rootbailey Posted March 26, 2018 Report Share Posted March 26, 2018 Need help with my 79 620 automatic wont change gear 1 Quote Link to comment
datzenmike Posted March 26, 2018 Report Share Posted March 26, 2018 Need much more info. Does it stay in first then, and not up shift? or does it not even go into any gear including R?? While I'm here... Is the transmission fluid at the full mark but NOT overfilled? What color is it? Brown, Tan, Black, Brick red or clear see through Red ??? 3 Quote Link to comment
rootbailey Posted March 26, 2018 Author Report Share Posted March 26, 2018 It just won't shift it will go in gear Quote Link to comment
rootbailey Posted March 26, 2018 Author Report Share Posted March 26, 2018 Trans fluid is brick red and how is the proper way to check the fluid 1 Quote Link to comment
Dolomite Posted March 26, 2018 Report Share Posted March 26, 2018 Most auto trans are checked warm, idling on a flat surface. I’m sure Mike will let us know if this is the way to check a 620. 1 Quote Link to comment
Charlie69 Posted March 26, 2018 Report Share Posted March 26, 2018 Warmed up idling in park. Be sure to use E brake or block tires. Pull trans dipstick, wipe clean with clean lint free rag, insttall dip stick fully into dip stick tube, wai a couple seconds and pull dip stick to see fluid level. Be sure vehicle is on level ground. Do not over fill. https://www.wikihow.com/Change-Your-Transmission-Oil 2 Quote Link to comment
G-Duax Posted March 26, 2018 Report Share Posted March 26, 2018 Many auto trans problems are caused by plugged filter screens, and seeing your fluid is brick read, it probably on the beginning of the end. It should be a nice clear red. If you have been driving it quite a while with dark fluid, you may have hurt the trans. If I was you, I would take it some where, have the filter changed (in side the pan), and fluid flushed. Don't just let them drain it when they change the filter, make sure they flush the converter at the same time, as it holds quite a bit of fluid. 1 Quote Link to comment
rootbailey Posted March 26, 2018 Author Report Share Posted March 26, 2018 It has sit for 15 years just trying to get it going 1 Quote Link to comment
flatcat19 Posted March 26, 2018 Report Share Posted March 26, 2018 Ran when parked, but parked because of transmission problems. You, sir, just got what many of us never had. The reason. 3 Quote Link to comment
datzenmike Posted March 26, 2018 Report Share Posted March 26, 2018 So to recap... It will definitely go into Reverse and Drive, but won't up shift out of first? Look at the back of the intake for a small metal pipe from the intake going down and beside the transmission. It may be connected by a small rubber connecting hose to the large fitting that the vacuum line for the brake booster is connected to on the intake. Make sure it hasn't fallen off or was removed or and rubber hoses are cracked and not getting any vacuum. Now check the transmission end. There will be a small rubber elbow hose to the vacuum diaphragm. Low or no vacuum fools the transmission into thinking you have the throttle fully floored and delays the upshift. With the engine off but ignition in the ON position and nice and quiet. Step slowly down on the gas pedal. Just before it touches the floor you should hear a nice 'click' sound from the kick down solenoid switch. If you listen at the transmission on the driver's side you should hear the solenoid in the transmission CLICK. Does it? If solenoid stuck it tells the transmission the throttle is floored and to stay in the lowest gear possible. Move the shifter slowly through the PRND21 range. Are they all there? with separate clicks??? If not then the valve body may be stuck. Even with cloudy red fluid, it should make enough hydraulic pressure to drive it. If the filter is plugged it will usually whine badly from pump cavitation. You can buy new filters and a pan gasket as a kit and replace the ATF yourself rather that taking a bath at a shop. Because of the JATCO design, to flush the torque converter just pull one of the coolant lines off at the rad and start and idle long enough to pump out about one quart. Shut off and add one quart to the transmission and keep repeating until the ATF coming out is clear.... done. AT ALL TIMES DO NOT OVER FILL The automatic holds about 6 US qts so get enough for this job. (hail Mary...) Just starting and warming it up and repeatedly shifting it through the 'gears' may loosen up something stuck inside from sitting. 1 Quote Link to comment
rootbailey Posted March 26, 2018 Author Report Share Posted March 26, 2018 Thanks a lot I will start today and see what I can do and I do hear a click right before the pedal reaches the floor 1 Quote Link to comment
Charlie69 Posted March 26, 2018 Report Share Posted March 26, 2018 Can you manually shift the transmission. Start off in 1st then as neede shift to 2nd then as needed shift to 3rd. If transmission will change gears manually while driving then have the fluid & filter changed and flushed. Quote Link to comment
rootbailey Posted March 26, 2018 Author Report Share Posted March 26, 2018 I'm not sure if it does or not it's like it's in a higher gear but you have to push the gas pedal pretty hard for it to pick up Quote Link to comment
flatcat19 Posted March 26, 2018 Report Share Posted March 26, 2018 Drain fluid, replace filter and gasket. Fill with new to spec. Drive away. May take some running time to get everything to clear itself up. Just have to actually put in the work. Get off the internet. Quote Link to comment
datzenmike Posted March 27, 2018 Report Share Posted March 27, 2018 I'm not sure if it does or not it's like it's in a higher gear but you have to push the gas pedal pretty hard for it to pick up Not quite the same as not shifting. What is your top speed???? So start off with the selector in 1 and drive 1/2 throttle until at 15 MPH and shift to 2 you should feel a bump as it up-shifts. Does it? If yes keep going to 35 and shift into D. Again you should feel the shift into the next gear. Quote Link to comment
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