94 A4LD - No Second Gear

[PDH]

My son's 94 Explorer was overheated when a friend borrowed it. Warped the heads and put coolant in the exhaust and engine oil. I rebuilt the engine. When I completed the rebuild, I ran an OBDI tester and it told me the tranmission OD lock up solenoid circuit was amiss. I put an Ohm meter on the solenoid and obtained infinite resistance. The OD solenoid had failed. Since I had to drop the transmission pan to change out the OD solenoid, I also removed and rebuilt the valve body with the parts and pieces recommended by Glacier991. I replaced both the 3-4 solenoid and OD solenoid, installed the Transgo shift kit and the other recommended items.

I also adjusted the bands as described by BrooklynBay.

Put the tranny back together using an inch-pound torque wrench to install the valve body. I now have no second gear. The vehicle has 157,000 miles on it. The transmission was rebuilt at about 135,000 miles by a shop in Anchorage, Alaska.

Any ideas or suggestions for trouble-shooting this? When I dropped the pan the transmission fluid looked OK and no parts or pieces in the pan. I hadn't driven the car prior to the engine overheating but my son didn't mention that second gear was out.

Should I try readjusting the bands again. Tighten down to 10 ft-lbs torque and then back off 2 complete turns, correct?

Any questions please ask. Your help would be appreciated. Thanks.

 

[BrooklynBay]

Welcome to this forum! The 3-4 shift solenoid is the overdrive solenoid. The other solenoid is the TCC lock up. Did you see if the band adjusters got out of place in the transmission when you dropped the valve body? It's possible that the servos got fried from excess heat. I would also see if the modulator got damaged from the heat. Check the vacuum line for leaking fluid.

 

[PDH]

BB, thanks for the welcome and for your reply.

The TCC lockup solenoid was the one that faulted open on this tranny. The one located to the front of the tranny on the passenger side of the vehicle. I replaced both the TCC lockup and 3-4 shift solenoids with a kit from transmissionpartsusa.com.

I did pull the rubber vacuum hose off the modulator located on the passenger side of the transmission and saw no fluid in this hose.

I didn't look for the band adjusters when the valve body was removed from the tranny. I didn't move the vehicle or rotate the engine or drive shaft with the valve body or reverse servo removed from the tranny.

I adjusted the bands after rebuilding and replacing the valve body and reverse servo. It seemed like both bands were tightened about 3 1/2 turns before reaching 10 ft-lbs torque. I then backed off 2 complete turns and tightened the locknuts. I'll try readjusting these bands again tonight to double check my adjustment process.

The tranny takes off in first gear but runs up to 35-45 mph before shifting, and then shifts right past 2nd gear into 3rd gear, into 4th as best as I can tell. When I'm going 50 mph and try to downshift into 2nd gear, the vehicle just coasts like I placed the tranny in neutral. The rpms drop down to 1000 or less and if I step on the gas at that point, the engine just revs up as if in neutral.

With this information are you still thinking a fried servo problem? And does this involve a complete transmission pull to repair? Thanks again for your input. Great informational forum here which I'm glad to have found.

Paul

 

[BrooklynBay]

The servo could be replaced while the transmission is in the vehicle, but it's hard to get to. You have the catalytic converter, and a heat shield blocking it. The downshift problem might be the result of a misadjusted kick down cable. It's easy to adjust. Press the release button in the front of the cable where it meets the fire wall, and pull on it. Go inside, and step on the accelerator pedal. You will hear a clicking sound. It's now adjusted.

 

[PDH]

I will adjust the intermediate band again and try to make sure it's not broken. If it's broken I would expect it won't tighten up as I try to torque the adjustment bolt to 10 ft-lbs? Then I'll adjust that kickdown cable as suggested. If no luck at that point, I'll order up new intermediate and overdrive servos going the "ZC server retrofit" route as suggested by Glacier991. I'll order some new seals for the low-reverse servo. Maybe a new modulator also?

One member ran his vehicle in second gear only a short distance with the intermediate band snugged down to force-feed 2nd gear and confirm the band was still functional. I may try that to rule out a flawed intermediate band if I can work up the courage. I'll have to read his post again, but his symtoms were identical to mine and he had a bad intermediate servo, which is the direction you have pointed me in.

I've already had the catalytic convertor out of the vehicle so I'll replace the servos from beneath the vehicle if necessary. Sounds like a plan... I'll post an update on any progress or lack thereof.

 

[PDH]

Rest of the Story

OK, problem fixed and here's the story.

I first installed new intermediate and overdrive servos and upgraded to the ZC OD servo. I also replaced the vacuum modulator. The seals on both servos were stiffened up pretty bad but still functioning. It was relatively painless to install these parts from under the vehicle after removing the catalytic convertor. After this work I test drove the vehicle but still had no 2nd gear.

Next I dropped the transmission pan and pulled the valve body. I wanted to check valves 204, 211, and 216 since they control the 2nd gear shift. I found that I had improperly installed the spring in the 1-2 shift valve (valve 204) when I rebuilt the valve body. The spring was caught on the edge of the spool in a compressed state, rather than into the end of the spool as it should have been. After correcting this, I then replaced the o-ring seals on the low-reverse servo with some new D style seals. Then put it all back together and test drove again. Problem solved.

Moral of my story is if you rebuild your valve body - make sure ALL the valve spools move freely before putting it all back together.

Thanks BB for your recommendations and advice.

PDH

 

[BrooklynBay]

Thanks for the update!