4L60E Information Thread

[PM18S4]

I got that one as well as an OEM pan that was tapped with a drain bolt to compare....


I will follow up with another post on the modified OEM pan with a drain installed.

The OEM with a drain hole added.

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1. Definitely used pan given that ding in the conner, thankfully it's steel and just deformed instead of cracking.
2. Plug bolt is recessed below the bottom surface.
3. Not sure on the quality of the seal on installed plug, but the plug bolt has a washer that should cover the entire interface.
4. The inside of the drain sticks up quite a lot, not sure if it will interfere with the insides of the transmission, doubt it given it's a 'deep' pan.

 

[littletunny]

Hello everyone! New here!

Has anyone ever dealt with low line pressure in a 4l60e?

I just recently rebuilt a 2007 4l60e off of a Sierra. Ran great for 3,000 miles then the 3-4 clutches fried.

I connected a pressure gauge to the transmission and it wont go above 60 psi in any gears except reverse where it will pop to 100 psi. This is below spec - you should be able to blip the throttle and see the pressure jump. Mine stays flat or barely moves.

I unplugged the transmission harness which disables all electrical and should provide MAX line pressure but there was no change in the operation which leads me to believe its mechanical ie bad pump??

Maybe the boost valve is missing the internal spring?

Any other tips to look for before i drop the tranny again? Thanks!

 

[NickTransmissions]

Hello everyone! New here!

Has anyone ever dealt with low line pressure in a 4l60e?

I just recently rebuilt a 2007 4l60e off of a Sierra. Ran great for 3,000 miles then the 3-4 clutches fried.

I connected a pressure gauge to the transmission and it wont go above 60 psi in any gears except reverse where it will pop to 100 psi. This is below spec - you should be able to blip the throttle and see the pressure jump. Mine stays flat or barely moves.

I unplugged the transmission harness which disables all electrical and should provide MAX line pressure but there was no change in the operation which leads me to believe its mechanical ie bad pump??

Maybe the boost valve is missing the internal spring?

Any other tips to look for before i drop the tranny again? Thanks!

You'll need to test the EPC, valve body and pump. Check out this video for "how-to" test and diagnose low line pressure conditions in those transmissions.

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I also suspect a combination of boost valve and pressure regulator valve along with possible AFL valve wear.

 

[NickTransmissions]

The OEM with

1. Definitely used pan given that ding in the conner, thankfully it's steel and just deformed instead of cracking.
2. Plug bolt is recessed below the bottom surface.
3. Not sure on the quality of the seal on installed plug, but the plug bolt has a washer that should cover the entire interface.
4. The inside of the drain sticks up quite a lot, not sure if it will interfere with the insides of the transmission, doubt it given it's a 'deep' pan.

That pan should be good to go. I use a similar, modified pan that is sold on ebay for $40 shipped or so. Not sure if the bolt is oem or not (dont think it is) but neber had any negative feedback about them.

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[Scooterwrench]

I got that one as well as an OEM pan that was tapped with a drain bolt to compare.

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Both appear to have the same depth and bolt pattern and interface, but the aftermarket one has some serious flaws.

Check the pan rails for straightness. I bought a TCI very similar to this with warped pan rails. A little work with mill file and straightedge made it all better.

1. Die cast aluminum body + plug bolt without a magnet embedded into it = no way to catch fines.
2. Plug bolt extends well beyond fins, just waiting to get caught by a stray rock.

You may be able to find a button head bolt that doesn't stand so tall. Epoxy the flat magnet out of your old pan to catch ferrous debris.

3. The casting has some really sharp flashing around the ejector pin punches and the "Made it Taiwan" Stamp.
4. I have some serious questions regarding the ability of it sealing properly.

I will follow up with another post on the modified OEM pan with a drain installed.

 

[littletunny]

If I am rebuilding a 4l60e to stock can I still drill the separator plate? I see where some people drill the 3-4 feed hole I assuming to keep fluid pressures up.

 

[NickTransmissions]

If I am rebuilding a 4l60e to stock can I still drill the separator plate? I see where some people drill the 3-4 feed hole I assuming to keep fluid pressures up.

Yes. Drill the 2-3 feed, band release and 3-4 feed to .093 if you have a stock stall TC. You can enlarge the 1-2 feed but dont go more than .075 with a vette servo and factory stall, otherwise part throttle shifting may be a bit harsh.

 

[gkrodgers]

hi i was wondering if any body could help me i have a 91 gmc c1500 with a 96 350 and a 4l60 so far we have been able to drive it a few hundred yards tried to park it. it wouldn’t go into park then decided to go back to the shop. got to a stop sign and he wouldn’t go while in gear would rev to his max but wouldn’t move so we pulled him back to the shop turned him off checked the trans fluid it’s good and let him cool then turned him back on put him in reverse and he decided to move. does anyone have an idea what could be going on or do i just need to suck it up and spend the money to get a new transmission

 

[Erik the Awful]

Check the transmission fluid level. Also look at and smell the fluid to make sure it isn't burnt or full of dead friction material.

 

[NickTransmissions]

hi i was wondering if any body could help me i have a 91 gmc c1500 with a 96 350 and a 4l60 so far we have been able to drive it a few hundred yards tried to park it. it wouldn’t go into park then decided to go back to the shop. got to a stop sign and he wouldn’t go while in gear would rev to his max but wouldn’t move so we pulled him back to the shop turned him off checked the trans fluid it’s good and let him cool then turned him back on put him in reverse and he decided to move. does anyone have an idea what could be going on or do i just need to suck it up and spend the money to get a new transmission

Sounds like multiple clutch packs are burnt, your symptoms (only going by what you wrote) tell me that transmission needs to come out for overhaul.

Also, when you're using the word 'he', are you referring to the truck, transmission or the driver (assuming you were not the driver on that particular test drive)?