Irregular transmission shifting
Thread Starter
|
Freshman User
Joined: Jan 2005
Posts: 43
Likes: 0
Irregular transmission shifting
Up until a few weeks ago, the transmission at least still worked (although you would have to rev it up and then let off the gas for it to shift until it warmed up).
A few weeks ago, just driving along, it all of a sudden slipped out of gear. Now, I can't drive it anywhere. When I put it in gear, it sounds like it engages, but it just makes a whirrrrring sound. If I give it some gas, the whirrrrring sound quiets down a little, and the vehicle very slowly moves (I'm talking about one inch per 30 seconds).
The fluid level is OK and it still looks pretty red. About 2 months ago, when it didn't want to shiift in the cold weather, I changed the fluid and filter. When that didn't make it any better, I changed the vacuum modulator.
I really appreciate any suggestions. The vehicle has been sitting for a few weeks now. Not sure what to do with it. Is it possible that just the pump is gone, and that the rest of the tranny, torque converter, etc. is still OK?
kitsamson2000 <kit.samson@sbcglobal.net> wrote:
A few weeks ago, just driving along, it all of a sudden slipped out of gear. Now, I can't drive it anywhere. When I put it in gear, it sounds like it engages, but it just makes a whirrrrring sound. If I give it some gas, the whirrrrring sound quiets down a little, and the vehicle very slowly moves (I'm talking about one inch per 30 seconds).
The fluid level is OK and it still looks pretty red. About 2 months ago, when it didn't want to shiift in the cold weather, I changed the fluid and filter. When that didn't make it any better, I changed the vacuum modulator.
I really appreciate any suggestions. The vehicle has been sitting for a few weeks now. Not sure what to do with it. Is it possible that just the pump is gone, and that the rest of the tranny, torque converter, etc. is still OK?
kitsamson2000 <kit.samson@sbcglobal.net> wrote:
<TT>
You didn't say how your transmission failed so I'm just guessing from your sequence of events that it was due to a failed ATF pump. On a typical transmission, the pump is on the input shaft so there's only one way to replace it. Also the reason why towing has to be done with rear wheel lifted because the input shaft only spins (and turns
the ATF pump) when the motor is running. Otherwise everything in the trans is spinning without lubrication.
I've known it to happen that when there's a sudden change in ATF consistency - as in replacing it after a loooong time with the whole trans by now adapted to thicker/dirtier fluid - the ATF pump finds itself incapable of delivering the correct working pressure because it's suddenly dealing with a less viscous fluid.
Not saying that this happened to yours but you did have all the symptoms.
Kit
--- In fordexplorer@yahoogroups.com, John Denlinger <hu5ker555@y...>
wrote:
I had the exact same problem with a 94. Changed fluid and filter,
changed vaccuum modulator, still didn't work. Then, about two weeks later, the tranny gave out completely. Haven't decided what to do with it, but I'd be interested if someone can explain what's going on.
> Kit Samson <kit.samson@s...> wrote:Off hand I'd suspect a defective vacuum modulator for the '94. Either the modulator itself is defective, or the vacuum source from the intake manifold
has been compromised. The metal tube attached by bracket on top of the upper intake body with a short rubber hose leading to one of the vacuum nipples supply vacuum to the mod. Undo the hose, attach a vacuum pump and see if it holds. It that's not it, you could consider replacing the ATF & filter (especially if you haven't done so for a long time). Fluid color on the dipstick is not the best indicator. The amount of sediment you might find in the pan could still surprise you. When this happened to mine, the culprit was ATF sediment in the pan. Apparently and as temp went up, the sediment would dislodge and get into the valve body upsetting piston movement.
On the '95, - I could be wrong because it's entirely different. I
think shifting is controlled by solenoids that are inside the valve
body. There's a control module that governs the transmission somewhere inside the passenger cabin that you can test for fault codes. Pick up a CHILTON or HAYNES manual from your local auto supply to find out where that module is and how to test it. In your case, it surely won't hurt to also replace the ATF. The solenoids in the valve body only modulate fluid flow to the pistons. It's still the pistons that activate the shifts so sediment can still get in their way.
>
> Hope this helps.
>
> Kit
>
> __________________________________________________ _____________
__
>
> Message: 1
> Date: Sun, 06 Mar 2005 05:53:29 -0000
> From: "eighta2001" <eighta@v...>
> Subject: Re: transmission shifting irregular
>
>
In fordexplorer@yahoogroups.com, "k2bio" <BlueFlash@c...> wrote:
Any DIY'ers in this group? A week ago my 95 explorer suddenly started failing to automatically upshift (2-3 & 3-4). However it upshifts if I let off on the gas. It's acting like you'd expect if you
floored it, holding in a lower gear. Since it will actually shift, I conclude that there is nothing mechanically wrong. Rather it's something in the electronic control system. I've tried the speed sensor, and the throttle position sensor. They both seem OK. Any experience?
Regards,
Don
</TT>
You didn't say how your transmission failed so I'm just guessing from your sequence of events that it was due to a failed ATF pump. On a typical transmission, the pump is on the input shaft so there's only one way to replace it. Also the reason why towing has to be done with rear wheel lifted because the input shaft only spins (and turns
the ATF pump) when the motor is running. Otherwise everything in the trans is spinning without lubrication.
I've known it to happen that when there's a sudden change in ATF consistency - as in replacing it after a loooong time with the whole trans by now adapted to thicker/dirtier fluid - the ATF pump finds itself incapable of delivering the correct working pressure because it's suddenly dealing with a less viscous fluid.
Not saying that this happened to yours but you did have all the symptoms.
Kit
--- In fordexplorer@yahoogroups.com, John Denlinger <hu5ker555@y...>
wrote:
I had the exact same problem with a 94. Changed fluid and filter,
changed vaccuum modulator, still didn't work. Then, about two weeks later, the tranny gave out completely. Haven't decided what to do with it, but I'd be interested if someone can explain what's going on.
> Kit Samson <kit.samson@s...> wrote:Off hand I'd suspect a defective vacuum modulator for the '94. Either the modulator itself is defective, or the vacuum source from the intake manifold
has been compromised. The metal tube attached by bracket on top of the upper intake body with a short rubber hose leading to one of the vacuum nipples supply vacuum to the mod. Undo the hose, attach a vacuum pump and see if it holds. It that's not it, you could consider replacing the ATF & filter (especially if you haven't done so for a long time). Fluid color on the dipstick is not the best indicator. The amount of sediment you might find in the pan could still surprise you. When this happened to mine, the culprit was ATF sediment in the pan. Apparently and as temp went up, the sediment would dislodge and get into the valve body upsetting piston movement.
On the '95, - I could be wrong because it's entirely different. I
think shifting is controlled by solenoids that are inside the valve
body. There's a control module that governs the transmission somewhere inside the passenger cabin that you can test for fault codes. Pick up a CHILTON or HAYNES manual from your local auto supply to find out where that module is and how to test it. In your case, it surely won't hurt to also replace the ATF. The solenoids in the valve body only modulate fluid flow to the pistons. It's still the pistons that activate the shifts so sediment can still get in their way.
>
> Hope this helps.
>
> Kit
>
> __________________________________________________ _____________
__
>
> Message: 1
> Date: Sun, 06 Mar 2005 05:53:29 -0000
> From: "eighta2001" <eighta@v...>
> Subject: Re: transmission shifting irregular
>
>
In fordexplorer@yahoogroups.com, "k2bio" <BlueFlash@c...> wrote:
Any DIY'ers in this group? A week ago my 95 explorer suddenly started failing to automatically upshift (2-3 & 3-4). However it upshifts if I let off on the gas. It's acting like you'd expect if you
floored it, holding in a lower gear. Since it will actually shift, I conclude that there is nothing mechanically wrong. Rather it's something in the electronic control system. I've tried the speed sensor, and the throttle position sensor. They both seem OK. Any experience?
Regards,
Don
</TT>
Thread
Thread Starter
Forum
Replies
Last Post
Jimerin
Clutch, Transmission, Differential, Axle & Transfer Case
9
Mar 26, 2016 07:50 AM
Jim Pivonka
1967 - 1972 F-100 & Larger F-Series Trucks
24
Jul 18, 2010 08:01 AM
hu5ker555
Explorer, Sport Trac, Mountaineer & Aviator
4
Jan 25, 2005 09:12 AM
Nate1
Clutch, Transmission, Differential, Axle & Transfer Case
3
Oct 25, 2003 09:58 AM
