Slipping trans after rebuild.

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NickTransmissions

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I flushed the cooler with some cooler flush. And put the same stuff in the converter. I took some advice on drilling a hole and putting in a drain plug for it. So ran a few qts through after til it looked good. Dk if it was a good idea or not. Just was told they had done that multiple times.
What do you mean you put the same stuff in the converter? The converter should have been brand new...
 

BradHanks15

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Yank it. Reman the pump; never rebuild a trans without going through the pump and valve body. Machine both pump working surfaces, install new rotor guide and vanes along with a sonnax boost valve kit (4L60E-LB1). Overhaul the valve body; convert the PWM to an on-off using whichever method you prefer.

Pressure test the forward drum - make sure it's not leaking at the base welds.

If you havent, replace the harness, psma, solenoids and vss.



He would have destroyed the pump immediately upon start up; no movement period.
Thanks. I did take the two halves of the pump apart and everything looked great inside of it. No grooves and the rotor moved just fine afterwards. I definitely did not replace the boost valve though. Do you think that’s part of it? How do you pressure test the forward drum? What is the Psma? Thanks.
 

NickTransmissions

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Thanks. I did take the two halves of the pump apart and everything looked great inside of it. No grooves and the rotor moved just fine afterwards. I definitely did not replace the boost valve though. Do you think that’s part of it? How do you pressure test the forward drum? What is the Psma? Thanks.
My guess is clearances between the pump body deck and top of the rotor and slide are way more than the .0015-.002 servicable clearance limits...Here's my 4L60E playlist where I have all sorts of videos on that trans...You can check out my 4L60E tear down and inspection video for info on forward drum pressure testing (i also think i have a short vid just showing the pressure test process). That tear down video covers all other points of inspection.

PSMA= pressure switch manifold assembly.

So you are neutral in 3rd gear (meaning it does shift from 2nd to 3rd but feels like neutral after shifting) or it doesn't upshift at all, just stays in 2nd gear?
 

BradHanks15

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My guess is clearances between the pump body deck and top of the rotor and slide are way more than the .0015-.002 servicable clearance limits...Here's my 4L60E playlist where I have all sorts of videos on that trans...You can check out my 4L60E tear down and inspection video for info on forward drum pressure testing (i also think i have a short vid just showing the pressure test process). That tear down video covers all other points of inspection.

PSMA= pressure switch manifold assembly.

So you are neutral in 3rd gear (meaning it does shift from 2nd to 3rd but feels like neutral after shifting) or it doesn't upshift at all, just stays in 2nd gear?
Thanks for the explanation. There’s no upshift. Won’t do anything except in D.
 

BradHanks15

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Thanks for the explanation. There’s no upshift. Won’t do anything except in
Thanks for the explanation. There’s no upshift. Won’t do anything except in D
My guess is clearances between the pump body deck and top of the rotor and slide are way more than the .0015-.002 servicable clearance limits...Here's my 4L60E playlist where I have all sorts of videos on that trans...You can check out my 4L60E tear down and inspection video for info on forward drum pressure testing (i also think i have a short vid just showing the pressure test process). That tear down video covers all other points of inspection.

PSMA= pressure switch manifold assembly.

So you are neutral in 3rd gear (meaning it does shift from 2nd to 3rd but feels like neutral after shifting) or it doesn't upshift at all, just stays in 2nd gear?
makes sense on clearances.
 

NickTransmissions

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Thanks for the explanation. There’s no upshift. Won’t do anything except in D.
No upshifting at all? In other words, you're staying in first gear?

If so, check the VSS - make sure it's plugged in. If it is, make sure it's working or simply replace it with an AC Delco VSS. If there's still no upshift from first with new speed sensor then you'll need to determine the source of the problem (vehicle's harness from the PCM to VSS or PCM itself, etc).
 

BradHanks15

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My guess is clearances between the pump body deck and top of the rotor and slide are way more than the .0015-.002 servicable clearance limits...Here's my 4L60E playlist where I have all sorts of videos on that trans...You can check out my 4L60E tear down and inspection video for info on forward drum pressure testing (i also think i have a short vid just showing the pressure test process). That tear down video covers all other points of inspection.

PSMA= pressure switch manifold assembly.

So you are neutral in 3rd gear (meaning it does shift from 2nd to 3rd but feels like neutral after shifting) or it doesn't upshift at all, just stays in 2nd gear I
The problem with both converters and coolers is that they have so many tiny passages in them it’s almost impossible to flush them clean. The tiny metal and clutch materials get in every nook and cranny.
Yeah makes sense.
 

BradHanks15

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No upshifting at all? In other words, you're staying in first gear?

If so, check the VSS - make sure it's plugged in. If it is, make sure it's working or simply replace it with an AC Delco VSS. If there's still no upshift from first with new speed sensor then you'll need to determine the source of the problem (vehicle's harness from the PCM to VSS or PCM itself, etc).
I did replace the vss. I don’t think it would upshift. It won’t go past 15 mph. It only takes a certain amount of throttle input then just completely let’s go. Not enough speed to warrant an upshift.
 

NickTransmissions

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I did replace the vss. I don’t think it would upshift. It won’t go past 15 mph. It only takes a certain amount of throttle input then just completely let’s go. Not enough speed to warrant an upshift.
You should be shifting into 2nd at or before 15mph. Put a bi-directional scan tool on it to see if a shift is being commanded or not. That will at least tell you what the PCM is telling the transmission to do. If it's not shifting, command a shift to see how it reacts.

Another test is to see if it moves forward without a link to the PCM - unplug the large, round case connector from the trans, fire it up and see if it will move on it's own. You'll be in third gear (limp mode) when you do this so dont try to drive it around on the street. You're just looking to isolate the trans from the PCM to see if your 3-4 pack, forward clutch are both working.
 
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