[yellow1098]

Hi guys! So I got my newly built 4L80e and 461 broken in and running and everything has been great except I have a large leak coming from the trans above the pan. We pulled the trans back out and had it check by a good trans specialty shop and he said everything was good with the seals and the pumps. In his opinion the bolts around the adapter plater are coming loose because they support the entire weight of the trans instead of the stock intended bellhousing. Not sure if that makes sense to me but I thought I would see if anyone else had any experience with this or could point me in the right direction.

https://youtu.be/xhYU5XrtL-4

[krisr]

My trans guy uses that CK adapter plate with the machined front pump half. I'll check with him next week if he's had anything like this happen with his 4L80's he's built, he's done LOTS of them.

[yellow1098]

Thank you Krisr! I would really appreciate it

[ponjohn]

Can you thread seal and / or blue loctite?

[Half-Inch Stud]

Adapter Plate or Bolt-On BellHousing. My adaptor plate is a flat steel, incapable of providing a leak. i dunno.

Photo and video indicate a Bolt-on Bell housing, and yea that can leak a coupla ways: uninstall, inspect , reinstall. Probably a high zone from the cutting, or a bad pump-case gasket, large O-ring not working?

Video sure helps minimize the tough to find leak.

[yellow1098]

If you click that YouTube link in the post you can see the leak

[grivera]

Is that a JW bell housing you’re referring to as an adapter?

[yellow1098]

I’m referring to the adapter package from CK performance to use the SFI bellhousing to a Pontiac block. Here is how it looks and attaches

[krisr]

I spoke to my builder today and told him about your issue and he said that it could either be 1 or 2 things. When the bell housing was cut off there is a high spot that the adapter plate is coming into contact with OR the pump gasket isn't right. What you could do is pull the box and paint the backside of the adapter ring with some bearing blue or something and bolt it down then pull it off and look for any witness marks where it may be coming into contact with the case.

[yellow1098]

Thank you so much Kris! You got me curious about about that bell housing point. Can you explain a little further what you mean by high spot coming into contact with? I really really appreciate your help and looking into it for me

[krisr]

The adapter plate sandwiches the pump into the case which is why the front half of the pump is machined flat so the adapter is square to the centreline of the case. If where the case is cut is "high", the pump won't be fully seated into the case so the gasket won't be doing its job once the pump starts building pressure -- that was what my guy told me to check for. You can probably just check whether this is a problem by crawling under the car while it's in the air and with a flash light, see if the adapter ring and case is making contact anywhere.

[chuckies76ta]

The pump has a gasket and a O-ring on it. That should be fine. The back of that adapter plate should have rubber o-rings that seal the pump bolts. When installing the bolts and o-rings they sometimes get twisted up or fall out and not noticed. Remove your bellhousing, then adapter plate and check for o-rings. The pump normally has steel flat washers that seal the pump bolts on stock tranny pump and housing.
When going to after market parts, these bolts that hold the pump in tranny housing still need to be sealed.
It's possible that the pump large o-ring did not seal properly. Easy change while you have the bell housing off and adapter plate. Pump is easy to remove with slide hammer. You could also change the front pump seal while at it. Make sure from pump seal gets lubed before installing converter.

Also, what has been mentioned above. With the stock bell housing removed, it is imperative that there is nothing hitting the adapter plate. you can go along with a feeler gauge and check for clearance.

I wrote all that and didn't realize the pump is part of the adapter plate. Still has to be sealed between adapter plate and pump. Let us know what you find.

[yellow1098]

I will be taking off the adapter plate and checking it out this weekend. But it would be great to find a great experienced tranny guy around here in Orlando Florida that could help if anyone knows of any. Kinda like yours you mentioned krisr but they are hard to find these days