Auto trans sometimes slipping
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New User
Joined: Mar 2003
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Auto trans sometimes slipping
Can anyone out there advise?
But first, sit back and relax for a long (and boring) story.
My sister purchased a 1991 Aerostar with manual transmission (dreaded thing!) She (and me too for that matter) prefers automatics, so I traded the manual one (with some profit!) for a worn out auto; had the auto trans rebuilt and did the swapping. The transmission worked well… at first. The problem is that sometimes, but not all the time, when drive is selected and the car is standing still (for example waiting at a red light), the first gear seems to slip (as if it was in neutral), it only engages after I start pressing the gas pedal. This happens with the lever in any position, D, OD, 2, 1 and sometimes even in reverse. A few times I have had the impression that the transmission also slips when changing from first to second, but I’m not so sure. To make things funnier, I have found that when the car is moving with the selector in OD and I move it to N, the gear remains engaged as if it were still in OD.
Since it was a full swapping, I changed everything from the automatic vehicle to mine… with the exception of the engine’s computer.
The mechanic who did the rebuilding says the problem may be in the torque converter; but this was also rebuilt as part of the job. He also thinks there could be a problem with the pump. The guy is reliable enough, but I am paranoid, I don’t believe in diagnosis without proofs. I also suspect that the EEC doesn’t control the transmission properly, being from a manual car.
Everything is under guaranty and I have used the car only for a few days, but my sister needs it desperately; I would like to check all I can before having the transmission removed again.
Just some final words; I do have enough mechanical experience; but my knowledge of automatic transmissions is rather limited; and this is the first and only Ford I have ever had. (Call me snob, but I only drive Europeans!)
Besides the obvious, what else can I check? Suggestions?
Mark N.
But first, sit back and relax for a long (and boring) story.
My sister purchased a 1991 Aerostar with manual transmission (dreaded thing!) She (and me too for that matter) prefers automatics, so I traded the manual one (with some profit!) for a worn out auto; had the auto trans rebuilt and did the swapping. The transmission worked well… at first. The problem is that sometimes, but not all the time, when drive is selected and the car is standing still (for example waiting at a red light), the first gear seems to slip (as if it was in neutral), it only engages after I start pressing the gas pedal. This happens with the lever in any position, D, OD, 2, 1 and sometimes even in reverse. A few times I have had the impression that the transmission also slips when changing from first to second, but I’m not so sure. To make things funnier, I have found that when the car is moving with the selector in OD and I move it to N, the gear remains engaged as if it were still in OD.
Since it was a full swapping, I changed everything from the automatic vehicle to mine… with the exception of the engine’s computer.
The mechanic who did the rebuilding says the problem may be in the torque converter; but this was also rebuilt as part of the job. He also thinks there could be a problem with the pump. The guy is reliable enough, but I am paranoid, I don’t believe in diagnosis without proofs. I also suspect that the EEC doesn’t control the transmission properly, being from a manual car.
Everything is under guaranty and I have used the car only for a few days, but my sister needs it desperately; I would like to check all I can before having the transmission removed again.
Just some final words; I do have enough mechanical experience; but my knowledge of automatic transmissions is rather limited; and this is the first and only Ford I have ever had. (Call me snob, but I only drive Europeans!)
Besides the obvious, what else can I check? Suggestions?
Mark N.
Elder User
Joined: Feb 2003
Posts: 586
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From: Tottenham Ontario Canada
Auto trans sometimes slipping
If I read this right you put an auto tranny in a van that formerly had a manual trans. Obviously, you had to swap in or build a shift linkage for the auto.
Is it possible the shift linkage is out of adjustment so you're not properly shifted into *any* gear?
Is it possible the shift linkage is out of adjustment so you're not properly shifted into *any* gear?
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Auto trans sometimes slipping
Thanks for your reply. Everything from the auto vehicle went into mine, so I was safe regarding the proper linkage. I checked the adjustment, and it was in fact a wee bit out of position, which may explain why when I moved the lever to neutral it remained in OD. You are right, many times the obvious is the right answer.
I have an update on this case: reading trough other post in this board, posted by "myvan", he is describing a similar simptom, which developed after an oil change. As the story goes, the problem was sort of solved by adding a little extra trans oil. I checked the oil level in my car, it was about half way from the bottom mark to full in the "cold" section. The engine was at working temperature, the weather outside is at a nice 75 F; but the van had been driven only a few miles, so the oil was rather cool than warm. I decided to fill it up to the max mark; although it meant that when the oil would be hotter, it will read above maximum level.
I went driving around town today and the transmission is now working faultlessly! I'm not jumping in joy yet, lets see how it behaves from now on; but it does seem that the transmission likes running with a little extra oil, specially after the oil has been drained and replaced.
So this is my experience, I hope it will help other Aerostar owners. Be carefull not to overfill though, the manuals warn you against it under penalty of death; but it may be a matter of making certain than the oil level is at full after an oil change or transmission overhaul.
If all goes well, I will post an update in a few days confirming the results. Or else, crying out for help again!
Mark.
I have an update on this case: reading trough other post in this board, posted by "myvan", he is describing a similar simptom, which developed after an oil change. As the story goes, the problem was sort of solved by adding a little extra trans oil. I checked the oil level in my car, it was about half way from the bottom mark to full in the "cold" section. The engine was at working temperature, the weather outside is at a nice 75 F; but the van had been driven only a few miles, so the oil was rather cool than warm. I decided to fill it up to the max mark; although it meant that when the oil would be hotter, it will read above maximum level.
I went driving around town today and the transmission is now working faultlessly! I'm not jumping in joy yet, lets see how it behaves from now on; but it does seem that the transmission likes running with a little extra oil, specially after the oil has been drained and replaced.
So this is my experience, I hope it will help other Aerostar owners. Be carefull not to overfill though, the manuals warn you against it under penalty of death; but it may be a matter of making certain than the oil level is at full after an oil change or transmission overhaul.
If all goes well, I will post an update in a few days confirming the results. Or else, crying out for help again!
Mark.
Junior User
Joined: Feb 2002
Posts: 54
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Auto trans sometimes slipping
Hi Mark Two. Its myvan here.I caught your message in my other post
I thought I'd post a reply to your original post, you might see it sooner. But I had actually forgotten about the transmission slip, as it seems to have gone away. This was after adding a bit extra fluid over the full line. I read other peoples posts prior to that, and thought that it wouldn't work for me--different van, different years, different countries, etc. But I guess they are all the same. I wonder how many people have had overhauls for this reason! Mine seems to be back to normal. It stopped slipping right after adding the fluid, so I know that did it. i was almost ready to drop the pan and change fluid brands back to Motorcraft since I thought the transmission didn't like Quaker State. Of course there was the one reply that the new slippy and clean fluid would let the older, partly worn transmission slip more. But that does not seem to be the case.
Good luck with your transmission
I thought I'd post a reply to your original post, you might see it sooner. But I had actually forgotten about the transmission slip, as it seems to have gone away. This was after adding a bit extra fluid over the full line. I read other peoples posts prior to that, and thought that it wouldn't work for me--different van, different years, different countries, etc. But I guess they are all the same. I wonder how many people have had overhauls for this reason! Mine seems to be back to normal. It stopped slipping right after adding the fluid, so I know that did it. i was almost ready to drop the pan and change fluid brands back to Motorcraft since I thought the transmission didn't like Quaker State. Of course there was the one reply that the new slippy and clean fluid would let the older, partly worn transmission slip more. But that does not seem to be the case.Good luck with your transmission
New User
Joined: Mar 2003
Posts: 20
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Auto trans sometimes slipping
My van likes to slip on colder morning about once a month. It has a small leak that seems to get smaller, I've been using Valvoline high mileage with the stop leak. It seems to help. The van has got 167K on the ticker. Asides from the small tranny leak it runs stronger than ever. I have gotten into the habit of slightly over filling the trans and that definitely seems to fix the problem.
