Howdy y'all - Hoping to figure this out! I had a pretty steady leak out of the back of the transmission pan, so I decided to do a filter/gasket swap. That didn't work...kept leaking, so I ordered a new pan and gasket. The new pan is a Scott Drake, nothing fancy. Anyhow, I continue to have a worse leak than ever. I torqued the pan bolts to spec, using a cross pattern. I thought maybe I had overtightened, so I backed the bolts off a tiny bit. It seemed to work at first (no drips for like 20 mins), but now it's worse than ever. The tranny didn't leak until recently (maybe a drip or two every couple days). The new gasket is rubber, which is what was in there before. Any ideas? Thanks as always, RNY
Starting a new thread about this kinda muddies the water. How come you didn't just post it on your original thread?
https://www.jalopyjournal.com/forum/threads/c4-tranny-mystery.1263085/#post-14471058 I take it that is the original thread. Did you check that either pan sat flush against the transmission without a gasket? Gasket is only there to take up the minute surface imperfections, not to seal two surfaces that are damaged or badly machined. The pan should sit flush against the case with no rocking or misalignment. Even new tin will have pooches and wows that will be need to be taken out to sit flush. I probably spent the most amount of time on an engine just getting the tin to sit flat. Don't care for rubber gaskets on old tin work. Newer vehicles that use 0-ring type gaskets are fine for rubber, not so much with older iron. Prefer the cork rubber type from Mahle/Victor Reinz. It's a bit thicker and much more durable that regular cork. Especially if you need to adjust valves regularly. Rubber does not fit the minor imperfections as well and they always seem to fall apart or split near bolt holes, even when not over-torqued.
Helped a friend fix a pan leak on his daughter's OT daily driver, he had been talked into buying a replacement transmission pan to go along with the new filter, once he was done "fixing" things the leak was far worse. To start off he used foot-pounds instead of inch-pounds when tightening the pan bolts, how he didn't strip out all the bolt holes I don't know, also, the pan was made out of metal so soft I could twist it into a pretzel with my bare hands. I got the original pan out of the trash, took it home and spent some quality time flattening and straightening the mounting flanges, also dimpled the bolt holes "down" using a small diameter pipe and a ball-peen hammer, problem fixed.
I used those valve cover hold down spreaders on my trans pan on the truck when I had a bit of a drip. None now. Adds a bit of bling as well.
Not sure if they are made for transmission pan gaskets, but recently did an OT car and the oil pan gaskets (rubber) had steel inserts. Snugged it up til I was on the inserts and all was good. No chance over over tightening (within reason).
My 29 P.U. has a 73 C4, had a leak problem, Found and fixed it was the cooling lines, the Forward Line (closest to radiator) is the pressure line, rear line is return.
We always use Permatex Right Stuff sealer on just about everything these days, otherwise the odds of you having recurring leaks are very high. Be sure to follow the instructions and let it set up, don't rush the job.
Looks like the leak is fixed...two cheap rubber gaskets later, I bought a silicone/aluminum gasket and no more dripping. Shifts fine, but I have had it "slip" out of gear (or not engage) in 3rd gear when cruising at about 2800rpms. Fluid level looks good on the stick, just a 1/8" above the do-not-add line. Wonder if my tranny is on its way out. Thanks for all the help y'all.
Check the actual level of the Trans. if the tail shaft angles downward, You should bring the fluid level to the "TOP" of the Full line, The Dipstick reads from the front of the tranny, with the rear pointed downward the pickup/filter could be starving for fluid, as was the case with the C4 in my 29 Model A
Like AHotRod does! .....I continue to 'axe'....why would anybody use a gasket on an oil pan or tranny pan anyway?! Clean with laquer thinner (NOT paint thinner) really well...pan and tranny... squirt on the RTV/PermaTex/gasket maker call it what chew will and let it firm up before putting oil back in. Axe yourself...how often do you pull the pan?!....every 5-10 years?! Seal it up and move on. 6sally6
The saga continues... I don't think the engaging/popping out of gear issue is a fluid level issue. I very carefully got the fluid level right. A buddy asked if the new pan was as deep as the old. I think the old one was deeper, but I tossed it so don't know for sure. Anyhow he thinks the pan might be in the way of something. There is an intermittent whine that wasn't there before. Anyone ever heard of such a thing?
Restricted filter, pump or converter will whine. Did the new filter have a screen mesh or was it Dacron? I have had some Dacron filters that were too restrictive creating a whining noise
Only whine I had in a automatic, was a TH 400. Was making a whine, not shifting properly, took it in and the “freed up” a sticky valve in the valve body. Started aging again, and a new BM valve body cured it. Not saying run out and buy a new VB, but maybe a transmission shop could diagnose it properly.
Old filter just had screen mesh, new filter has a screen and a circular rubber grommet on the bottom side.
The filter with the grommet on the bottom is the filter used on the Bronco C4 with a deep sump pan. An extension tube pushed into the filter so it could pickup the oil at the bottom of the sump. Don’t know if it would create a problem if the flat C4 pan was used,maybe if you have the pan with the sump and no extension tube it could starve the pump.
Oh man that could be it. I think the C4 I have is out of a maverick. I didn't think they'd be different so I got a filter for a Bronco. I think I'll swap out for the other type of filter without the grommet. Hope that does the job. Thanks man!
That’s a 4x4 filter and the circular rubber grommet is stuck to the bottom of the pan. No oil flow to the pump!
Having done it myself a time or two, I feel for anyone who works on a vehicle only to create more problems.
Never ever use rtv on a trans pan!! ATF turns it into goo and it will mess up a trans in a hurry. I have built 100's of transmissions and the only sure fire thing I found to seal one with no leaks other than making sure the pan rail is perfectly flat, use a cork gasket and spray both sides with Permatex high tack.
Makes sense...can I just remove the rubber grommet? Or get the other screen type filter with no grommet?
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