4L60 seems to slip at high speeds and no reverse forward at start up

ivane21

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#1
Please fill out the following to ask a question.

MAKE:Chevrolet
MODEL: Tahoe 2 dr
YEAR: 1998
MILES: 165000
ENGINE: 5.7L
DESCRIBE ISSUE....my transmission went completely out about 4 years ago. I couldn't find a rebuilt one to install myself for less than $1200. I finally found one in San Diego, I scheduled a trip for work and pulled a trailer out with my old trans. When I got there they had one all pretty and painted for a 2wd so they had to change the bellhousing from my core which they said would entail taking it most apart again. The trans doctor guy did it overnight and it was ready for me the next morning. I installed it and got 3 good winters out of it. It's sits alot in summer and I only drive and keep it for nostalgic reasons last year of two door.

But last time I drove it it was making a funny noise on the highway like it was slipping in overdrive. When I go to move it once in a while I jump in start it and put in reverse and nothing. Same with drive. If I put it back into park and wait it will work fine. If I dont put it back into park it will go very very slow unless it's actually just rolling down the driveway, hard to tell...

I checked the fluid and it's clean and smells good.
This transmission has a maximum of maybe 10,000 on it. Maybe less. I drove it less than 6 times last winter.

Is there any valve or servo or adjustments that I can make?

I'm open to anything.

I love this truck, and winter is not far away.

I won't spend $1200 for another rebuilt and I won't remove and install myself in the driveway ever again...

Hoping for some good advice or suggestions from you guys.

PS. I have rebuild older Chrysler FWD transmissions and tinkered a little with insides of older ford and GM RWD also so I've got some experience here. Just hat the R&R work without a lift.

Thanks in advance
 
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#2
did you scan for codes?
I always ask are you SURE it is slipping or is the TCC on and off - same sensation and tach indicators...

Not driving and long periods of non use can also cause issues - seals drying , lack of 'prime' in pump. fluid pickup line, drainback etc...
Check codes, pay attention to slipping or TCC issue, and drive it more this week - add 1 bottle lubeguard red..... less than 10$ and a plan
remember I am an optimist -
 

bp042665

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#3
Kev is right the problem with it not moving at first is the converter has drained and needs to refill but i tell everyone here in south carolina that let them sit to start it 1 a month and let the fluids all warm up to keep the seals soft
 

billr

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#4
This is actually a 4L60E, correct? Yeah, I would be quite surprised if there are no codes. Use live-data, too. That will show you things like TC slip as a simple number, no guessing what is going on there.

I have a 4L60E that started showing P1870 for "TCC Slip" about 8 years and 75K miles ago... still working fine; but I will be following this thread closely!
 

billr

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#6
There is certainly a lot of detailed info there, I sure hope I (and the OP) never have to understand it all!
 

ivane21

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#7
Sorry for the silly question here?
But will the trans codes come from the same obd2 connector?

I remeber 4wd codes being different on this one.

I added some the the red lube suggested and will be driving all week and monitoring.
 

nickb2

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#10
@Kev, I for one, will certainly take the time to read that really nice chunk of PDF. I lack poorly in the trans department. This will help me better understand these "E" tranny's. Thx.
 

ivane21

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#12
Ok I scanned codes afyer driving for a bit. I have about 10 codes.
One is P0300 random missfire...
Not sure about that since it runs very well. The other 9 codes all all O2 sensor related as I have a leak at the flange on the manifold on the passenger side. I have a new flange and gasket but not good at welding. I'm hoping to simply install it and find a clamp of some sort to work. Problem is that the o2 sensor is so close that I'm not sure I can do it myself. I'm going to try.
But mostly Heated o2 codes and o2 out of range and such. Some lean/rich codes too which seem normal and possibly could created the random misfire....

Now for the trans. I got a code P01870. I looked at the nice PDF that was sent over and don't see that code. I did google it and watched a couple of videos about a TCC valve that gets hung up and installing a new valve and spring that will get rid of the code. Not sure on that. Sounded like he said it was in the pump...I'd hate to pull that... valve body not too worried about pulling. Just need a case of fluid and filter and to know where all those little balls/BBs go back as I think some fall out when removing them...

Any input or ideas would be appreciated, I haven't driven too much maybe I can hit the valve unstuck by driving it with that fluid I added.

I want to sell the truck but I cant/won't do that until I fix all that I can. Thanks guys!
 

billr

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#13
BP, can the OP easily remove the trans-temp sensor and "Tee-in" a pressure gauge to see what line-pressure is doing when it won't go into F or R?
 

nickb2

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#14
Bill, I don't think so. The TFT (trans fluid temp) is integral to the TFP (trans fluid pressure switch) which is located inside the trans.

Pressure is to be taken here.

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