Got a 1988 5.0 EFI in a 69.5 maverick, with a C4 tranny. When I first put the tranny in, it worked fine, shifted solidly when put into gear,, now, Im losing my forward gears,,, reverse works great,, never had trouble with that,,, I adjusted the bands, no help, made it worse actually,,,, Fluid is not burned, but have a suspicion on the vacuum modulator. Soon as I hook up the vacuum line,,,, no forward gears at all, has a whirring sound in the tranny, like its in nuetral. Unhook the vacuum line, and it will slowly come back, but it acts like it has a stall converter in it,,, got to rev it slightly to get it to move forward,, when it does,, its like WHAM!!! if you keep your foot on the gas and keep the rpms up, it stays enguaged, if it goes back to idle,, it like goes into nuetral till you rev it up again,,, then WHAM! I belive the hydralics of the tranny are working fine, but have never tested line pressure or anything like that,,,, Can the vacuum modualtor create such a problem to not wanna go into gear instead of slipping, or freewheeling? Ive got another tranny, from the 6 banger engine,,, I know it worked and may be a weaker unit than the V8 trannys,,,, but,, whats a guy to do when you got more time than money??? Not afraid to tear into it and make 2 into one, but, making sure my options are covered before I remove the tranny from the car. Any ideas??? ChadS
Check the following: 1) Fluid level... if it is low it will act like a stall converter... 2) IF you have a pressure gauge, install it into the port on the side of the transmission and get the readings on it. 3) Drop the pan, check for clutch material, and change the filter... Its alot of work... but if its a clogged filter its really cheap. And your going to need the new gasket and filter if you need to rebuild it either way.... As for the other transmission... if it worked beforehand and has been kept out of the elements, you could always swap it in if it will bolt up... and therefor i reflect back onto my previous statement of the filter/fluid change... as you will need to fill that transmission with fluid either way, and a new filter is always a good thing.
Was the tranny rebuilt or used when you first installed it? Pressure check is first thing to do as well as the filter change and pan particles inspection. Sound's like a sealing ring or other leak. Leaking valve body or sticky valves, maybe. I would pull it out and open it up to look at the internals for wear and broken pieces etc. Maybe a band strut has broken or the band itself??? Need to look at each and every part though, to determine the cause. Get a rebuild kit just in case and you can always go through the spare one for some hands on experience.
Yeah, did all of the suggested, no help. I started taking the 6 cyl trans apart yesterday. Found a small plastic ball with a stem, like a delta sink valve,,, has an oring around the ball..... found it in the pan,,,, any ideas? I gotta get a book on the C4. Chad
Exactly what he said... Toss it... That means your the first person to rebuild this transmission which is good because you dont have to deal w/ wondering if someone else took it apart and screwed with it. Honestly.. Id just rebuild this tranny, and swap it out w/ the one in your car now... and then rebuild it for practice, and that way you have a spare on the shelf also Have fun
