C4 leak

3T · Nov 30, 2011

It looks like it is leaking out the shifter shaft seal and the only fluid I see is closest to the tranny. Can anyone help determine if this is the inner seal leak or the outer by just looking? Trying to determine if I need to drain and take out the valve body or not. Also, anybody know how long these seals should last. I replaced both the inner and outer seal about 1-2 years ago.

BlackCat4 · Nov 30, 2011

Mine is leaking in The same spot it looks like The inner one to m.e my ?? Is How do i fix.

Viperwolf1 · Nov 30, 2011

There is a seal (Napa ATP 1404) around the shift shaft but you need to open it up and remove the valve body to change it. There is also a special quad ring (Napa ATP 12069) between the shift shaft and the kickdown shaft that can be changed from the outside.

Most likely it's the quad ring that's leaking. They just don't fit very well inside the shift shaft. Something that I have been doing lately on my rebuilds that has been working well is adding another small o-ring that goes in under the quad ring. This puts a little pressure on the quad ring to help it seal. Size is 3/8" ID (1/2" OD) x 1/16" wall. Just make sure it doesn't cause the kickdown lever to bind.

3T · Nov 30, 2011

OK I'll try that. Thanks!

3T · Nov 30, 2011

Viperwolf, if the o-ring is 3/8 ID and 1/2 OD wouldn't the thickness be 1/8" rather than 1/16"? And does it go in behind the H seal or in front?

Viperwolf1 · Nov 30, 2011

3T said:
Viperwolf, if the o-ring is 3/8 ID and 1/2 OD wouldn't the thickness be 1/8" rather than 1/16"? And does it go in behind the H seal or in front?

That size is what the package says. It's Brasscraft #0562 available at Lowes. I put that o-ring in the shift shaft first then the quad ring on top. It fills the cavity in the end of the shaft which is about 0.150". The quad ring alone is only 0.095" thick.

Here, I just happen to have some parts out.

3T · Nov 30, 2011

Oh I see! That is very helpful - thank you very much!

turbotim2 · Nov 30, 2011

3T said:
Viperwolf, if the o-ring is 3/8 ID and 1/2 OD wouldn't the thickness be 1/8" rather than 1/16"? And does it go in behind the H seal or in front?

When getting the thickness from subtracting ID from OD, you have to divide by 2 because there are essentially 2 thicknesses, thus getting 1/16".

Crawdad · Nov 30, 2011

I thought these trannys were supposed to leak?!! Heck I got antifreeze, tranny fluid and maybe some engine oil. I will worry about that next year.

Viperwolf1 · Nov 30, 2011

My C4 doesn't leak.

haydenjsle · Dec 1, 2011

I had my local tranny builder replace both seals on 2 separate occassions--still didn't cure my leak. I finally had to pull a donor C4 from the "U-Pull" Yard and have him swap cases--fixed finally.

IIRC, he said something about the case having too much wear around the shift shaft support. Hopefully, one or the other of the two seals does the trick for you.

3T · Dec 3, 2011

I'm guessing you have to drain the oil before changing this seal?

Viperwolf1 · Dec 3, 2011

3T said:
I'm guessing you have to drain the oil before changing this seal?

If you change the shift shaft seal, yes. If you just change the quad ring, no. That's why I recommend changing the quad ring first.

3T · Dec 3, 2011

That's what I wanted to hear!! Thanks

Blue Bastard · Jun 8, 2012

viper wolf are you sure of those part numbers on the quad seal.... i just ordered one from napa ATP 12069 and it don't look the one in the picture its just a oring. the other part number looks like the one in the picture.

Viperwolf1 · Jun 8, 2012

Blue Bastard said:
viper wolf are you sure of those part numbers on the quad seal.... i just ordered one from napa and it dont look the one in the picture ATP 12069 its just a oring. the other part number looks like the one in the picture.

No. That is the part number Napa shows for it.

Here are 2 other part numbers I found for it, 3499AL and 386078-S. Don't know the manufacturer. You might be able to get 386078-S at the Ford parts counter.

I get the ring in gasket/seal kits.

Blue Bastard · Jun 8, 2012

thanks for the reply. You are more than helpfull!

C4 leak

3T

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BlackCat4

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Viperwolf1

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3T

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