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Discussion Starter · #1 ·
Hi Guys:

When I went to town this morning I noticed the tranny, 4L60E, seemed to be shifting softly and later than it was when I took my wife to work 2 hours earlier.

I checked the fluid and it is red and didn't smell burned. The tranny pulls into Drive from Neutral with its usual satisfying clunk but then seems to be softer on the take off and feels like it is reving a little higher at a given speed than it did.

This is the second tranny in the car. It was build by a very reputable shop and has run beautifully with a custom 2100 stall HD convertor. The oem tranny went out at 65K kms and pretty much destroyed everything but the case and the valve body. This tranny has about 90K kms on it as has been running just fine until this morning. I took the car to Ottawa last week (2000 km round trip) and there was nary a problem.

I'll be dropping the pan this weekend to see if there is crap in it but first off:

Are there any other things that I can look for that could cause the tranny to suddenly start to shift softer (not exactly a rolling shift but close) and later? Like maybe the TPS or a temp sensor malfunctioning.

Any and all help is appreciated.

Thanx guys, Stewart
 

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If the TPS is reading low or the fluid is cold, then yes it will shift more softly. The other thing is that the line pressure may have just suddenly gone low. Test gauges are available on Ebay for around $60 last time I checked. Plumb it into the pressure test port and then ziptie the gauge to a windshield wiper like a hood tach and see what you get while driving around.
 

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Discussion Starter · #3 ·
If the TPS is reading low or the fluid is cold, then yes it will shift more softly. The other thing is that the line pressure may have just suddenly gone low. Test gauges are available on Ebay for around $60 last time I checked. Plumb it into the pressure test port and then ziptie the gauge to a windshield wiper like a hood tach and see what you get while driving around.
Hi Joel:

The temp was operating normal and the fluid was at proper level. What would cause the pressure to go low?

Stewart
 

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No. If your 4L60E is broke, then fix it. Do a 6-speed because you really want to.

Search "line pressure" and you'll get a bunch of non-fatal things you can fix before you delve into a 6-speed stick shift conversion.
 

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Discussion Starter · #7 ·
No. If your 4L60E is broke, then fix it. Do a 6-speed because you really want to.

Search "line pressure" and you'll get a bunch of non-fatal things you can fix before you delve into a 6-speed stick shift conversion.
Hi Joel:

The first time the tranny went out it cost me $3K to repair it and that was about 12 years ago. If it's going to cost me another $3K the 6 speed isn't going to be that much more.

I'll do the search and see what I can find. Thanx for the heads-up. I hope it's not something major but I'm not holding my breath.

Stewart
 

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when my trans went out earlier this year I checked around and the average price seemed to be about $1500 for a rebuild
 

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Discussion Starter · #9 ·
when my trans went out earlier this year I checked around and the average price seemed to be about $1500 for a rebuild
Not a bad price but remember I'm north of the border and in a rural area. No dedicated tranny shops around here close by.

Stewart
 

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Discussion Starter · #10 ·
Joel:

I checked out your sticky and think immediately that I may have problem #16, low line pressure. I'm going to change the fluid and filter this weekend and check for any chafed wires, etc. Hopefully that is going to solve my problem.

Just for the sake of repeating; the take off is soft, my shifts are soft, almost rolling, and the performance is dropping; I have all shifts but the converter doesn't seem to lock when cruising, so I have a cruise rpm a little higher than normal.

Thanx, Stewart
 

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Stewart, let me be clear that if your option is $3000 after a 4L60E vs. $3000 towards a T56 that you've been WANTING to do, then there's no question you'd be wiser to put money towards the T56.

But, if you're mechanically inclined, you can do a good bit of troubleshooting on the 4L60E for maybe $250 total before declaring it dead.

Like I said, buy a line pressure gauge off Ebay and see what it's doing. If you have good base pressure but lousy rise, then you can often ameliorate that. More than anything else, replace the boost valve, the EPC solenoid and the EPC solenoid filter screen on the spacer plate. If it's still driving lousy, then you can call it quits and go shopping for a T56.
 

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Stewart,

If it come to it.....give Shane a call and see what he can do about getting one of his Level-1 trannies to you.

NO NEED to pay premium dollars to have some guy of 'suspect' skills rebuild a tranny for ya!

IMHO, of course :) .

http://www.cpt4l60-e.com/products.html

KW
 

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Discussion Starter · #13 ·
Stewart, let me be clear that if your option is $3000 after a 4L60E vs. $3000 towards a T56 that you've been WANTING to do, then there's no question you'd be wiser to put money towards the T56.

But, if you're mechanically inclined, you can do a good bit of troubleshooting on the 4L60E for maybe $250 total before declaring it dead.

Like I said, buy a line pressure gauge off Ebay and see what it's doing. If you have good base pressure but lousy rise, then you can often ameliorate that. More than anything else, replace the boost valve, the EPC solenoid and the EPC solenoid filter screen on the spacer plate. If it's still driving lousy, then you can call it quits and go shopping for a T56.
Hi Joel:

I don't know how mechanically inclined I'd have to be to take on auto tranny repairs. My experience with them so far is changing a torque converter, fluid and filter changes and installing a few "shift kits". I've built engines, redone rear rear ends, brake systems and re-built carbs, etc, but minimal work inside an auto trans.

Are the boost valve and EPC filter and solenoid things that can be done without stripping the trans? I've got to do some more research. I've got the factory service manuals so they're a good start.

First stupid question, what does "EPC" stand for, where is it found and what does it do?

Thanx for the help.

Stewart
 

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Discussion Starter · #14 ·
Stewart,

If it come to it.....give Shane a call and see what he can do about getting one of his Level-1 trannies to you.

NO NEED to pay premium dollars to have some guy of 'suspect' skills rebuild a tranny for ya!

IMHO, of course :) .

http://www.cpt4l60-e.com/products.html

KW
Hi KW:

That is a possibility since I have a US delivery address which will save me some shekels. But right now I'm really hoping this is something relatively minor I can correct without having to replace the trans again or have to get it completely re-built.

Thanx for the input.

Stewart
 

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Discussion Starter · #15 · (Edited)
Research and Update

Joel:

I've been through my service manual and now know what the EPC is. It's called a the Pressure Control Solenoid in the GM manual and is easily accessed with the pan off.

I can't find any reference to to a boost valve. Is it the 1-2 accumulator valve located under the the solenoid?

I also see there is a filtered accumulator feed hole in the spacer plate, which leads me to believe the valve body must come off to replace/clean it.

How am I doing so far?

Before I did all this I checked all fuses and wires that I could find that are on the same circuit as the tranny and everything looks good with no chafing.

FWIW, the fluid is still red and doesn't smell burned but has a very slightly acrid edge that I've never smelled before. I'm thinking that if the pressure was low there would be slippage of the clutches/bands that is causing the change in smell. I hope I've caught this early enough to save the trans from a major rebuild right now and that it is only a solenoid.

I haven't checked the line pressure because I don't have a gauge. Once the holiday weekend is over I'll be doing more.

One other question, are there any check balls in the 4L60E trans or is it completely electronic?

Stewart
 

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Discussion Starter · #16 ·
Update

I haven't had time to get to the trans because of family visiting and I'm still waiting for my pressure gauge. Hopefully this weekend I can get it sorted out.

Stewart
 

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1. The boost valve is in the bottom of the pump on the driver's side of the car. it is also known as the 'reverse boost' valve. It can be accessed from the pan area.
2. there are checkballs in the spacer plate area. The 1-2 checkball gets used the most and tends to oval out the hole, and sometimes even gets lodged in the plate. You can buy a Fitzall VB-101 kit for $5 or so that has repair sleeves. I used these all the time.
3. yes, you'll have to drop the valvebody to clean out or replace the screen. Be gentle on the valvebody gaskets as they get brittle with age. They are pretty cheap from the GM dealer though and may be available from parts houses too.

FWIW, if you drive the car gently through the shifts, you probably won't do any damage to the trans. I've babied hurt 4L60Es for a very long time.
 

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Discussion Starter · #18 ·
1. The boost valve is in the bottom of the pump on the driver's side of the car. it is also known as the 'reverse boost' valve. It can be accessed from the pan area.
2. there are checkballs in the spacer plate area. The 1-2 checkball gets used the most and tends to oval out the hole, and sometimes even gets lodged in the plate. You can buy a Fitzall VB-101 kit for $5 or so that has repair sleeves. I used these all the time.
3. yes, you'll have to drop the valvebody to clean out or replace the screen. Be gentle on the valvebody gaskets as they get brittle with age. They are pretty cheap from the GM dealer though and may be available from parts houses too.

FWIW, if you drive the car gently through the shifts, you probably won't do any damage to the trans. I've babied hurt 4L60Es for a very long time.
Thanx Joel:

Now I can see what and where it is in the pic in the service manual. Once I get my pressure tester I'll be in a better place to finalize my solution.

Stewart
 

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Look for a solid 65-70 psi in P, N, or D at idle. Reverse should kick up to 110-150psi. From a dead stop, a WOT run should cause the gauge at least 200psi sometime before it shifts. It is normal to see quite a bit of fluctuation during normal driving. I unplug my wiper motor harness and then ziptie the gauge to the windshield wiper like a hood tach and drive it around to see what it does. On my cars, I leave it on for a week (provided it doesn't rain) and just keep an eye on it. You start to get a feel for what it's doing. If you see a big drop going into any particular gear, that can be a sign of a leak in that particular apply circuit.
 

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Discussion Starter · #20 ·
Look for a solid 65-70 psi in P, N, or D at idle. Reverse should kick up to 110-150psi. From a dead stop, a WOT run should cause the gauge at least 200psi sometime before it shifts. It is normal to see quite a bit of fluctuation during normal driving. I unplug my wiper motor harness and then ziptie the gauge to the windshield wiper like a hood tach and drive it around to see what it does. On my cars, I leave it on for a week (provided it doesn't rain) and just keep an eye on it. You start to get a feel for what it's doing. If you see a big drop going into any particular gear, that can be a sign of a leak in that particular apply circuit.
Good info. Thanx Joel.

Stewart
 
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