I've got a 74 C4 tranny in my pickup and the problem I am having is repeatable. When driven for the first 5 minutes, it does not want to shift out of low. After 5 minutes it shifts fine. I've checked the fluid several times when in park and after driven awhile, it shows full, doesn't smell, and is nice'n pink. I've removed the rubber hose leading up to the modulator, and stuck a pipe cleaner in the hose to see if the modulator was leaking fluid, but nothing. I've hooked up a vacuum gauge and at 800 rpm my vacuum reading was 13, and at 1500 rpm it was 18. The tranny dipstick is a Lokar dipstick, and the previous owner looks like he has cut the bottom of the dipstick off to aid in showing where the full mark is, so maybe its possible it is not really full, but it has been this same level for over a year now, and this problem only started a couple of weeks ago. I'm no expert by any stretch, and am not sure what to test next with basic understanding of c4's, so I am wondering if anyone knows a knowledgable person on older trannies like mine in the Burlington area.
drain the trans, fill it to the proper level to what it is meant to hold, then check the dipstick level, the motor in my truck on the dipstick says im 2 liters over full at the right amount of oil its suppose to have, cheap aftermarket chrome stick is wrong. low trans fluid might not cause your problem but its worth a try, trans works on pressure, low fluid for a long period of time may have wrecked ur pump, the problem may now be showing itself
well the modulator was ok, but not so much for the torque convertor, pump bushing, a valve and spring kit, and an overhaul kit. The tranny guy said it was an old rebuild, and I just happened to come around at the wrong time when I bought the truck. I seem to have bad luck with trannnies, my wife's 2005 escape was shot and out of warranty but they had recalls on them for 2004 and older, and it sounded like mine had the older style thrown in from what the mechanic said, and recently my lawn tractor doesnt even want to climb a small incline.
