Solved 5R55E slow engagement when cold after a full rebuild.

[Brett]

I'm hoping that I can get some advice from the members here. I've been pounding my head against a wall for while now on this issue. I've searched nearly every thread, performed all troubleshooting steps according to ATSG and Sonnax manuals.

Here are some details:

1997 Ranger 4.0L w/ 5R55E transmission. I rebuilt a transmission core from a 1998 SOHC explorer. Trans worked fine prior to rebuild, and I went through it from front to back. New torque converter, bushings, frictions, gaskets, seals, o-rings, bands, filter, servos, epc, sonnax updates, rebuilt valve body etc. (This is not the first A4LD/4R55E/5R55E I've build. All the others I've done have worked flawless)

Transmission worked great for first 100-150 miles, then developed a couple odd issues.
1. Transmission will engage but not move when it is cold in reverse and forward all lever positions. It slips in any position forward or reverse - like if the transmission was low on fluid. After warming up for few minutes, the transmission does everything it's supposed to do normally and on test drives it goes through all the gears flawlessly at all speeds - No slipping and very tight.

2. New EPC went bad. Engagements were rough, trans shifted rough (after it was warmed up and would actually move). Tossed up a odd few codes relating to slipping between gears. After the EPC was replaced with another new part, these shifting issues went away. The EPC appeared to have a mechanical failure because it ohm'd out within spec, yet did not seem to actuate correctly when applying 12v to it. I'll call this issue is resolved.

Easy to see how the 2 problems above could be lumped together. Had to troubleshoot EPC issue first.

So the main issue I've been fighting is the low engagement when cold (like it is low on fluid - but it's not) and not moving in any gear position until warmed up.

These are the things I have done so far:
1. Replaced valve body with one from Central Valve Bodies. Same exact issue is there with the low engagement when cold. Shifts great once warmed up. This valve body is completely tested. Bolts all torqued to 88 in/lb.
2. Validated that separator plate was not mis-aligned.
3. Cleaned MAF, IAT and TPS. (suggestion from ATSG manual).
4. Adjusted both intermediate and OD bands.
5. When I built the trans, all of the drums were rebuilt and air tested for proper operation.

I decided to get a reman VB from CVB since sonnax suggests that this issue could be worn TCC and pressure regulator bores.

Could this be an electronic issue with PCM or other sensor?

I'm also going to try to replace the filter with another new filter in odd chance that the new filter is bad and blocking flow some how.

Anything else I can try at this moment before yanking this out and starting over?

Thanks
Brett

 

[BrooklynBay]

Check the O ring seals on the filter, and the low/reverse servo. Check the fluid level when it's cold (while it doesn't engage), then check the fluid level when it's hot (when it does engage). Take pressure readings when it's cold & hot, and compare these readings.

 

[Brett]

Thanks BrooklynBay.

Slight improvement with filter change, but still takes about 30 seconds - 1 minute for it to move when it is cold or if if has been sitting for a few hours. O-rings are all new. Fluid level is slightly above the hash marks cold or hot.

I need to get a new gauge. I will pick one up this week and check pressures.

In the meantime, I'll drive it for a bit to see if I can get any improvement with a few heat cycles.

Thanks
Brett

 

[BrooklynBay]

Did you use new valve body gaskets or a bonded separator plate (hopefully not both at the same time)?

 

[Brett]

No of course not.

Reman unit from CVB came with gaskets. Unit I build has a bonded plate. No change with delayed move between either of the VB's when cold or sitting for a few hours.

I'm leaning towards a possible converter issue or forward drum seal issue.

 

[BrooklynBay]

Remove the valve body, and connect an air test plate to test each section.

 

[JK080]

You describe a possible converter drain back issue.

Its not going to be with the forward drum if it does this in reverse, its going to be something common for all ranges, like the pump or converter.

If the converter drains then that would explain why you feel it engage and not move, the pump works because its driven by the hub, but the input shaft cant turn because the converter is full of air.

Confirm that the fluid is correct, then get it to engage and work like it should. Turn the engine off and check the fluid level on the stick after a minute or two, the level will be high on the stick so remember where its at or mark it.

Let it sit for the amount of time you have noticed that will cause the issue and check the fluid level again with the engine still off, it might be way up the stick from your mark.

This would indicate that the converter has drained.

This is usually a pump problem, like worn bushings or worn pump gears. I dont think I have delt with this on the 5R55E tranny, but thats not to say it cant happen.

 

[Brett]

Thanks JK.

I was thinking the same thing with the Torque Converter drain back issue.

I have taken readings on the dipstick. When warm the fluid level is about 1/16" above the cross hatches on the dip stick. When cold, it is about 3 1/2" above this.

I installed new bushings, seals, o-rings, and gaskets into the pump. I used the Ford tool to install the bushings so they are set to the correct depth. Pump gears did not appear to be worn and tolerances were in spec with my feeler gauge. Also, the core tranny I used to build came out of a running / driving truck.

Transtar did provide me with another TC under warranty. I am going to pull the transmission later today and get the other TC back to them. (They send them off to be tested for warranty). They were good about working with me.

 

[Brett]

Pulled transmission back out tonight. The Torque Converter was near bone dry inside. I didn't even drain it. Normally it should have a lot of fluid sitting in the bottom.

Note: even the core converters that I have sitting around, which have been drained, have more fluid sitting in the bottom of them.

I'll get it all back together later this week. Stay tuned.

Thanks
Brett

 

[joecrna]

Update us with your fix. I need to tear down another brand of vehicle trans to fix a similar issue and had not considered a TC issue. However, I do have reverse immediatly but must allow it to "warm up" about 30 seconds before any foreward gears will engage. Likely not TC for me but I am still interested.

 

[JK080]

I really don't think the converter is going to be your problem, the converter has no way to stop the fluid draining out of the hub. I feel like the problem will be in the pump. It would be worth it to take another look at the bushings in the pump, in particular the rear one. Make sure its the right one, the lube groove in the bushing should not go all the way from one side to the other, it should have a groove that looks like a "U".

Also check the o ring inside the inner pump gear, it could cause drain back issues if its missing or cut.

There is a valve and spring in the valve body called the converter relief valve, if its is stuck it cause this, but since you replaced the valve body its probably not it. Just something else to know about.

 

[BrooklynBay]

James, I have 2 questions about the later model pump gears with O rings. Is it possible to use these pump gears in an A4LD or is the torque converter not capable of fitting into the 5R55E's pump gears? Is there a benefit to having the O ring gears (the A4LD had gears without O rings)? I know that Sonnax makes valve body end plugs, boost valves, and other parts with O rings to provide a better seal. Another company makes servos with O rings to be used on the 5R55W with servo bore wear.

 

[Brett]

Not seeing how the pump gear o-ring would prevent a drain-back issue since it goes around the outside of the hub assembly on the converter.

Once I pull the bellhousing and pump out, i will recheck the bushings on the pump.

Thanks
brett

 

[JK080]

I am not sure on interchangeability with the pumps, I have never done that with these. I do know that the converters for the A4LD and the 5R55E -S/W/N use the same bellhousing bushing and the hubs on the converters are the same. So I would think it would be possible to use the gears with the o rings in the A4LD without any issue, again I haven't done this.

I just measured a new set of A4LD and 5R55E gears and they are the same thickness at 0.510.

As far as I know they added the o ring to help improve lock up and help keep the prime of the converter. Thats what I have been told... I will see if I can find any literature about it.

 

[Brett]

I believe the o-ring in the pump gears is to improve the lube to the front pump seal and converter bushing instead of letting fluid pass through the pump gears.

 

[BrooklynBay]

I wonder if the improved O ring gears helped eliminate the front seal blow out issue that the A4LD had. I don't recall reading about this issue in the later 5R55E/W/S/N versions. Maybe these gears could be added to the A4LD along with replacing the bushing, and drilling a larger drain back hole in the bellhousing?

 

[JK080]

Yes I believe you guys are right, I found this - LINK

It states that the o ring was added to help prevent front seal blow out.

 

[BrooklynBay]

This is good to know! A lot of people have complained that they were still having seal blow out issues even after replacing the seal, bushing, bellhousing, etc. Now that we're onto something, here's a post from the Project Frankentranny thread about using these gears: http://www.explorerforum.com/forums/showpost.php?p=1330103&postcount=3

 

[Demo1986]

Sub'd

 

[BrooklynBay]

Thanks for posting the link. It looks like the article might have been in one of the older Gears Magazine issues. It was written before Ford came out with the 6 speed transmission, so now we know where Ford got the idea from.