4+3 gasket question
Thread Starter
Pro
Joined: May 2025
Posts: 589
Likes: 137
From: OK
4+3 gasket question
I have what I gather is a common leak between the MT section and the overdrive unit on my 86, gear oil leaks down the pan on the OD.
Is the gasket for that in this felpro kit?
https://www.drivparts.com/part-detai...20Gasket%20Set
There is a gasket/seal kit for the OD unit but near as I can tell just looking at it they don't look like the one
I think I need. Such as this:
https://www.transmissionpartsdistrib...4-88-corvette/
OD works, trans shifts ok, I plan to rebuild them at some point if I don't go a different direction altogether but I need to replace the clutch
and plan to replace that leaking gasket and a few others that are handy while it's out without getting too deep into things.
I have the felpro MT kit, am I going to need anything out of the OD kit just to replace that gasket between the two?
I already put a new output shaft seal on the OD unit a bit ago.
I've also read that the case can crank causing a leak, I don't know if it's the OD or MT case, if anyone happened
to have a photo of where/how they crack that would be good to know.
Is the gasket for that in this felpro kit?
https://www.drivparts.com/part-detai...20Gasket%20Set
There is a gasket/seal kit for the OD unit but near as I can tell just looking at it they don't look like the one
I think I need. Such as this:
https://www.transmissionpartsdistrib...4-88-corvette/
OD works, trans shifts ok, I plan to rebuild them at some point if I don't go a different direction altogether but I need to replace the clutch
and plan to replace that leaking gasket and a few others that are handy while it's out without getting too deep into things.
I have the felpro MT kit, am I going to need anything out of the OD kit just to replace that gasket between the two?
I already put a new output shaft seal on the OD unit a bit ago.
I've also read that the case can crank causing a leak, I don't know if it's the OD or MT case, if anyone happened
to have a photo of where/how they crack that would be good to know.
Thread Starter
Pro
Joined: May 2025
Posts: 589
Likes: 137
From: OK
Technically, both lol. I've changed both fluids twice and see no evidence of mixing.
The AT leak looks to be from the cooler line fitting screwed into the case on the front above the pan rail and
is very small, the gear oil is from the mating surface above that where the OD and trans look to bolt together.
It's manageable but an annoyance. There are some other age related weeps of both but nothing of consequence atm.
I know I should pull both units apart while they are out and that
is usually how I do things but they both function fairly well and depending on if the clutch/flywheel fixes the problem I'm
having I may end up ditching this drivetrain so not putting more money/effort than is currently warranted
is a thing.
The AT leak looks to be from the cooler line fitting screwed into the case on the front above the pan rail and
is very small, the gear oil is from the mating surface above that where the OD and trans look to bolt together.
It's manageable but an annoyance. There are some other age related weeps of both but nothing of consequence atm.
I know I should pull both units apart while they are out and that
is usually how I do things but they both function fairly well and depending on if the clutch/flywheel fixes the problem I'm
having I may end up ditching this drivetrain so not putting more money/effort than is currently warranted
is a thing.
Instructor
Joined: Jul 2015
Posts: 102
Likes: 20
From: Syracuse NY
Technically, both lol. I've changed both fluids twice and see no evidence of mixing.
The AT leak looks to be from the cooler line fitting screwed into the case on the front above the pan rail and
is very small, the gear oil is from the mating surface above that where the OD and trans look to bolt together.
It's manageable but an annoyance. There are some other age related weeps of both but nothing of consequence atm.
I know I should pull both units apart while they are out and that
is usually how I do things but they both function fairly well and depending on if the clutch/flywheel fixes the problem I'm
having I may end up ditching this drivetrain so not putting more money/effort than is currently warranted
is a thing.
The AT leak looks to be from the cooler line fitting screwed into the case on the front above the pan rail and
is very small, the gear oil is from the mating surface above that where the OD and trans look to bolt together.
It's manageable but an annoyance. There are some other age related weeps of both but nothing of consequence atm.
I know I should pull both units apart while they are out and that
is usually how I do things but they both function fairly well and depending on if the clutch/flywheel fixes the problem I'm
having I may end up ditching this drivetrain so not putting more money/effort than is currently warranted
is a thing.
Thread Starter
Pro
Joined: May 2025
Posts: 589
Likes: 137
From: OK
I assume they use thin gaskets because there needs to be as near zero movement between case parts as possible.
