No pressure rise

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Bluechevy18

Newbie
Joined
Jun 27, 2022
Messages
13
Reaction score
10
Location
Alabama
97 c1500 Rebuilt 4l60e- old trans blew the front planetary bearing. Needle bearing destroyed gear. Rebuilt it, had the pressure gauge on it for the first 300+ miles. Seen everything was good to go soi took it off- now I’m at 650 miles and noticed 2-3 shift was flaring/slight slip shifting above 3.5k rpm. Put pressure gauge back on and it has great base pressure 70/130 .. but it will not rise no matter what i do.. turn EPC up/down , changed boost valve back to stock, even unplugging the harness doesn’t make it default to high pressure.. truck runs great shifts smooth under normal driving. But u can start to smell the burnt fluid.. everything was replaced or rebuilt besides the case itself. I checked valve body for stuck/sticking valves . There all free and smooth. All solenoids work .. TPS/MAF/MAP all in spec. One other thing- when it started flaring i dropped the pan and the EPC solenoids wires were pinched between case and pan and it blew the fuse.. i replaced solenoids and wire harness didn’t change.. any ideas where to start looking ? Thanks ,Brad
 

stutaeng

I'm Awesome
Joined
Aug 7, 2019
Messages
3,410
Reaction score
4,348
Location
Dallas, TX
What do you mean "has great base pressure at 70/130 psi...but it will not rise no matter what I do"? Is that pressure at idle and under high throttle flip? Are you saying the pressure does not increase with increase in RPM when you are driving it?

Since you mentioned disconnecting the harness doesn't make the default maximum line pressure, I would think there's a hydraulic leak somewhere in the hydraulic circuits...but it's perplexing that it had good pressure in the beginning... If there is not enough fluid pressure to engage a clutchpack, it will burn up for sure. Probably should stop driving it.

There's a specification for checking pump body flatness with a feeler guage. The pump body didn't have any steps? Did the slide pin have any wear?Did you check the front drivetrain with compressed air before reassembly? I believe there are several feed holes on the input shaft you can check to see if you have leakage. What do think caused the initial failure? Maybe lack of lubrication? Maybe the initial issue was not resolved? I'm just thinking out loud here.

About your EPC: you should check for voltage/amps. The ATSG has information on page 9.


Sorry, I'm not too familiar with the 4L60e.
 

Bluechevy18

Newbie
Joined
Jun 27, 2022
Messages
13
Reaction score
10
Location
Alabama
What do you mean "has great base pressure at 70/130 psi...but it will not rise no matter what I do"? Is that pressure at idle and under high throttle flip? Are you saying the pressure does not increase with increase in RPM when you are driving it?

Since you mentioned disconnecting the harness doesn't make the default maximum line pressure, I would think there's a hydraulic leak somewhere in the hydraulic circuits...but it's perplexing that it had good pressure in the beginning... If there is not enough fluid pressure to engage a clutchpack, it will burn up for sure. Probably should stop driving it.

There's a specification for checking pump body flatness with a feeler guage. The pump body didn't have any steps? Did the slide pin have any wear?Did you check the front drivetrain with compressed air before reassembly? I believe there are several feed holes on the input shaft you can check to see if you have leakage. What do think caused the initial failure? Maybe lack of lubrication? Maybe the initial issue was not resolved? I'm just thinking out loud here.

About your EPC: you should check for voltage/amps. The ATSG has information on page 9.


Sorry, I'm not too familiar with the 4L60e.
What do you mean "has great base pressure at 70/130 psi...but it will not rise no matter what I do"? Is that pressure at idle and under high throttle flip? Are you saying the pressure does not increase with increase in RPM when you are driving it?

Since you mentioned disconnecting the harness doesn't make the default maximum line pressure, I would think there's a hydraulic leak somewhere in the hydraulic circuits...but it's perplexing that it had good pressure in the beginning... If there is not enough fluid pressure to engage a clutchpack, it will burn up for sure. Probably should stop driving it.

There's a specification for checking pump body flatness with a feeler guage. The pump body didn't have any steps? Did the slide pin have any wear?Did you check the front drivetrain with compressed air before reassembly? I believe there are several feed holes on the input shaft you can check to see if you have leakage. What do think caused the initial failure? Maybe lack of lubrication? Maybe the initial issue was not resolved? I'm just thinking out loud here.

About your EPC: you should check for voltage/amps. The ATSG has information on page 9.


Sorry, I'm not too familiar with the 4L60e.
Thanks for getting back to me. When idling, pnd321 all read 70psi/ reverse goes to 130psi.. change in rpm- driving- changing EPC amps. doesn’t increase pressure at all, but maybe 2-3psi.. i used the scanner to change the amps on EPC from 1.05 to 0.1 and still nothing.. test driving/ reving i can see the EPC working as it should. All solenoids are working as they should. The pump is the original , just rebuilt with new vanes-slides-springs-and so forth.. i don’t kno why the trans destroyed the bearing originally , i assumed it was just it’s time to fail. It Was original trans with 200k miles on it.. Before i rebuilt it i only had 1st 2nd and reverse since the planetary gears where destroyed and And wouldn’t budge.. but the pressure would increase, it was just on the lower side of the (in spec) range .. i did forget to mention it is the original valve body .. It was just taken apart and cleaned ,with just a couple new parts and the transgo correction kit … i DON’T have a vacuum tester for the valve body …. I guess now I’m trying to understand the pressure part of the trans. From what I understand, it suck’s fluid up in the filter / spins it through the vanes out the PR/ boost valve and from there it’s a direct link to the pressure test port? Considering they share the same fluid port ( i think)… IF that’s correct then it should be directly related to the pump not the valve body?? And the fact that it didn’t default to max pressure unplugged Makes me lean towards a pump problem?… and the input drum was air checked prior with no signs of leakage and teflon rings where resize correctly.. I’m not a pro by any means so plz correct me if any of that is wrong.. Im assuming I’ll have to replace the clutches since i kno some of the material has had to burnt off , which is fine, im just trying to find out if it’s valve body or pump problem. Or even buying a new input drum if need be.. but i just didn’t want to throw parts at it.. since it’s getting line pressure, doesn’t that mean the pump is working? And since unplugging the harness didn’t help and evening else is working that means the ECM is not fried?.. srry for long post. Having to reply when i get free time at work so trying to get it all out
 

stutaeng

I'm Awesome
Joined
Aug 7, 2019
Messages
3,410
Reaction score
4,348
Location
Dallas, TX
Um, Transgo shift kit you say? I was told by a member here a few months ago his Transgo shift kit had a missing opening on the separator plate:

If the force motors IS working correctly, then something is wrong with either valve body and/or pump. If you have a massive hydraulic leak, you will obviously never build pressure, even if the pump is pumping fluid. I'm not sure what else you could do at this point. Do you still have the original separator plate? The master overhaul kit usually has the valve body gaskets. Do you still have yours? Maybe go back to that and see what happens?

...from another thread (it was regarding a 4L80e that I rebuilt) posted by @tayto
"jakes kit is nice but not sure you want to be deleting accumulators without tuning FWIW. heads up on the HD2 kit, I recently did one in a 92 GMC. the plate was manufactured incorrectly and causes me a bunch of grief. had the valve body out 3 times pulling my hair out until I found the problem. they had used 2 top plates and 1 bottom plate. the middle plate was missing a slot

Edit: you can "air check" these holes and make sure air flows from 1 to the other.

Attachments​

  • You must be registered for see images attach

    IMG_20210815_112529_5.jpg
    126 KB · Views: 6
  • You must be registered for see images attach

    signal-2021-08-15-120832.jpg
    248 KB · Views: 6"
 
Last edited:

Bluechevy18

Newbie
Joined
Jun 27, 2022
Messages
13
Reaction score
10
Location
Alabama
Unfortunately i don’t have the old one.. the check ball punched right through it and i knew i wouldn’t need it… the build was done almost 2 years ago.. its not driven much at all as u can tell.. I’ll check the plate vs gasket holes and see if they all line up and go from there… would anyone happen to know if i was correct with the steps/ process of how the pressure is boosted from the filter to the pressure port? If the epc is suppose to Increase the pressure how does it read on the gauge if it’s supposedly goes to the gauge before the force motor? IF i decide not to rebuild again with more new parts, where does someone get a new trans that’s actually done right? I’ve never owned a Monster trans but i haven’t read any good things about them.. i need a stock, 400hp capable, no hassle trans.. im guessing with what I’ve already spent on first build plus what I’ll spend on the new parts and another kit i can prolly spend couple more bucks and get one that should have a 100k mile warranty.. considering it will never see that many miles while I’m still alive anyway
 

HotrodZ06

GMT400 Collector
Supporting Member
Joined
Apr 30, 2016
Messages
172
Reaction score
217
Location
Lake Texoma
I've had a couple that no matter what we did it would flare in the 2-3 shift. One we fixed with a mass air sensor, the other the last resort was tuning the transmission side of the pcm. I went in and upped the pressure modifiers and shortened the shift times and so far seems to be holding together.
 

Caman96

OEM Baby!
Supporting Member
Joined
Jul 17, 2020
Messages
6,641
Reaction score
12,839
Location
The Hub

Caman96

OEM Baby!
Supporting Member
Joined
Jul 17, 2020
Messages
6,641
Reaction score
12,839
Location
The Hub
That's interesting will have to remember that, but the ones with the flare were gmt800s but had 4L60E's so thought it might be relevant being the same transmission.
You must be registered for see images attach
 
Top