5r55e rebuilt but having problems going into drive

[EricB123]

So I've put about 15k miles on this transmission that I rebuilt. It worked pretty well most of the time. I do have to back off the accelerator in the 2-3 transition for it to shift. I took it to a mechanic who test drove it and thought the problem was related to the valve body. I didn't rebuild the valve body other than change all the solenoids and wire harness, and gaskets. Someone had previously installed the shift kit, but everything looked ok.

Around 15k miles after a long heavy tow and drive -- nothing too heavy, just the first time up and down the mountain. All was good until I got to a light and when I went to accelerate it didn't want to engage, and then there was a shutter and it started to go.

Slowly it's been getting worse and sometimes shuttering in 3rd while driving. So I replaced the valve body and found the oil was dirtier than I expected. Unfortunately it seems to still have problems engaging.

Any thoughts on what this problem(s) would be?

Thanks for the help. This forum helped me last time during the rebuild a lot. I hope this one isn't too serious.

 

[transman304]

What problems did you find on the transmission when you tore in down originally? What parts were replaced?

 

[974X4BLACKSPORT]

First and foremost above all, check the hyd. pressure from service ports on transmission case. This will help you pinpoint the problem.

 

[EricB123]

Originally the transmission was burnt out and heavily abused. I replaced many hard parts, sensors, gears, center support, bands, plates, etc. along with all of the soft parts. I couldn't find anyone to service the torque converter so I flushed it multiple times but I didn't replace it.

I do have another update. After letting it sit overnight and running it this morning, I found it was still at least a quart low on fluid. After that the shifting was normal with a little 2-3 flare but the previous problem of having to back off the accelerator was gone.

However it is still slow to go from neutral to drive and will still shudder occasionally. I'm letting it sit some more for the oil to settle out of the tube so I can remeasure the level. I don't know why but I seem to really struggle getting good transmission oil level readings.

I'm not familiar with how to check the hydrostatic pressure or exactly where the service ports are. Can you point me to some information on how to do that and what the test limits should be?

Thanks again for all the help. This is my first AT rebuild so it's all new to me.

 

[transman304]

Like @974X4BLACKSPORT said you definitely need to get a pressure reading before proceeding. Unfortunately you can’t flush lock up converters and get them clean enough to reuse. If you had that much damage to require hard parts and not replacing the converter, did you flush the cooler lines and cooler? You have contaminated the build with debris from previous failure and will more than likely need to be gone over again. Get a pressure reading and post it as it may be something that doesn’t require a overhaul. Good luck.
Brad

 

[EricB123]

Thanks for all those details Brad. I was extremely careful. I pressure flushed all the lines (in fact I installed 4 new lines as the old ones were corroding) and cooler about 3 times and I installed an additional magnetic filter in line on the return going to the transmission. I looked at replacing the cooler but it was pretty expensive and mine was in visibly good shape and flushed clean after the first flush. The torque converter was the only item I didn't feel 100% sure on but I fully flushed and drained it 3 times (mineral spirits followed by AT fluid over the course of many days).

Looks like I'll have to order that gauge. Does this look about right: https://www.amazon.com/ABN-Engine-Pressure-Transmission-Diagnostic/dp/B0778XD4JT/

Is it measured by just putting it in R or D at idle? Where is the EPC pressure measured?

 

[transman304]

You can get the pressure gauge set up at advance or auto zone to use and return.(at least my local stores do this) Get a line pressure reading and see where they end up and then you can test the EPC. Different steps for that test. The only way to get the converter clean is to cut it disassemble it replace friction material and any other worn parts and weld it back up. A reman converter will cost in the 100-150 dollar range.

 

[EricB123]

Unfortunately there is nowhere to get loaner tools other than Oreilly and they don't carry it. Is there a fitting for the EPC I should look for too?

Something interesting I noticed that seems to be very consistent is that if I switch from N to D it takes several seconds to engage and engages with a pop but if I go past to 2 or 1 it shifts immediately and fairly smoothly. I'm not sure what that might mean. Shifting while driving seems to be fine. I have not done enough testing with the new valve body in hot conditions and starting and stopping to notice anything specific. Sometimes it's fine and other times it seems to slip and shudder but poping it into 2 or 1 seems to fix it -- but I haven't tested the case of stopping in D and then taking off again very much.

Edit: I talked to a shop about that process for the torque converter but they wouldn't do it because they were concerned about getting it balanced properly after welding again. I couldn't find a new one shipped to here for anything less than about $275 and I got a lot of mixed input on the necessity of replacing it at the time. So I did my best to get it clean.

I was just reading this article and I'm starting to think maybe the TC is what is failing: Torque Converter Problems: Signs, Causes, & Replacement

Would the pressure gauges show this as rapid rises and falls in pressure? Or is there something else to look for?

It's my only vehicle right now so we're in a tight spot to sort this out. Thanks.

 

[EricB123]

I've ordered a rebuilt TC. Since shipping takes so long I have to try and anticipate other issues. Should I consider getting another full rebuild kit or pump? There was a lot of fine friction dust and some metal dust, but it was all very fine. Any insight from experience would be appreciated.

 

[transman304]

Same gauge and fitting to test EPC but needs to be driven while monitoring pressure rise and fall. Not a fan of the inline filters as they will stop flow after getting filled with debris. What did the top of the valve body look like after you removed it to replace with the other one? Debris, friction material, brass shaving? Seems as though you have several issues that may or may not be related and if you are still driving the vehicle you definitely are continually damaging it. I seem to think you did a proper overhaul with getting 15k out of it but shot your self in the foot by not using a rebuilt converter. As far as what you are going to need will be determined when you go back through it. Being under a time crunch with only one vehicle will make the job harder to be successful. Things will get overlooked or clearances will not be set and you end up wasting more money. Get the pressure readings ASAP. On a side note: are you getting any trouble codes?

 

[EricB123]

(I'm not getting any trouble codes on the transmission)

It took forever to get the test gauge shipped here. But I was able to test them today.

Idle - 79 psi
Drive - sits at about 80, then jumps to about 145 psi but no higher, then there is eventually the feeling of it engaging.
Reverse - sits at about 150 then jumps to around 200 psi and engages quickly

It seems like it's inside the spec. range but reverse and drive behave differently and reverse has no shifting problems or delays.

Any thoughts? Thanks!

 

[transman304]

Try the WOT(wide open throttle) test and see what readings you get. Follow the instructions as you will heat up the converter very quick. Let us know what you find. Another thing you could try is to unplug the electrical connector and start it and see if engages faster. It will put it in failsafe and set max line pressure. If it seems to engage normally may need to check EPC function.

 

[EricB123]

Thanks again for all your help on this.

I didn't do reverse WOT but here's what I'm seeing. I don't really know what I'm looking for as the gauge sometimes jumps around. After repeating the test a couple times it stopped jumping as much (gauge equalizing? I don't know but I found afterwards there was some signs of leakage on the test setup - maybe at high pressure).

Gear - Idle / WOT (waited for engagement to happen first)
P - 80 /
R - 120 (jumps to 185) /
D - 100 / 233
2 - 100 / 230
1 - 85 / 235

With the plug pulled (I didn't have the gauge connected during this test) with the Starting Gear -> Next Gear noted:

P -> R or N -> R Engages and moves fine
N -> D No engagement
D -> 2 or N -> 2 Engages fine and moves (note that when problems started when I can't get it to engage, I often get it to move by dropping to 2 or 1 then back to D)
D -> 1 or N -> 1 same as above D -> 2 or N -> 2
2 -> D or 1 -> D Slips a little but engages a little roughly and then drives

 

[974X4BLACKSPORT]

If the gauge is jumping around alot (it should not), you could be sucking air instead of fluid. I would find out why and fix it, gauge should be steady through all pressure ranges.

 

[EricB123]

I'll try retesting and see if I can get it more stable. I watched a youtube video and saw how the gauge worked for them.

Any thoughts on why without the electrical plug I get:

N -> D No engagement
but
1 -> D and 2 -> D it engages?

Is it worthwhile to monitor the pressure during this test too?

 

[transman304]

Did you replace the OD sprag when it was apart? Or check to make sure it was holding in the correct direction?

 

[974X4BLACKSPORT]

I'll try retesting and see if I can get it more stable. I watched a youtube video and saw how the gauge worked for them.

Any thoughts on why without the electrical plug I get:

N -> D No engagement
but
1 -> D and 2 -> D it engages?

Is it worthwhile to monitor the pressure during this test too?

When you have the gauge installed and checking the pressure, if the gauge needle is jumping all around (not steady), that indicates a problem. You should not have more than a couple PSI deviation in the needle indication when the transmission is in operation. A bouncing needle on the gauge can mean many things, one possibility is you could be sucking air on the inlet side of the pump instead of fluid, this will cause the needle to jump around when in operation and testing.

 

[EricB123]

It definitely moves around a lot. I took a video of going from start and walking through the gears (you can see the shift indication in the background and hear it). Every time I check the fluid level I get different results. I'll let it sit overnight, check it, start it and walk it though the gears then take an oil level measurement. It's never close to the same and it is driving me crazy.

Here's the short video from a cold start at idle conditions:



I do have a slight leak that just drips a little when the gauge is connected but it is pretty small drip. Other than that, I think the test is setup right.

 

[EricB123]

Did you replace the OD sprag when it was apart? Or check to make sure it was holding in the correct direction?

It's been a while and I replaced a lot of stuff. I'm pretty sure I replaced the sprag and I was careful with the direction, but it's not impossible I did something wrong there.

Is this your concern (14min into this tear down):

 

[EricB123]

I don't have any more ideas where to go from here and I need to get this vehicle fixed. The pressure is as shown in the video above and I'm not sure why it bounces so much. Without any further suggestions here's my plan;

• Remove transmission & inspect
• Replace torque converter
• Replace sprag (having a hard time finding OD part with a new race)
• Flush lines and cooler
• Install new filters
• Reinstall transmission and test again

Assuming I don't find any other problems do you think this will cover my bases or should I find a planetary gear with a new race for the sprag as well?

Thanks