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  •  » Transmission Leak C-4

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    9/19/2024 10:39 AM  #1

    riwall
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    From: Sherman, Texas
    Registered: 4/02/2013
    Posts: 223

    Transmission Leak C-4

    This has been going on for a couple of years. Occasionally I get a large puddle of transmission fluid under the car. In the past I would try to identify the source, clean everything up (yes, I've tried the white powder spray) tighten everything, change the pan gasket, etc. It would be OK for a week, maybe two and then another puddle. It seems to be coming from up top on the driver side. I finally took it to a transmission shop highly recommended by several friends. The chap suggested that as I had not really done much with the tranny in 20 years they should pull it and do an overhaul. I agreed and they did. 
    Well, I got it back last week and all was fine - until this morning when there it was, a large puddle. From what I've read, there is an overflow tube up top on the driver side. I've never overfilled the thing but I wonder if the fluid could be coming from there for some reason. 
    I'll be taking the car back to the tranny guy but I thought that maybe someone on the forum has seen this before. 
    I'm just a bit frustrated. Thanks for any suggestions.   Rick  

     

    9/19/2024 11:12 AM  #2

    BobE
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    From: White Plains, NY
    Registered: 4/04/2013
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    Re: Transmission Leak C-4

    Rick - what year is the car?

    Last edited by BobE (9/19/2024 11:33 AM)

    65 Fastback, 351W, 5-speed, 4 wheel discs, 9" rear,  R&C Front End.
     

    9/19/2024 12:06 PM  #3

    riwall
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    From: Sherman, Texas
    Registered: 4/02/2013
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    Re: Transmission Leak C-4

    Sorry. It is a '67 Coupe.

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    9/19/2024 3:50 PM  #4

    GPatrick
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    Re: Transmission Leak C-4

    Depending on the various parts that were used you may be getting drain-back when it sits.  You can do some searches for other solutions/causes but it is pretty easy to install a one-way check valve in the transmission cooler line which will prevent the converter fluid from draining back and overfilling the case leading to a leak.  Some earlier C-4's didn't have an internal check-valve and in some of the later units the valve was lost during a filter change.  Here are two links that may help - 

    https://classicbroncos.com/forums/threads/c4-purged-atf-or-mystery-leak.313552/
    https://www.vintage-mustang.com/threads/c4-question.943561/

    Helped a friend recently with the mystery puddle issue and a check-valve in the cooler line took care of it.

     

    9/19/2024 6:28 PM  #5

    riwall
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    From: Sherman, Texas
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    Re: Transmission Leak C-4

    I think that is REALLY HELPFUL! Thanks a bunch! My '67 would not have the internal check valve so when I take the car back to the transmission shop I'll suggest the check valve in the cooler line. I'm surprised that they didn't pick that up earlier as they have been in this business for decades. 

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    9/19/2024 7:27 PM  #6

    GPatrick
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    Re: Transmission Leak C-4

    Not all C4's do this from what I have read.  With my friend we also had a pump/case mismatch due to parts used from different years.  If I recall there were some drain holes/paths that didn't quite match up.  The correct pump was installed but the puddle persisted.  The check-valve cured.  One article stated that it could be in the outlet to the pump so you may want to do some more searches to see which side provides the best results.

     

    9/19/2024 7:44 PM  #7

    riwall
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    From: Sherman, Texas
    Registered: 4/02/2013
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    Re: Transmission Leak C-4

    Thanks again. I've had my Mustang for about 25 years and it started doing this only 2 or 3 years ago. One of the sites you referenced indicated that the valves are available at "Fitzall". I'm not familiar with them. Can you suggest a source? Best regards,   Rick

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    9/19/2024 8:50 PM  #8

    50vert
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    From: QLD Australia
    Registered: 4/01/2013
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    Re: Transmission Leak C-4

    https://www.fitzall.com/supportDetail.php?CR-1012-181

    "Those telephone poles were like a picket fence"
     

    9/20/2024 1:25 PM  #9

    riwall
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    From: Sherman, Texas
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    Re: Transmission Leak C-4

    Thanks. That should do nicely.

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    9/20/2024 7:52 PM  #10

    Greg B
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    Re: Transmission Leak C-4

    The c6 in my Galaxie is belching tranny fluid all over the floor when it sits.  I wonder if it's drainback as well and one of these would help it.   Thanks for the info!

    If multiple things can go wrong, the one that will go wrong will be the one that causes the most damage.
     

    9/20/2024 8:14 PM  #11

    riwall
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    From: Sherman, Texas
    Registered: 4/02/2013
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    Re: Transmission Leak C-4

    OK, I'll keep you informed. 

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    10/16/2024 8:58 AM  #12

    riwall
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    From: Sherman, Texas
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    Re: Transmission Leak C-4

    OK, I installed a check valve in the cooler line. Now we wait. Will advise.   Rick

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    12/28/2024 3:46 PM  #13

    riwall
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    From: Sherman, Texas
    Registered: 4/02/2013
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    Re: Transmission Leak C-4

    OK, I think I waited long enough that I can now state that the one-way check valve installed in the trans cooler line solved the problem. Thanks CPatrick. I was away for a week and feared having a surprise puddle of fluid under the car when I got home. Not a drop! What a relief after years of frustration!. 

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    12/28/2024 6:32 PM  #14

    GPatrick
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    Re: Transmission Leak C-4

    Glad it worked for you.  Did you put it in the outlet or return line of the cooler?  I think that over the years, parts from different transmissions may have been used and check valve function was lost.  Easy fix and for many older transmissions I would probably use one any time I did a swap or rebuild.  

     

    12/28/2024 8:10 PM  #15

    riwall
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    From: Sherman, Texas
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    Re: Transmission Leak C-4

    We put it on the return line not far from the radiator - because it was easy. I owe you one!

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