1997 5R55E Reoccurring P0761 Fault

[97Sandbox]

Hello all,

A couple of weeks ago, I was driving my Explorer and as I merged onto an interstate, I got on the gas pretty hard (no worse than my usual though). Suddenly, it felt like the transmission downshifted two gears at once and the engine rpms jumped WAY up. I pulled my foot out of it immediately, but for the rest of the drive I noticed it wasn't going back into fifth gear. Soon, CEL came on and I got code P0761, "Shift Solenoid C Performance or Stuck Off." I figured the solenoid just wore out and would need replaced, not terrible I thought.

After considerable reading on this site (5R55E Valve Body Diary, Stairway to a Diary, and many others) I built up my confidence to not only replace the suspect solenoid, but replace all of the other solenoids, install the Superior Shift Kit (minus the thermo blocker and pressure riser), and also install a version of the Ford TSB blow-off valve mod. It all went pretty well and I have many members here to thank for that!

However, upon my first drive after the work (yesterday), I observed that while shifts were smoother and quicker feeling, and reverse engaged better than ever, I still couldn't get into fifth! Today I took the truck out again and CEL came back -- P0761 again.

Now I'm thinking I have to be missing something because I know it's a new solenoid. Can anyone help me uncover how I went wrong and where to go next?

 

[JK080]

It could have a broken overdrive band.

You could try to adjust it and if the adjuster turns more than 3 turns in the band is probably broken, if adjustment is good I would check the servo.

Do you have 2nd gear?

 

[97Sandbox]

Thanks James!

I'll check if I'm getting second later today.

Do you have a recommended method for loosening the lock nuts on the band adjustment studs? I took a crack at mine last night and the nut on the overdrive stud started deforming without backing off one bit. To access the intermediate stud, it looks like I'll need to detach the shifter linkage -- is that right?

 

[JK080]

I reread my last post and I said the intermediate band, sorry I meant to say the overdrive band. The overdrive band is responsible for 2nd and 5th.

The adjusters do have a tendency to be very rusty in some cases, sometimes its difficult to separate the jamb nut from the adjuster bolt too.

You could pull the pan again, you may be able to see the overdrive band anchor, from there you may be able to judge how much clearance is there, you can also compare it to the intermediate bands clearance. You can also air check the operation of the servo if you blow air into the exhaust hole in the pan rail.

 

[97Sandbox]

I took my '97 out for some analysis tonight and sure enough, there are only two distinct shift points from stopped to highway speed. Manual 1 and Manual 2 work fine, so I'm thinking I can rule out gears 1 and 3 having issues. I'm not sure how to tell if I'm missing 2 or 4 though. It runs about 3k rpm at 60 mph in the highest gear it will go into on level highway -- does that sound like 3 or 4?

Also a bit more background: while the vehicle has just over 200k miles on it, the transmission was rebuilt about 50k miles ago. It was before I owned the Explorer, but I have a detailed receipt covering all of the new parts that were used. When I redid the valve body last weekend, I didn't find anything alarming in the pan or VB, and the fluid was pretty clean (it was changed with the filter 20k miles ago). It did not smell burnt at all, which I had expected if the band wore out.

 

[97Sandbox]

I reread my last post and I said the intermediate band, sorry I meant to say the overdrive band. The overdrive band is responsible for 2nd and 5th.

The adjusters do have a tendency to be very rusty in some cases, sometimes its difficult to separate the jamb nut from the adjuster bolt too.

You could pull the pan again, you may be able to see the overdrive band anchor, from there you may be able to judge how much clearance is there, you can also compare it to the intermediate bands clearance. You can also air check the operation of the servo if you blow air into the exhaust hole in the pan rail.

Thanks for clarifying. The access to the OD adjuster does seem better -- linkage is still in the way, but maybe I'll find a way to get at it with the right combination of sockets and extensions. I will try to give it another go tomorrow.

I did take a ton of pics during the VB process, would I possibly be able to see the band anchor in one of those? Not like I'm expecting to eyeball the clearance in a dark image, but maybe something to check before I tear back into it...

Curious to try the servo air check too, but I'm not sure what you mean by pan rail (I'm new to this auto trans world).

 

[JK080]

Yeah I bet it's shifting 1 - 3 - 4, its missing 2nd and 5th. The overdrive band is not working for some reason.

Broken bands and failed servo pistons are the most common failures for this, these items can fail at any time, even new ones fail. I have had a couple of these bands fail on me after a rebuild so just because they may be new "ish" they can still fail.

The pan rail is the area the pan and gasket meet the case. There are two holes that vent the oil out from the servo area (highlighted in yellow), from what I remember you should be able to blow air into this hole and make the servo move to check the band. The best way to check to see if the servo is bad is to air check the servo through the passages that are under the valve body as shown in the picture below but that means removing the valve body. Then there is removing the servo from the side of the case and inspecting it.

 

[97Sandbox]

Thanks for that clarification and those helpful pictures! It makes sense to me now, but I probably won't have a chance to get back inside the pan until this weekend.

I'll try the band adjustment again tonight and come back with what I find out.

 

[97Sandbox]

With the shift linkage tugged out of the way and the truck on ramps, I came at the OD adjustment lock nut with a bigger wrench and broke it loose. It took about 2 1/3 to 2 1/2 turns until my wrench clicked at 120 inch-pounds. I backed the stud off two full turns and then held the it in place while I snugged up the lock nut (just used a box wrench, but my "calibrated" wrist says I had it within the 35-45 ft-lb range).

Took the Explorer back onto the interstate and . . . still no 5th gear. CEL came on quick this time (P0761 again), so I hopped off at the next exit and headed home.

Based on my understanding, I'm thinking these signs point to the band maybe being okay and the servo may actually be what's giving me grief -- does that sound right? Figuring this because it didn't take 3+ turns to torque the adjustment stud.

If these signs do point towards the servo, is the next step to drop the pan and air test, or should I jump ahead and pull the servo out for inspection?

 

[97Sandbox]

After reading the How to: - 5R55W transmission servo piston removal, I've been feeling inspired to pop off the OD servo cover and peek inside for damage. I'm not there yet (stuck servo cover), but I'll be running to the Farm & Home store for some Freeze-Off Super Penetrant shortly (per Solved - Frozen overdrive servo cover on a 5R55S transmission -- thanks for the tip @BrooklynBay ).

Here's what I did so far. All in all, it's been pretty smooth.

1. Located the cover. Access doesn't seem terrible and my exhaust won't come off without a full day of cutting and grinding, so I'm leaving it in place.

2. Brushed all around the snap ring with my DIY penetrant (ATF and solvent...I really need to pick up another can of b'laster).

Note: the shop that did the trans rebuild years ago must have cut out a relief slot to pry out the snap ring. Unfortunately, it's in the top left corner (hard to reach) so I didn't bother try to use it.

3. Pushed the cover in. I read about using a 3/4" wood dowel, but didn't have any wood like that, so I hammered in the ends of an aluminum tube instead -- it worked great.

4. With the pressure off the snap ring, I spun it to a good position and used two picks to compress it.

Would have been easier with offset needle nose pliers (better yet, real snap ring pliers) but I couldn't find mine. In all honesty, it wasn't that bad with the picks, took maybe 5-7 attempts and only scraped one knuckle in the process.
***Question: my snap ring has a helical shape now that it's out. Is that normal, or is mine deformed? Does that even matter (maybe it'll make it easier to slide back into the groove)?***

5. For good measure, I put some wood blocks in front of the cover in case the servo decides to jump out while I run to get freeze spray and penetrant.

All seems well for now, but any tips, tricks, suggestions, warnings, etc. are more than welcome!

 

[97Sandbox]

Well, shoot. Freeze penetrant was a no-go. I cleaned off all the residue after the freezing didn't work, then sprayed b'laster all around the servo cover. Now I'm letting that sit -- hopefully things loosen up. Might try freezing again later.

While I was under the trans taking a closer look, I noticed the cover sits in a tapered bore with a decent angle (i.e. it tapers down more abruptly than I expected). It also looks like I pushed the cover ~3/16" into the bore when I popped of the snap ring...did I push way too far and jam the cover in the bore?

It seems like I did.

Anyone have a recommendation to get the cover out via pressure from the inside? I've read some people had success with compressed air into the servo vent hole, others not. I also seem to remember reading someone just started the car and revved it til the servo shot out -- that does not sound like a good idea to me, but what do I know...

 

[JK080]

Try to tighten the band adjustment bolt all the way down it may push the cover out enough to make a difference.

 

[97Sandbox]

Try to tighten the band adjustment bolt all the way down it may push the cover out enough to make a difference.

Will that risk breaking the OD band? I read one thread where someone tried that and snapped the band before pushing the servo out (granted, the poster said he went 10+ turns!).

I'm more than willing to try, I just want to understand the risk. Should I tighten say, no more than 3 turns? No more than 5?

Thanks for your help!

 

[JK080]

Well stop if the cover doesn't move once it bottoms out with moderate pressure, just going to have to use your judgment here.

The other way would be to pull the pan again and try the vent hole trick or push on the exposed end of the servo piston. I cant remember if the valve body will be in the way to access the area needed.

You will have to use a flat screw driver and wedge it between the end of the servo and the lever the hold the band strut to try and push it out.

 

[97Sandbox]

Thanks for clarifying, I'll give it a shot!

I still haven't dropped the pan again, but I understand that I'll probably have to (RIP to all that fresh Mercon V) in order to have a way to hold the band strut in place. Hoping I don't have to drop the VB because I don't have any spare separator plate-to-case gaskets. Of course, if I need to order a new servo piston, I may as well be ordering (and waiting for) gaskets too.

 

[JK080]

The VB gaskets will be fine just be careful not to tear them, I have had a valvebody off and back on multiple times.

You do need to get rid of the cork pan gasket anyhow, neoprene is the way to go.

 

[97Sandbox]

Not a fan of the cork? I bought the Motorcraft filter and it came with that cork gasket. Unfortunately, the original filter bolt was gone and the one that was in there was too short for the MC filter. I bought a chepo CarQuest filter at Advance Auto just to get the tuck up and running and ironically that filter came with a rubber (maybe neoprene) gasket that's still sitting in the box on my work bench. If/when I drop the pan again, I'll put it back with that gasket.

 

[JK080]

Duraprene gasket, sorry.

4R44E 4R55E 5R44E 5R55E A4LD TRANSMISSION PAN GASKET OF DURAPRENE FIBER FITS '85+ FORD & MAZDA

4R44E 4R55E 5R44E 5R55E A4LD TRANSMISSION PAN GASKET OF DURAPRENE FIBER FITS '89+ FORD & MAZDA

www.transmissionpartsdistributors.com

Yeah we seem to see the cork gasket come back leaking. The rubber one from Advance can be a problem too, don't over tighten it.

 

[97Sandbox]

No reason to be sorry, you were right before!

My day job involves testing and qualifying elastomeric compounds, so I had the urge to do some digging. It seems Duraprene is just a name brand for a type of polychloroprene, aka Neoprene. Probably some proprietary compounding involved, but essentially all the same as far as we're concerned. It's known to have "good chemical stability and maintains flexibility over a wide temperature range." Sounds like a prime transmission gasket candidate to me!

Alright, time to take my engineer hat off and get back to wrenching...

 

[97Sandbox]

Well stop if the cover doesn't move once it bottoms out with moderate pressure, just going to have to use your judgment here.

I'm making progress, but not there yet. After heating the case surrounding the servo then zapping the cover with freeze spray, I turned the adjustment stud about 2 1/2 turns before it felt like it bottomed out.

The cover made its way just up to the snap ring groove...SO CLOSE!

Once I realized how close the cover was to coming out, I backed the adjuster stud off to where it had started and tried tapping on the top of the cover to see if I could tilt the top of the cover back into the bore enough so as to lift the bottom of the cover out to the point where I could sneak a pick in underneath the bottom edge (does that make any sense?). Seemed like a good strategy, unfortunately, the cover did not budge.

At least I know it's super close to coming out now. Tomorrow I'll drop the pan (VB too, if needed) and see what I can do to push on the servo from the inside.



As I called it a day, I had to stop and stare at my shifter opening, wondering how much I'd pay for a 4.0 SOHC+M5OD-R2 drive train from a wrecked 2000s Ranger...that may become my backup plan haha

All joking aside, this repair is really giving me a new appreciation for automatic transmissions. With the great resources and helpful members on this site, it's not as scary as I always imagined and I'm enjoying seeing what's actually going on in that mysterious box between my engine and driveshaft!