Slipping tranny 1995 Riv 3.8 supercharged

CHRISTINE is at it again! Driving along this morning perfectly normal. Suddenly the transmission gears aren't engaging and car doesn't go anywhere. Then it "whirs" a bit and with a "clunk" gears engage and car dives fine.  Park the car for about an hour. Upon leaving destination car drives fine again. Drove to store about three miles and parked again. Upon leaving next destination car drives OK and then gears do not engane again. Turned car of and restarted and  gears are engaging again. After about 1/2 mile gears aren't engaging. Stopped and checked fluid level and added fluid. Again started car and drove a short distance til gears aren't engaging.

Never had any issues at all with the transmission. This came totally out of the blue.

What puzzles me is the gears engage only after I turn car off and restart it. When not engaging, all forward and reverse gears don't engage. Engine is fine and acts as if in neutral.

I have never experienced this in any car I've ever owned. Anyone know of anything like this? I can be totally off base, but I'm thinking there may be an electrical issue of some sort, since after a full turn off and turn back on, something seems to "reset".

Help from anyone would be appreciated. I am not a mechanic, just a tinkerer that can usually figure things out. This one has me stumped, but that's been the case with "CHRISTINE" since I've owned her.

1) When was the last time you had transmission fluid changed and filter replaced? [your issue sounds like the torque converter is starved for fluid; when the fluid flows the car moves and vice-versa]

2) Have you ever had the transmission powerflushed, and when? [I like powerflushing but not just any mechanic can do it right; one can loosen debris that snags solenoids and/or blocks passages]

3) there was a Grand Prix forum thread on this back from 2013, the problem was a stripped drive shaft on the transmission fluid pump internal to the trans. http://www.grandprixforums.net/threads/76020-Transmission-won-t-engage

4) It would not be a waste of time to check for codes using a TechII. If the problem has any electrical symptom (some circuit's current is wrong etc.) you'll find out fast.

By the way how's that Lincoln. I liked my '95...

Albertj

Hi Albert,

I've never had the transmission fluid flushed. When I bought the car, the transmission (after a rebuild) only had about 40,000 miles on it. I've never had to add any fluid to it either.

When I checked, the fluid looked OK and had no bad smell.

The car is at the garage where they will be testing it. They have a Tech ll scanner.

The Lincoln is fine. Still getting used to it. Can't believe I've had it for a year already. I had to replace the engine computer, recently.  I've only driven it 650 miles or so. Longest drive was a couple weeks ago. Round trip from Baltimore to Rehobeth Beach DE. Drives like a dream and really takes off when asked to. It's like having a living room with a passing gear!

Thanks again for your help.

Harvey C

designer1962 wrote:

Hi Albert,

I've never had the transmission fluid flushed. When I bought the car, the transmission (after a rebuild) only had about 40,000 miles on it. I've never had to add any fluid to it either.

When I checked, the fluid looked OK and had no bad smell.

The car is at the garage where they will be testing it. They have a Tech ll scanner.

The Lincoln is fine. Still getting used to it. Can't believe I've had it for a year already. I had to replace the engine computer, recently.  I've only driven it 650 miles or so. Longest drive was a couple weeks ago. Round trip from Baltimore to Rehobeth Beach DE. Drives like a dream and really takes off when asked to. It's like having a living room with a passing gear!

Thanks again for your help.

Harvey C

It's GREAT that your garage has a TechII, that will help.

How many miles on the car now? Reason I ask -- I was just thinking, I had my transmission rebuilt long ago (at about 99K miles, now have 330+K). Took it back to that rebuilder for a maintenance fluid change (at 200-some K miles). I had changed the fluid to Dex 6. The shop boss (who rebuilt it) was out, I asked for Dex 6, told him it was already changed BUT his sidekick refilled it with Dex 3 and an additive anyway. The transmission grenaded pretty much like yours about 22,000 miles later. The reversion to Dex 3 killed the frictions, they fragged, and the TC and solenoids did not like the fragments. It failed on me suddenly while I was on a business trip, fortunately close enough for a tow to the shop... Back at the transmission shop, we all had a talk (ahem), the shop made good, his sidekick is still at the shop (just a little smarter now), and there will be no more fluid reversions ever, at least not at that shop. Experience shows: you can add Dex 6 to Dex 3 with impunity. NEVER REVERT or you get pretty much what happened to me. Epilogue to story: after the 2nd transmission rebuild the car still runs like a dervish and the transmission is full of Dex 6. Changed it once, it's about time for another change. As long as I keep Dex 6 in it I doubt I will have to talk to or about the transmission again except to admire and arrange fluid changes.

So what I'm getting at is, I am grabbing at straws now but wondering if is there a chance there was a fluid switch/reversion on your Riv before you got it? Maybe PO with dealer maintenance had switched to 6 and in the rebuild got switched back without replacing the frictions? You would/did not know?

As for that 95 continental I used to own, we drove it pretty much all the time in sport mode (the firmest transmission setting); pretty much all my driving is interstates.

Someone at a transmission shop suggested that the "MLP switch" could be the issue. It's what used to be called the "neutral safety switch" in the "old days". My faithful garage has not gotten back to me yet. (Going on two weeks!) I'll update whenever the diagnosis is done.

No codes are showing at all after scanning. According to the garage they had no shift issues with the car at all. I haven't picked it up yet, so I don't know if it has healed itself or not.

Maybe they did not drive it long/far enough to duplicate the failure.