Im stumpped

[chengny]

Have you checked your pump pressures?

This thread has become epic - I tried looking through all the replies to see what your pump was putting out. I didn't get too far so forgive me if ths is redundant:

You need a 300 psi gage with a long enough hose that you can sit it on your lap while test driving.



Oil pressure can be checked with the transmission in the vehicle, using a 0 to 300 psi pressure gauge.

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1.Clean dirt from line pressure plug, located on left side of transmission case, and remove plug.
2.Connect pressure gauge hose fitting at pressure plug bore in case and place gauge in vehicle so it can be seen from the driver's seat.
3.Drive vehicle until transmission fluid has reached operating temperature.
4.Check and correct fluid level.
5.Road test car and check pressure as follows:
Engine Idle Pressure Check
With selector lever in Direct Drive position, operate vehicle at approximately 30 mph with throttle closed. Line pressure should be 70 psi. When a selector lever has been moved to Intermediate range with vehicle operating at a stead road load (25mph), line pressure should e 150 psi (plus or minus 5 psi).

Pull Throttle Pressure Check
With vehicle on jackstands, disconnect vacuum line from carburetor and place selector lever in Neutral and in Reverse. Operate engine at fast idle (700-1000 RPM) in each position. Neutral pressure should be 145 psi, and Reverse pressure 230 psi. Connect vacuum line.

If either pressure check was low, check vacuum modulator for loose attaching bolt, collapsed bellows, or stuck modulator valve. Also check pressure regulator valve and spring for sticking, plugged orifice, or collapsed spring. Check regulator boost valve for sticking.

If either pressure check was too high, check vacuum line and vacuum modulator for leaks or sticking valve. Also check pressure regulator valve and boost valve for sticking.

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[Paulscrawler78]

The only issue with this test is my transmission is a 700r4 that does not have a vacume modulator

 

[Jims86]

Have you checked your pump pressures?

This thread has become epic - I tried looking through all the replies to see what your pump was putting out. I didn't get too far so forgive me if ths is redundant:

You need a 300 psi gage with a long enough hose that you can sit it on your lap while test driving.



Oil pressure can be checked with the transmission in the vehicle, using a 0 to 300 psi pressure gauge.

You must be registered for see images attach

1.Clean dirt from line pressure plug, located on left side of transmission case, and remove plug.
2.Connect pressure gauge hose fitting at pressure plug bore in case and place gauge in vehicle so it can be seen from the driver's seat.
3.Drive vehicle until transmission fluid has reached operating temperature.
4.Check and correct fluid level.
5.Road test car and check pressure as follows:
Engine Idle Pressure Check
With selector lever in Direct Drive position, operate vehicle at approximately 30 mph with throttle closed. Line pressure should be 70 psi. When a selector lever has been moved to Intermediate range with vehicle operating at a stead road load (25mph), line pressure should e 150 psi (plus or minus 5 psi).

Pull Throttle Pressure Check
With vehicle on jackstands, disconnect vacuum line from carburetor and place selector lever in Neutral and in Reverse. Operate engine at fast idle (700-1000 RPM) in each position. Neutral pressure should be 145 psi, and Reverse pressure 230 psi. Connect vacuum line.

If either pressure check was low, check vacuum modulator for loose attaching bolt, collapsed bellows, or stuck modulator valve. Also check pressure regulator valve and spring for sticking, plugged orifice, or collapsed spring. Check regulator boost valve for sticking.

If either pressure check was too high, check vacuum line and vacuum modulator for leaks or sticking valve. Also check pressure regulator valve and boost valve for sticking.

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700r4 is what he is dealing with.

 

[chengny]

Yeah admittedly, thats kind of a generic go/nogo test.

But,
The TV cable should not be thought of as an automatic downshift cable. It controls line pressures, shift points, shift feel, part throttle downshifts, and detent downshifts. The function of the cable is similar to the combined functions of a vacuum modulator and detent downshift cable. The TV cable operates throttle lever and bracket assembly, Figs. 1 and 2.

Then it goes on about adjusting the cable - you've done that - a lot I gather.

It continues:

4.Road test vehicle. If delayed or only full throttle shifts still occur, proceed as follows:

a.Remove oil pan and inspect throttle lever and bracket assembly, Fig. 4.
b.Check TV exhaust valve lifter rod for distortion, or binding in control valve assembly or spacer plate.
c.Make sure TV exhaust check ball moves up and down in conjunction with lifter.
d.Make sure lifter spring holds lifter rod up against control valve assembly.
e.Make sure TV plunger is not stuck.
f.Inspect transmission for correct throttle lever to cable link, Fig. 5.

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Following is excerpted from TSB
GMC NUMBER: 91-7A-139

GROUP: 7A Automatic Transmission
SUBJECT:
HYDRA-MATIC 4L60 (THM 700-R4) TRANSMISSION 3-4 CLUTCH/2-4 BAND

MODELS:
1982-1991 S/T, C/K, R/V 1-2 SERIES TRUCKS


Its specific to 4L60 & 700-R4

Debris inside the transmission can cause problems for the 3-4 clutch and 2-4 band. During any overhaul procedure, keep the area clean and clean all parts well before reinstalling them. Here are a few areas to pay special attention to when servicing a transmission for a 3-4 clutch or 2-4 band condition:

- Third Accumulator Exhaust Check-ball and Retainer

Located in the case servo bore, this check-ball can get sediment stuck in it which doesn't allow the ball to seat. This can cause the band to drag or the 3-4 clutch to not fully apply on a 2-3 upshift.

From post #352:

Ya so I think I'll need to readjust the TV cable on mine because it don't go into od till 60 1st changes into second around 15 and 2nd to 3rd around 35-40 all with light throttle
- Third Accumulator Orifice Cup Plug

Also located in the case servo bore, this orifice must be kept unblocked. If sediment blocks the orifice, the third accumulator will not fill properly due to trapped air in the cavity. This can cause apply and release conditions with the 3-4 clutch. The orifice cup plug also lubes the 2-4 band through the band's lube window.


- 3-4 Clutch Exhaust Check-ball and Retainer

Located in the input housing, this check-ball helps exhaust the 3-4 clutch. It the check-ball cannot seat, the 3-4 clutch cannot fully apply. If the check-ball is stuck in the seated position, the 3-4 clutch cannot fully exhaust.


700R4 test pressures:

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[HotRodPC]

I understand all the pressures and what the TV cable does, but in his case, all the pressure test will prove is, YEP, something is wrong, which we know already due to the shifting issues and it's to be expected. Get this TV cable fixed and pressures will be correct. Still good info to have around.

 

[Paulscrawler78]

Yes and for all that info thank you. Hopefully the weather holds up this weekend so I can try to fix this damn thing

 

[Paulscrawler78]

I got the new filter again new transmission fluid and I also got the parts I need to put a drain plug in the damn transmission because I'm sick of spending 40 bucks each time I have to pull the pan off....I'll be working on it tomorrow as long as the weather holds up I'll be pulling the pan to see what I scrwed up and also to check the valve bore for any debre

 

[HotRodPC]

Fluids are to damn expensive these days to waste. I'd have a pan big enough, and let the pan down at one corner first to catch 75% or more of the fluid. It can be done. I'd then reuse it if it's not burnt in any way. Also, unless you see a bunch of junk in the pan or on the filter, I'd use the same filter. Just to pull the pan, you shouldn't need over a gallon of fluid I wouldn't think.

 

[89Suburban]

Yah, where is all the fluid going when you drain it?

 

[Paulscrawler78]

To be recycled..... Larry I need u to call me asap I think I know what's wrong with the transmission but idk for sure and our the only guy I know that knows these transmissions

 

[HotRodPC]

Gimme Idea what you think, so I can research it a bit. Before we get together. It's been a long time since I had one of these apart and I don't want to be getting confused with a Th350. I just back in form outside, getting ready to split for the other job.

 

[Paulscrawler78]

Found the problem and fixed said problem.....the problem I had was the spring for the TV valve shrunk so I stretched it out to figure out if that was the problem and low and behold trans shifts fantastic so tomorrow I'll call transmission shops and see if I can get just that spring

 

[Paulscrawler78]

i also readjusted the tv cable and that actually adjusted out how far it should as default settings it shifts smooth and through all gears with no problem at all im super happy

 

[HotRodPC]

That sounds great. I figured it had to do with the TV linkage, Valve or something in there. Hopefully no harm to the trans. Fluid still looking good that you pulled out? BTW, I wouldn't have recycled if it looked good. Fluids are to damn much these days. If it was red, I'd have ran it through a screen filter and re used it.
I"ll do some looking around too and see if I have a loose spring. Maybe if you have a pic of one. It's been so long since I've opened one up I don't even know what it looks for sure. I'd know if I seen it I think, but to be sure...

 

[Paulscrawler78]

I did not take a pic but its about 2 1/2 inches long about 1/2 inches round mine was painted yellow I'll be calling tranny shops tomorrow to see if they have any