How to: - 5R55E Rebuild DIY Diary | Ford Explorer Forums - Serious Explorations

  • Register Today It's free!

How to: 5R55E Rebuild DIY Diary


Well-Known Member
August 6, 2008
Reaction score
City, State
Houston, TX
Year, Model & Trim Level
Stock 97 4.0 EB SOHC

This thread started out as a diagnosis challenge, but has evolved into a rebuild guide of sorts. The rebuild section begins on the 2nd page, once I determined removal was necessary (i.e. not band adjustment or valve body issue). It is not quite as detailed as Glacier's A4LD rebuild, which is a good idea to read as well, but covers the main points with a lot of photos. The removal is fairly brief, but I did cover a few tricks on the re-install.

VEHICLE: 97 4.0 SOHC 4X4
TRANS HISTORY: Complete rebuild in 2005 at 125,000 miles; transgo jr. shift kit also installed; partial rebuild in 2006 at 129,000 miles - replaced reverse band, OD sprag and planetary
CURRENT SYMPTOM PROGRESSION: initially exhibited intermittent 2-3 shift flare which quickly worsened to regular occurence; next trans then exhibited only very slight engagement in D and R (high rpm's yielded very slight movement of vehicle); however manual 1 and manual 2 function correctly; no OBD codes
FLUID CONDITION: fluid level and color appear normal; no significant leaks detected; 45,000 miles since last fluid change

INITIAL THOUGHTS: based on the progression of symptoms (and extensive research on EF) it seems to me that the likely culprit is (in order of likelihood) something in the valve body, possibly a failing D/R servo, possibly a failing/failed reverse band

QUESTIONS: 1) does the fact that manual 1 and manual 2 function correctly (but D and R only slightly engaging) point to one malfunction/failure in particular? 2) the progression from the 2-3 flare to the more significant D/R partial engagement indicates to me a valve body failure, thoughts?

PLAN FOR REPAIR: have not yet removed pan, plan to remove and inspect valve body for obvious problems; either replace certain components or shotgun with a reman valve body; if no success proceed to servo inspection/replacement; if no success drop trans and rebuild/replace hard parts as necessary; initial rebuilds were done at shops, plan to do this myself, don't have the specific trans tools yet for rebuild so trying to minimize cost

Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!

Start with the basics before you make it into a rebuilding job. Check the band adjustment, EPC pressure, and the main pressure in each gear range.

Line Pressure Results

Main Line Pressure:
Gear..Idle...Fast Idle....WOT

EPC Pressure:
Gear..Idle...Fast Idle.....WOT

Does anyone have the pressure spec chart? I don't have the ATSG manual, and can't seem to find good info online (the torrent link here on EF is dead as well).
But... just looking at the numbers it seems pretty clear that my "D" pressure is unresponsive to WOT (i.e. way lower than it should be). This indicates to me a valve body problem, not an internal trans problem. Tranny gurus please chime in here. Any thoughts as to what specifically in the valve body is the likely culprit?

I should also note that the main line pressure blips down to 60-70 while switching gear selection before rising again. I observed a similar effect in the EPC pressure blipping down to 25 before rising again. I'm unsure if this is normal behavior and/or useful information.



I did actually find that image online, but it doesn't have the specs for P/N, 2, or 1 (assuming OD here is D). Any ideas as to culprits for low D pressure as observed through both mainline and EPC?

It probably has loose valve body bolts, and needs new valve body gaskets.

Part Compatibility

I've got the VB removed from the vehicle and have yet to find a smoking gun. All VB bolts felt the appropriate torque upon removal. Both separator plate gaskets appeared to be in good shape (no obvious signs of blowout), but that does not guarantee they were holding pressure adequately. Further inspection shows that the VB is all original, despite the prior rebuild invoice showing the Transgo shift kit (chalk up another one for the bad guys:thumbdwn:).

I'm still debating as to which VB upgrades to make, at a minimum I will do the FORD TSB (updated plate deleting hole #50 and replacing EPC relief/blowoff valve; part #:3L5Z7M203JA for the new valve only).

Though I'm a bit unsure as to part compatibility for the new plate. I have a 97 4.0 SOHC. For some reason, the TSB lists a separate plate number for the 97's (which does not have bonded gaskets), part #: F77Z-7A008-EB, which is also not in stock anywhere and appears to be discontinued.:scratch:

Does anyone know if the bonded gasket version for the the 98's and up is compatible (part #:1L5Z7Z490HA)? This version is readily available.

Conflicting Information

I have been looking at the parts list on all of the sites you mentioned BB. Trouble is, some resources show different P/N's for 97 (WIT, Ford TSB - neither is available though), and other resources show same P/N for 97-up (Transtar, bulkpart). I suppose barring any definitive "No they aren't the same" reply, I will order the '98 bonded gasket plate and compare to my existing OEM 97 plate. If there is more than just the hole #50 delete in terms of differences, I'll have to return the part.

Going forward (assuming the bonded plate is compatible), I'm thinking that I will just do the Ford TSB upgrade (which means new gaskets of course - possibly the source of my big problem) and see how that goes. I've tested the resistance of all solenoids, and they are within spec (without too many miles on 'em). If my problem is not solved, I'm leaning towards the Sonnax Zip kit (P/N 4R44E-5R55E-ZIP), which is fairly comprehensive.

I do have one other nagging issue to address. On disassembly, I noticed a few of the internal wires had cracks in the sheath. Now there isn't really any slack to allow for cut-splice-heat shrink. I'm thinking of using this product: It is a silicone based self-annealing tape - or something similar. The temperature range appears fine, just a little concerned with how it will react to the ATF. Is this a bad idea? Obviously if the repair got loose in the trans it would not be good, but I'm also not looking to spend the $70 on a new wire harness. I suppose a third option would be attempting to depin the OEM harness and replace and/or heat shrink the affected wires.

Test each wire in the harness with a continuity tester. It's possible that it's defective if the insulation is showing signs of wear.

No Improvement

I installed the updated separator plate ('98 P/N - compared and was exactly the same as 97 except for deleted hole 50) w/ bonded gaskets, as well as the epc blowoff valve. I repaired the wire sheath cracks with heat shrink (was able to remove harness and depin for that part of the job) and also tested continuity, which checked out. Got her all put back together with appropriate tourques and torque sequences. Also retorqued the bands - though they seemed fine, but this does eliminate a broken intermediate or OD band. Checked the reverse servo, seemed fine. As mentioned before I also checked the resistance on all solenoids, but this does not mean they are mechanically good.

All this work, and absolutely no change in symptoms - FML :roll: - at least I have a drain bolt now! The initial pressure test still indicates to me that this is a valve body issue though. Q: Is it possible for an internal problem to cause the lack of line pressure build - both mainline and epc - on WOT, as shown in the above pressure test results?

Q: Are there other diagnostic checks at my disposal for pinpointing a problem with the VB? If not, I was thinking of shipping it to Central VB's as BB suggested.

Fingers are still crossed that this is not an internal problem. The only other thing I can think to check w/o pulling trans is the intermediate and O/D servos, though I have read, and it sure looks to be the case, that this is a PITA with the trans in place. Any feedback appreciated.

Sonnax makes some items that address low EPC pressures check out their kit HERE. This kit requires the use of reamers and guides, this can make this kit expensive for a one time use, you may look into getting a reman valve body from someone like Central Valve Bodies or VBX Valve Bodies. I have used both before for many different applications.

I have thought about one of the fairly comprehensive rebuild kits from Sonnax, but given the cost of a reman'd VB at $260 vs some of the bigger kits at $100 (with no solenoids and the possibility of still missing the problem), I'm leaning towards a reman VB. The problem here is really one of diagnosis, i don't seem to have the VB knowledge and/or tools to determine the exact cause.

If there are any other diagnostic procedures for the VB that the home gamer can perform, I'm all ears. Otherwise it looks like the more expensive shotgun approach is in order, rather than die a death of a thousand cuts with various partial kit solutions.

Central VB's

I spoke with Central VB's today. They charge ~$125 just to test a VB, and ~$255 for a reman unit (w/ EF discount and CORE). The way he explained it to me was that if one bore was failing, the others were soon to follow. On the chance that it tested good, and say only the EPC was bad, you weren't saving much money w/ the testing fee + EPC at ~$75 from them ($200 total).

They do 5 updates to the reman units, including reaming and sleeving, check all solenoids - usually replacing EPC w/ new, this also includes their separator plate (he advised theirs was not bonded, that you could use the bonded but it would void their 1 year warranty) and gaskets, as well as replacing all o-rings.

All in all, a fair price. Compare to rockauto at $275 shipped - w/o any info on the reman process.

Looks I'll be riding shotgun...

No Improvement

I installed the reman VB from central... aaaaannndddd no improvement whatsoever. :roll: Still virtually no engagement in both R and D, but manual 1 and 2 function correctly. :thumbdwn::thumbdwn::thumbdwn:
When I look at the solenoid/clutch/band application chart, I don't see a link in the chain that would allow 1 and 2 to work, but not R and D. For instance, the reverse band should be good (and consequently the reverse servo and SSA) in order for manual 1 to engage.
The intermediate band (and consequently the intermediate servo and SSB) should be good in order to for manual 2 to engage.
Could it be that the coast clutch is jammed in the applied position? This would allow 1 and 2 to function, but possibly not any other gear except 4th.

My only other idea before pulling the trans is to attempt to pull the intermediate and/or OD servos, but I'm thinking this will be a wasted effort since these are only applied in 2nd, 3rd, and 5th - yet i cant even get 1st or R.


An air test plate would help you locate the section in the transmission with the issue. A small amount of compressed air is used to engage various sections of the transmission instead of hydraulic fluid with pressure.

Supplier for Air Test Plate

BB, do you have a recommended supplier for a test plate? All I could find is one on Bulk Part - $380 (A4ld - may not be compatible) and Rotunda Ford - $102 (5r55e but shows applications as '04-'06 - also may not be compatible).

Could not find on wittrans, transmissionpartsusa, transtar.

Though I have no experience with a test plate, and correct me if I'm wrong, it looks like you affix the test plate after removing the VB and observe components for function based on the circuit to which air pressure is applied.

This sounds like a helpful diagnostic procedure, and perhaps would either confirm or disprove an internal failure - although I would be surprised if my reman VB from Central is defective in the same way that my prior VB has failed. I suppose the possibility of a faulty PCM or shorted wire exists, though it doesn't feel like an electrical problem, and I did test the internal harness when it was out. So... most likely is an internal problem and the trans will have to come out.

If I can get test plate for a reasonable price, I would like to run that check, but I'm not interested in spending $400 for one. Still struggling to find much info on test plates online, knowledge on this seems to be thin and/or tough to find.

I did see ur post about the portable air supply mod. Unfortunately, I'm not seeing anything useful on eBay. Do you have a PN for the 5r55e test plate? That may produce more results.

Do you think this one will work? Listing shows its for a 5r55N. OTC tools site doesn't seem to list anything similar, at least that I can find. Judging from the shape of the VB on the N (with the solenoids being repositioned to a single corner) and looking at the shape if the test plate - vs the one linked below - i don't think the N test plate will work for the E.

There is also this one, but the price too high. Listing says "5r55", no letter designation, but it does also list the A4 - a closer cousin to the E.

Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!

This is starting to sound like a failed input sprag.

Would like to see the difference in the EPC pressure with the new valve body.