1977 Mercury W/ C-4 Trans. 351W engine, No forward gears
So far tried tightening bands, they were very loose. Pulled pan cleaned valve body and filter drained fluid. Everything was filthy, I don't know how anything was getting through the filter, and the fluid smelled slightly burnt. Going to try the low-reverse servo next, then the modulator valve. Doesn't even kick in at the D,2, or 1 positions, it's just like putting it in neutral. Any help or advice would be appreciated. Thank You. Greg Johnson
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Hi , being that the transmission shouldn't have a dipstick, the transmission pan will need to be removed in order to remove and change the filter, pretty straight forward , after the transmission lower pan bolts are removed, clean the pan and remove the filter by carefully pulling it from the valve body , a slight twist and tug should do it . than replace the filter by pushing it back up into the valve body. replace the blots and torque to 14 inch lbs.at the top of the transmission their should be a red or black fill plug . add 4 quarts of fluid to the transmission through this hole . start the car and run it through the gears . now back under the car there is a small 11 mm plug at the drivers side of the trans near where the axel shaft comes out ... remove this plug/bolt with the engine running and car in park . fluid should trickle out of this hole , if not still with the engine running pour additional trans fluid in the fill hole until fluid starts to trickle from lower hole , once that happens replace the 11mm bolt in the lower hole and replace the fill cap. road test the car and your all done
could be the forward gear bands actuator , its part of the valve body in the lower part of trans , it has all sort of solinoids in there that make gears shift and select direction
of course if you dissasemble this that far it would only make sence to rebuild the entire thing
There's only two real solutions here. One is replacing the control module in transmission inside of pan bolted to valve body. Pretty straight forward and easy to replace once trans pan is off and filter removed. Second is the trans mission needs to be rebuilt. If the gear 3 is gone the expect trans rebuild
The band adjustment in not a torque adjustment. Drop the main pan on the transmission. You will see the valve body with filter on it. At the rear drivers side you will see a round dome piece with a flat flange with four bolts in it. Remove the bolts and take this cover off. Now you will see a round piston with an adjustment screw in it. Break the jam nut loose and tighten the allen bolt in until tight. Back off five complete turns and reset jam nut. When you have the pan off, take note of how much clutch material is in it. If you have a lot it could be time to replace the clutches. Also it is a good idea to put in a new filter if you are in there. Good luck
The correct fluid to put in a 1997 van is (ATF-3). Sounds like you need to make adjustment on both the forward and reverse bands of the transmission to correct your problem. The kickdown band (front) forward is located at the top (outside) of the transaxle near the front. To adjust the band,loosen the lock nut approximately 5 turns. With the lock nut loose the adjusting screw should turn freely in case. Tighten the adjustment screw with an inch lb. torque wrench to 72 in-lbs. Then back the screw out 2 1/4 turns, hold the screw in place and tighten the lock nut to 35 ft-lbs. Then after removeing the transmission pan and filter the low-reverse band is located next to the valve body. Loosen the lock nut 5 turns so the adjustment screw is free. Turn the adjustment screw in to 41 in-lbs, then back the screw out 3 1/2 turns. Hold the adjustment screw and tighten the lock nut 10 ft-lbs. Install transmission pan/with gasket and refill transaxle to proper level. Test drive van. Be safe and block the rear wheels before you raise the van and try to work under it. Hope this will help you.
Generally, what causes C-4's and C-6's to be slugish going into gear, is the seals on the servo pistons are getting hard. The servo pistons are what apply pressure on the clutch packs, when the seals get hard the oil can blow past the piston and the clutch won't engage. It's worse when the the trany is cold and usualy gets better as the oil gets warm. You could try some transmission conditioner, the cheep stuff works as good as the high dollar stuff. Don't rev the engine to try to get it to go into gear, the clutch is trying to engage and you will burn the clutch up pack. If the clutches were replaced 3k miles ago why didn't they put seals in it at the same time?
Its your body valve in the gear box which is not letting the pump on forward gears pump enough oil to the forward band and because the band isent tight it is slipping..
Now it could be the oil in box and if you take off the auto pan and clean out the filter on the pick up and refill with DEXTRON II TRANS FLUID then you should be ok as long as it hasent slipped to much .
Let me know how you get on . RON
Well, there aren't really THAT many clutches in an automatic trans. The older ones had 2 or 3 and 2 band brakes that controlled 2 or 3 forward speeds and reverse. Newer ones have one or two more for overdrive and more speeds. Your jeep is more like the older style, with a lockup torque converter added. The original problem sounded like a piece of contamination in the tailshaft governor, and the best thing was (once it started working again) to leave it alone. The old Chrysler owners manuals told you not to touch the transmission, EVER, unless it was being used for a taxi or towing. The risk of additional contamination far outweighed the benefits of changing the fluid. Your problem now sounds like the valve body is contaminated and something is stuck. There are lots of little spools and valves that are machined to very tight tolerances. Little fibers from clutch wear and filter changes can cause this. It's got pressure, and it's still got clutches (it wants to be in 1st gear). A new valve body is a good bet to fix the problem, but the best thing is to take it to a transmission guy you think you can trust to test the pressures in the valve body and determine what is actually stuck and tell you if it can be repaired or needs replacing.