Tweet
Hello everyone! I'm new to the board and I am seeking advice/suggestions for an issue I am having.
I have a 1992 Buick Century 3.3L V6 with a 3T40 (TH125C) 3 SPD FWD automatic transmission. 116,600 miles on it. Couple of weeks ago, I pulled into my parking spot at the apt and didn't like how I pulled in. I threw the car in reverse, but much to my dismay nothing happened!
Specifically, the problem is this: when cold, shifts into reverse solid, every time. As the car warms up, reverse becomes slow to engage, until disappearing entirely when the engine and tranny are fully warmed up. All other gears still work fine, shift when they are supposed to, and there is no slipping. In fact, I can't say I've ever had any slipping.
I pulled out the service manual and started doing some research online to find out what might be causing this.
1) I've read that the Lo and Reverse Oil Pipe under the pan enters into the tranny case at the Lo-Reverse clutch via an O-Ring, Cup Seal and a back-up washer. I've heard that if the O-Ring is starting to go bad then you can lose reverse.
It was about time for a transmission fluid change anyway so I decided to check it out. Fluid came out a brownish-red, kind of like Cherry Coke, which I'm told is normal when it's old. No particles or flash in the fluid and no burned smell either, so that was good. Dropped the pan and again, no flash or particles in the fluid or on the magnet. (bunch of sludge on the magnet, though).
The Lo-Reverse pipe came out easily enough. The washer on the end did not look nicked or cracked and it was still pliable with a bit of firmness to it. Couldn't really see the Condition of the Cup Seal, but it looked OK. So I reseated the washer, O-ring and pipe, changed the filter, put the pan back on and filled her up. Shifts a lot nicer with the new fluid, but problem still exists.
2) One source suggested that the problem is the reverse booster valve in the valve body. With time, it can become worn and cease to function correctly, not supplying enough pressure to successfully engage reverse.
I'm inclined to believe this may be part of the problem if not the whole problem. Sometimes, when the car is fully warmed up, I can shift into reverse and if I wait around 10 seconds or so, reverse will engage. Once it has engaged, it sticks and holds well. If I shift into Park or Neutral and a couple seconds later back into reverse it engages again instantly. Shifting to drive and back causes it to delay a few seconds. If I shift into Park, Neutral, or Drive for more than a couple seconds and then back into Reverse, reverse may take upwards of 10 seconds again to engage or not at all. So it sounds like there's a pressure related issue.
So I come before you good folks seeking wisdom and advice. Any pointers would be greatly appreciated. Thanks much!
-Kevin
I have a 1992 Buick Century 3.3L V6 with a 3T40 (TH125C) 3 SPD FWD automatic transmission. 116,600 miles on it. Couple of weeks ago, I pulled into my parking spot at the apt and didn't like how I pulled in. I threw the car in reverse, but much to my dismay nothing happened!
Specifically, the problem is this: when cold, shifts into reverse solid, every time. As the car warms up, reverse becomes slow to engage, until disappearing entirely when the engine and tranny are fully warmed up. All other gears still work fine, shift when they are supposed to, and there is no slipping. In fact, I can't say I've ever had any slipping.
I pulled out the service manual and started doing some research online to find out what might be causing this.
1) I've read that the Lo and Reverse Oil Pipe under the pan enters into the tranny case at the Lo-Reverse clutch via an O-Ring, Cup Seal and a back-up washer. I've heard that if the O-Ring is starting to go bad then you can lose reverse.
It was about time for a transmission fluid change anyway so I decided to check it out. Fluid came out a brownish-red, kind of like Cherry Coke, which I'm told is normal when it's old. No particles or flash in the fluid and no burned smell either, so that was good. Dropped the pan and again, no flash or particles in the fluid or on the magnet. (bunch of sludge on the magnet, though).
The Lo-Reverse pipe came out easily enough. The washer on the end did not look nicked or cracked and it was still pliable with a bit of firmness to it. Couldn't really see the Condition of the Cup Seal, but it looked OK. So I reseated the washer, O-ring and pipe, changed the filter, put the pan back on and filled her up. Shifts a lot nicer with the new fluid, but problem still exists.
2) One source suggested that the problem is the reverse booster valve in the valve body. With time, it can become worn and cease to function correctly, not supplying enough pressure to successfully engage reverse.
I'm inclined to believe this may be part of the problem if not the whole problem. Sometimes, when the car is fully warmed up, I can shift into reverse and if I wait around 10 seconds or so, reverse will engage. Once it has engaged, it sticks and holds well. If I shift into Park or Neutral and a couple seconds later back into reverse it engages again instantly. Shifting to drive and back causes it to delay a few seconds. If I shift into Park, Neutral, or Drive for more than a couple seconds and then back into Reverse, reverse may take upwards of 10 seconds again to engage or not at all. So it sounds like there's a pressure related issue.
So I come before you good folks seeking wisdom and advice. Any pointers would be greatly appreciated. Thanks much!
-Kevin
Comment