.0 V6 Prerunner started getting the dreaded torque converter shudder around 113k miles. Tried a fluid change + the usual Hail Marys, but eventually got sick of having to work around it (shifting into 4th when driving around town to prevent the clutch from locking up, etc) so I just decided to bite the bullet and have my mechanic replace the TC.

Good news is that the shudder is now gone (many dollars later). I’ve got a very honest and friendly mechanic, and he obviously suggested changing the RMS “while we’re in there” since it would add virtually no extra time and only about $30 parts and labor.

Like I said, shudder is gone, but I noticed some dripping from the bell housing after I got the truck back. Originally I thought it was tranny fluid (I first noticed it at night and thought it was pink, don’t roast me), so I brought the truck back immediately and he said it was engine oil from the RMS. I asked him if he got a bad RMS from Toyota, and he said that it was more likely an error on his shop’s end than a faulty part, so he would order another, drop the tranny again and personally install it (instead of one of his guys).

So he put in the new seal, and then calls me to inform me that it’s still leaking, but less. He chased the leak around and believed it to be the bolts, so he pulled them all out again, extra cleaned them and applied more silicone, and then was confident everything was sealed up.

I got the truck back again, and as you might have expected, more leaks from the bell housing (albeit way less leaking, but still dripping). I’ve already checked the normal culprits that get mistaken for RMS, but this is clearly coming from that little plastic window under the bell housing.

Thankfully this mechanic is hellbent on getting to the bottom of the leak, but I was wondering if any of you had any ideas of something he should be looking out for (e.g. easy to miss spots where you need silicone sealant. Certain types of liquid gasket not working well for this truck, etc. )

Disclaimer: If you can’t tell, I don’t do much home wrenching. I’d like to think I have a grasp on these mechanical concepts, but if any of my questions seem irrelevant or uninformed, they probably are.

Thanks!
-Christian

 

Wasnt leaking before torque convertor replacement at all?

 

My guess would be a gouged surface where the rear main seal rides on the crank, if he really did everything that he stated. This would likely have been caused by a botched removal of the original seal, and he may not have fully inspected the surface area assuming that it was not the issue.

Something like this

 

Yep,someone scratched the crank for sure. Idk if they're available for Toyotas,but in the small block ford world they sell a product called a "seal saver" Which is a very thin sleeve that gives the seal a new surface to ride on.

 

Did they reseal the rear seal plate?

Usually the plate is leaking as well and needs to come off, get cleaned and re-sealed.

I never change the seal without removing it.

 

sounds like your mechanic is trying to doing his best , mention to him the possibilities of what has been posted .

 

This happened to me once, I had pushed in the seal too far in and had to re do the whole job. The seal has to be sitting flush with the crank

 

Check this out :

https://www.tacomaworld.com/threads/brand-new-rear-main-seal-leaking.489716/

 

Pro tip, Don’t use Toyotas rear main tool SST it sucks balls. Use a wheel spacer to smash it on, the ID lines up with the seal perfect.

 

Really appreciate all of the input, everyone, and apologies for the delay in response - we've been getting flooded in SF the past few days.

I didn't have any leaking before the torque converter was changed, so it seems more than likely to be an install issue - at least my mechanic is convinced that the issue was on his end.

I really hope you're wrong about this, but unfortunately this seems like a real possibility. Thanks for that suggestion and photo for reference - I'll ask him to check that area when I drop the truck off tomorrow.

I'm guessing so, but definitely another possibility - I'll ask him about this tomorrow as well.

Of course there was a thread! Thanks for sharing that link.

I'm guessing this isn't the issue since the job has been done twice now, but definitely still worth mentioning. Thanks!

I'll be sure to report back with any findings. Cheers!
-Christian