Announcement

Collapse
No announcement yet.

C4 Oil Pan

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    C4 Oil Pan

    I'm having nothing but trouble with a leaking gearbox and I refuse to believe I'm unable to replace a gasket properly

    Some time ago I took the oil pan off the gearbox, hammered the edge as flat as I could get it and replaced the gasket with another cork one, replaced and all seemed okay for a long time but slowly it began to leak around the edges until it eventually gave way and flooded the garage floor.
    I got a new rubber seal, removed the pan, hammered it flat again as I realised I had over-tightened a little and this time spread a very thin layer of gasket sealer around the edge of the pan (this enough that it was almost see through), then did the same on top of the gasket and then fitted it back on the gearbox, tightening to the original torque spec that I found online somewhere and that seemed even tighter than when I put it on in the first place, in fact the gasket sealer squeezed out so it was clearly too tight and now it is leaking a fair bit.

    What is the best thing to do? Should I get a new pan so that it is machine flat? Are rubber gaskets okay? Don't use the sealer? Ignore the torque spec and just go for the trusty "tighten it until it stops, then half a turn more"?

    #2
    Seems odd that it's OK for a while then 'gives way'. Could the breather be blocked??

    Never use gaskets on any sump these days, always just some goo that comes with them. Some sort of silicone. It's so good that the biggest problem is them rotting through from rust because nothing seeps out to protect them!

    Comment


      #3
      If your garage was suddenly flooded then its a oil dump rather than a sump leak. If you leave a C4 transmission for more than about 4 weeks without cycling the running gearbox between drive and reverse then it will drop all the oil out of the converter into the sump which usually means litres of oil being dumped on the ground in a spectacular manner.

      If you exaggerated a little and its a bit of a weep from the sump gasket then the best approach would be to use some sealant on the gasket to ensure a good seal. I replaced the oil filter on my range rover box and the sump gasket didn't seal meaning I then had to put in a fresh 100 charge of oil and a new gasket. This time thin filmed with sealant. Second time, there were no leaks.

      Comment


        #4
        I had the same problem with my c4 I changed the sump and gasket with a brand new one still had a leak,which I thought was still coming from the sump but it turned out to be the gear selector shaft seal put new seal on now just a very small weep
        07 Cali special
        68 fastback
        75 grannycoupev8

        Comment


          #5
          What about the filler pipe and its O ring. I've had that leak and oil seems to go around the pan making it look like that is leaking.
          Allan

          Comment


            #6
            Like others I have a seeming leak, I fitted a drain into my sump and there is always a drip of fluid on it and the sump is wet (but little on the floor). Have tried different gaskets and sealant and I suspect its actually leaking somewhere else and finding its way down.

            '99 Bright Atlantic Blue Convertible (Stock) & '67 Acapulco Blue Fastback (393 Stroker)
            http://www.67mustang.co.uk

            Comment


              #7
              Filler pipe being loose can cause quite the leak

              Had a camaro a while back which had a clogged breather on the trans and it shot fluid out of the dip stick tube in a spectacular fashion

              Had a camaro that loved dumping the oil (as mentioned above) out of its torque converter in an equally spectacular fashion.

              Aren't these old cars great? Haha

              Good luck sorting your issue
              Please visit our Classic Mustang for sale site: www.classicamericancarsales.co.uk
              We stock a large selection of freshly imported Classic 1960s Mustangs. Fastbacks, Convertibles and Coupes. Cars are in stock in the Southeast of England with more shipping from the USA at all times. Other interesting American cars also stocked. CSRP disk brake setups sold

              Comment


                #8
                Thanks for the replies guys.

                I wiped down the gearbox then poured some more oil in and watched it as leaks began to appear around the pan, from the filler pipe and the selector shaft so I decided to order a new pan, to make sure it is perfectly machined flat and some new seals for the selector shaft. I spent Sunday under there replacing the selector shaft seals, removed the filler tube, cleaned it, put a new O ring on and for good measure ran a bead of liquid gasket around it before replacing. Put a thing layer of liquid gasket around the rim of the pan, sat the rubber gasket on top, then put a layer on top of that too and stuck that on. Tightened the pan nice and snug, not too tight. Gave it until this evening to set nicely before putting oil back in. Stuck the collection pan under it and checked a few hours later and guess what? Oil collecting in the pan.



                I'll have to wait until Wednesday before I have a chance to jack it back up and see where it's coming from now...what a nightmare.

                Comment


                  #9
                  Some of these old girls make us pay for the pleasure of owning them. My Shelby. Got a touch hot one day and steam pouring out of the engine upon entering a show. Lots of photographers appeared and I was the hit of the forums on FB for a while. I detected the thermostat housing had leaked at the gasket. Removed it, Cleaned it like an operating room. Installed.....water poured out!

                  Went on the net, read as much as I could on changing a gasket, Use string to hold the thermostat in place so it doesn't foul the mounting surface, Check the thermostat housing on a mirror to ensure flatness (it was) Use permatex, just a wipe not a ton on the surfaces. Use a good gasket...check, check, check. LEAKED!!! not a drip, a literally gush

                  Did I wait overnight? Gotta wait overnight to ensure it seals. Did it all over again, another gasket of course, Leaked like a sieve

                  Gave up and brought it to a shop. new thermostat housing and done.

                  Keep up the fight, you will get there.

                  Peter
                  Please visit our Classic Mustang for sale site: www.classicamericancarsales.co.uk
                  We stock a large selection of freshly imported Classic 1960s Mustangs. Fastbacks, Convertibles and Coupes. Cars are in stock in the Southeast of England with more shipping from the USA at all times. Other interesting American cars also stocked. CSRP disk brake setups sold

                  Comment


                    #10
                    Right, I've had a look under and although there is a little weep on the selector shaft, the pan itself looks nice and dry around the seal but the culprit is the filler tube! Perhaps the O ring I put on wasn't quite wide enough. I've read that the O ring should have a 3/4" diameter, does that sound correct?

                    Comment


                      #11
                      Originally posted by dbickell View Post
                      Right, I've had a look under and although there is a little weep on the selector shaft, the pan itself looks nice and dry around the seal but the culprit is the filler tube! Perhaps the O ring I put on wasn't quite wide enough. I've read that the O ring should have a 3/4" diameter, does that sound correct?
                      I have heard that finding the correct O ring can be a bit of a PITA. I'm thinking the original would have been an imperial size and maybe most modern ones are metric and maybe not an exact replacement. O rings are sized by either inside or outside diameter and the cross section (diameter of the rubber) If you have the original O ring and its not too damaged check that against your new O ring. Mind you the one originally in the car may not be correct.

                      If you get stuck this company may be able to help
                      https://www.allorings.com/British-o-ring-Size-Chart
                      Allan

                      Comment


                        #12
                        New filler pipe fitted, it was awkward to push in so you know it's a nice, tight fit. Put a bead of RTV around the top just to be sure and it's no longer leaking there.

                        I put 4 litres of oil in, which should be about half of what needs to go in (?) and it started to drizzle out of the breather hole at the top of the filler pipe, also, it's coming out of a little pipe above the selector shaft...

                        Click image for larger version

Name:	DSC_1457.JPG
Views:	77
Size:	51.8 KB
ID:	1254587

                        Is this some kind of overflow pipe? Is it now just leaking because there is too much oil? Should I drain some or has this done the job?

                        Comment


                          #13
                          Yes that is the overflow pipe. The gearbox is full of oil. It depends on whether the torque converter is full of oil also. I think it is better to fill these boxes whilst the engine is running and hence the gearbox oil pump is running. After all levels should be taken witht he car running and the box up to temp.
                          Allan

                          Comment

                          Working...
                          X