94 explorer wont move in any gear

[paullywallyboy]

Hey there. I'm new and still finding my way around. Friend was driving home when she heard a noise and trans suddenly would not move in any gear. I got a gauge hooked up today. It runs about 70 lbs in p n od d 2 and 1. It runs a little higher in r. Pressure doesn't seem to change at high idle but will go up to 300 at wot then drops back to 70. Any ideas or suggestions will be appreciated.

 

[natenkiki2004]

Sounds typical of the A4LD hard parts grenading. Many have had this issue, including mine. I wish I had a list of parts for you but the previous owner of mine had it fixed. There's a lot of parts that can be upgraded. An upgraded A4LD is no slouch, as long as you're willing to put the time and/or $$ into it.

 

[FR-425]

Sounds like it popped a servo.

 

[paullywallyboy]

Thanks. Is there a way to check servo's?

 

[FR-425]

You already did.

Time to disassemble.

You can get at the rear servo without pulling the trans and Maybe able to do the front servo with the cats out of the way, not sure on that one.

Unfortunately you will be spending a lot of time on a shot in the dark.

You may as well pull the trans after dropping the pan to look for chunks of metal.

 

[FR-425]

It's possible that the sound she heard was the filter popping off and now it's starving for fluid as the filter is also the pickup tube.

Assuming you have a 4x4 make sur you get the 4x4 filter. The pickup tube is longer, the 4x4 has a deeper pan than the 2x4.

Best case scenario when you here a "noise" followed by no gears.

 

[paullywallyboy]

OK. Thanks guys! Looks like its time to pull the pan or buy another explorer.

 

[paullywallyboy]

Someone suggested that the splines in the torque converter stripped. Would that cause it not to move in any gear and still build pressure?

 

[natenkiki2004]

Engine bolts to the flex plate, flex plate bolts to the torque converter, power is transferred from the torque converter into the input shaft, the splines you're talking about. If the splines were stripped, it wouldn't be able to drive the pump or anything other than the torque converter. I would think it would also cause a helluva racket as the broken/worn splines are grinding on each other.

Not to mention, I haven't seen anyone ever mention stripping out torque converter splines on an A4LD. It's usually the hard parts inside or the clutches that go.

Drop the pan & take a look if there's pieces. I don't honestly think the filter popped off, there's bolts that hold it in and unless someone was in there before and didn't tighten them, chances are good that it's still in there securely. Plus, there's suction on the filter, not pressure. Plus, you wouldn't hear any noise, the engine would just go back to idle and you'd lose driving gears (as there isn't any fluid to build pressure in the trans to apply the clutches).

If you do need a new trans, you can go for a junkyard one while you have the original one out and upgrade/rebuild it. That is, if you want to keep the vehicle. That would buy you time to gather all the parts and build it right, even if you're on a tight budget. Or... buy another Explorer and use this one for parts.

 

[paullywallyboy]

Haven't got the pan off yet. Got better thing to work on.
I was under the impression that the shaft ran something else besides the pump but I have never had an a4ld out. I believe c6 pumps are ran by flat sides on the torque converter. Figured they were the same.

 

[paullywallyboy]

I just pulled the pan. Fluid is clean and bright. It should be though as it has been through a few modulator this last year. There are no big chunks in the pan either. Just some metal dust on the mag strip. Any idea on what to check next. Seems like it has good pressure on idle but doesn't hold on wot.

 

[FR-425]

Check out this thread about the bent broken "z link"

If it's bent/broken or popped out of place the valve slide will not be in the right spot as you move the gear selector.

This usually happens when you have to pull really hard to get it out of park on a steep hill.

http://www.explorerforum.com/forums/showthread.php?t=155599

 

[paullywallyboy]

Check out this thread about the bent broken "z link"

If it's bent/broken or popped out of place the valve slide will not be in the right spot as you move the gear selector.

This usually happens when you have to pull really hard to get it out of park on a steep hill.

http://www.explorerforum.com/forums/showthread.php?t=155599

Thank you. I read about it previously and it looks to be fine. I was hoping it would be that simple.
It seems like it is not holding pressure. As if something is popping off when in give it throttle. I have read about pressures a little but don't know if that is normal or why it would do that?

 

[FR-425]

This may sound silly but maybe the rear diff is grenaded and the drive shaft is actually turning.

Pop it in gear and have a look to see if the drive line is turning.

Derp, I forgot you already have the pan off. ...

 

[paullywallyboy]

This may sound silly but maybe the rear diff is grenaded and the drive shaft is actually turning.

Pop it in gear and have a look to see if the drive line is turning.

Derp, I forgot you already have the pan off. ...

Park holds on steep incline so I figured rear diff and transfer are good.

 

[FR-425]

yup

The next step would be to pull the valve body and see if the gasket is blown and check each valve bore one at a time. If the gasket is blown out you can assume that's where the pressure loss is at and leave the valves alone.

However while your in there there are some upgrades you may want to do.
The power valve for sure: replace with the Sonnax power valve.

These guys have all the a4ld bits:

http://www.sonnax.com/units/91-A4LD

I would check the main oil (power valve) first. then the manual valve.

Here's the exploded view: never mind the red arrow (different symptoms)

 

[paullywallyboy]

Thank you for the info and diagram. That will help. Should I also get a shift kit for it?
And on another note I just purchased a 1993 explorer with 150k on it. Tranny and engine seem ok. I think they quit driving it because the ac froze up. Trans shifts pretty soft. So soft I couldn't tell if it was hitting all the gears. Anyway , I plan to do a service on the trans. Should I put a shift kit in while its apart and should I take it somewhere and have it flushed or is there another way to get all the fluid out?

 

[FR-425]

No and no.

Flush is a bad idea and so is the shift kit. With the Sonnax valve it'll shift very firm already any more than that and they just bang shift to hard.

On the mushy feel'n trans put it in drive not overdrive and you'll see a difference. The power valve in these have a low and high pressure position, in overdrive it is low pressure for a smoother shift. In drive it'll shift faster and firmer and at a higher rpm. Sort of a built in shift kit.

And yet another diagram: Shift sequence..

This shows the main flaw in the A4LD and that is that when in overdrive the band is engaged but not the sprag (one way clutch) putting all the stress on the overdrive drum (which is stamped steel) so when you downshift at full power it hits the sprag without any hydraulic clutch to cushion the blow and bang you smash the OD drum or blow the front seal out.

A sprag or one-way clutch is like a bicycle hub, spins free one direction, clickity, clickity, but turn it the other way and it instantly grabs. It is a mechanical clutch not hydraulic.

This is why Ford flat out says DO NOT TOW IN OVERDRIVE. also not recommended for any lead foot round town play or off road. Me personally I never use overdrive unless I'm on open highway and lightly loaded. Actually does better on gas around town this way.

Also notice that the reverse band is engaged only for 1st gear "manual" to further strengthen 1st gear for serious pulls, that's actually a nice trick. (primary nasty stuff gear) So for off road use manual 1st as your main choice rather than just tool'n around in drive.

Never mind the highlights found the pic this way:

 

[FR-425]

Catching breath now. .. .:frospecta

 

[FR-425]

That all being said if you still have slippery shifts in drive it's not broke it just means the bands need adjusting.

Simple to do:

http://www.explorerforum.com/forums/showthread.php?t=158160