My A4LD is slipping from first to second gear.

[95starRWD]

Hey all, I have a 1995 Ford Aerostar 3.0L RWD with 140k miles with the A4LD Transmission.
work to date includes;
power steering pump, serp belt, idler pulleys, water pump, thermostat, plugs, wires, cap, rotar, distributor, ignition coil, PCV valve, iacv, maf, vacuum lines, master cylinder and brake booster, calipers, all suspension and brake components, driveshaft rebuild, rims and tires.

was noticing a little hesitation going into park and drive. Nothing serious and no issues shifting (maybe a “medium” shift 1st to second here and there but it’s an older van didn’t think much), but my fluid was dark so i figured I’d do a trans filter and modulator change. I did just that and checked my fluid level, I have read on this forum that the dipstick doesn’t read correctly and to add roughly half a court past the fill line but to be safe at first I filled it to the fill line. Checked on a level surface in park. First drive I went with it the trans tries to go to second, hesitates, then goes into second. Ok other shifts are fine. Downshifts are fine as well when I give it some gas. I drove back, checked fluid level, added the extra half court, and drove the van for about half an hour going through the gears. Issue will not go away. Also checked nothing was leaking or loose. Only a hesitation first to second.

my thoughts are I might not have tightened the filter bolt to spec. Or an issue w O rings on it. I made sure to put them on and make sure they were seated correctly, as well as make sure they worked into the holes evenly and okay without forcing it/slamming it.

Maybe modulator issue? It’s brand new and seemed straight forward to replace, take the retaining bolt out pop out the old one and pop in the new one, then hookup line. Am I missing something on that?

my other thought is the bands may need adjusted?
or that first to second was a pre existing issue and the fluid change exaggerated it. A4LD things lol.
I’ve driven it to work and seems like it just starts in second or is inly in first for a brief moment then continues from second. Took about 4QT after putting new filter on.
just wanted to get other peoples thoughts on it who have more experience than me. I’m only 20 this is the first vehicle I’ve worked on with an A4LD.

 

[BrooklynBay]

Did you remember to transfer the pin in the modulator from the old one to the new one?

 

[95starRWD]

Did you remember to transfer the pin in the modulator from the old one to the new one?

So from yesterday a decent bit has happened. When I removed the old one I didn’t have a pin abs didn’t know I should’ve. I swapped the old mod in, same issue. Put new one back in with a pin I made from a drill bit but same issue. Used the specs shown in the photo I’m posting I found from the Ford-trucks forum. I also took it apart, double checked the filter and torque specs on pan, and made sure to check there was no trans fluid left in the vacuum line (why I replaced it, there was fluid in it) all with the same issue. It slips mostly 1st to second but after all this from todsy it took a lot more gas to move in reverse snd the slipping also occurs downshifting. Just seems like it over revs and doesn’t know when to shift. No sludge or metal shavings in pan/fluid. Fluid is old but not burnt and doesn’t have any debris. Not sure what it could be down. I know it has to be something I touched so I’m leaning towards the modulator/pin. Should I try going to a junk yard or ordering it online? I’m not sure what else to do other than plan rebuilding but I don’t think it needs it at 138k with no trans issues till I messed with it unfortunately. Thankyou for the reply

 

[95starRWD]

 

[BrooklynBay]

Did you check the hose on the vacuum line to see if there's sufficient vacuum? Sometimes the hose develops cracks or gets stretched out, then it leaks.

 

[95starRWD]

i visually inspected it all the way to the vacuum tree. My slipping issue was immediate after I replaced my filter snd replaced my modulator.

 

[95starRWD]

So trans was okay and shifted good with no “hesitation or slipping” before the filter change and modulator change. Fluid was in line upon removal. It’s adjustable but even when I put the old one back in to see if adjustment was off it still did it. Is there a way to test my vacuum pressure? I feel like it has to be something vacuum related but my only trans experience is flushing and filter changes. I’ve read valve body’s are a common issue, would that be hard for someone to rebuild w no trans experience? I’ve done all the work to this van on my own so far, I have my grandfather to help me who isn’t a mechanic but worked on his farm equipment. To me it doesn’t feel like the trans is giving symptoms of catastrophic failure or hinting at it. It drives the same on the highway. Still have power to it. It’s mainly the 1-2 hesitation where it half engages and doesn’t know when to shift, and if I floor it it doesn’t know what to do. Otherwise 2-3-O is okay. Doesn’t feel 100% but doesn’t feel like it’s about to blow up and still gets up to 75 in the highway just fine. Thankyou for the help

 

[Josh P]

Have you tried putting the sifter in 1st gear starting out then shifting to D?

 

[BrooklynBay]

Auto parts stores sell vacuum gauges but that might not be the issue. Sometimes a sticking governor could cause a delayed 1 - 2 shift while it's cold but slowly goes away as it warms up. Does this happen only when it's cold or any time?

 

[95starRWD]

I have tried manually shifting 1-2-D-OD and get a better but similar issue. Still over revs into gear. The van has always ran a little cold, just under O and never moves. Have done tstat water pump and some coolant lines. But anyways it is consistent no matter engine temperature. Outside temp has been 20-50* and hasn’t seemed to have any affect so far. Should I just start planning on a rebuild? I’ve found quite a few videos online and manuals on how to rebuild them and would like to try that route as I’m tight on money at the moment. Van is drivable and unfortunately my daily so I’ll have to plan a weekend. I just can’t see how it would go bad after a new modulator abs filter change. Planning on a hard rebuild as well abs new torque converter I’m assuming

 

[BrooklynBay]

Try adding some Lubegard additive. You could try Lucas but only a little bit (not a whole bottle). Don't try both at once.

 

[95starRWD]

So I tried that last night w Lucas abs half a bottle. Definitely a little better but still same issue. I don’t know how a modulator and filter change could blow a trans, no metal at all in pan no signs of anything bad but I’m guessing I’ll have to try rebuilding it

 

[BrooklynBay]

Try rebuilding the valve body before you do a whole new rebuild. Some places like Central Valve Bodies are able to test your old valve body. You could add Sonnax parts to your valve body.

 

[Turdle]

Might be a silly suggestion, but, I would sure stick the old modulator on. You might have a bad new part. I never trust a new part 100%

 

[95starRWD]

okay thankyou for the suggestions. To remove the valve body do I have to drop the trans? Also, I did try the old modulator and had the same result. Just while thinking of it I used Mercon V but did not flush the system. Could the mix of Mercon V and whatever was in the trans originally cause this? Just a thought. But from what I know Mercon V is approved to use in Mercon vehicles (without transfer case) because Ford discontinued Mercon.

 

[BrooklynBay]

You could reach the valve body when you remove the pan. Newer Fords use Mercon V. These transmissions use Dexron III or regular Mercon.

 

[95starRWD]

okay thankyou for the help Brooklyn. Is the valve body something that can be rebuilt on your own? Or something I should take somewhere for rebuild. Also, just because I’m not sure of how it works, is the modulator tied into the valve body system? Would the modulator being bad for long enough cause an issue with the valve body? I’m just puzzled because it shifted fine/completely different than the symptoms I have now. Seems like a completely different trans

 

[Turdle]

Yeah, from what I understand mercon V is slippery. You need something tighter like dex III

 

[Josh P]

There are a few posts here, where people have changed transmission fluid that was long overdue and the transmission failed shortly after. It is also possible an unrelated problem just appeared right after changing the fluid.

 

[BrooklynBay]

We have several threads on rebuilding an A4LD & valve body.