Transmission Anomaly...HOW IS THIS EVEN POSSIBLE?
May 6th, 2021, 12:50 AM
#1
Transmission Anomaly...HOW IS THIS EVEN POSSIBLE?
I'll get straight to the point. 2 weeks ago my 2000 Silverado lost all gears. Every gear is neutral. I've got it on jackstands with the rear wheels unobstructed and have been troubleshooting it off and on for the last 2 weeks. The pan has a new filter and new fluid. The tranny, torque convertor and transcooler lines still have the old, dark fluid in them and it doesn't smell burnt at all. Just dark. With the engine warmed up and the upper trans cooler line disconnected, no fluid comes out when I go thru the gears. Nor does the old fluid from the TC mix with the new fluid in the pan. Sounds like the pump is out. So how is it possible for me to put it in any forward gear, grab the drivers side rear wheel and spin it forward and it continues to spin at 5 mph until I either stop it with my hand, move it into neutral, or apply the brake? The passenger side stays still until I give it a spin and then it spins right along with the drivers side. If I shift it from 1st gear to 2nd, it actually picks up speed to nearly 10 mph. If I press the gas pedal the wheel slows down but doesn't stop. When I let off the gas it speeds back up to where it was. And still no cross contamination between the fluids. I'm not a transmission guy. I've been thru a couple of valvebodies but that's it. I'm sure there's a good explanation for my ghost transmission, but I cannot wrap my head around it. Someone please enlighten me. How is this transmission able to work with no fluid pumping thru it?
Last edited by Devil Rooster; May 7th, 2021 at 2:12 AM. Reason: To clarify my question.
May 7th, 2021, 11:45 AM
#2
CF Senior Member
Double check to make sure the transmission filter is still pressed into the valvebody. If it is not, then no fluid is going into the transmission to be pumped.
May 7th, 2021, 12:10 PM
#3
CF Veteran
Keep in mind the input shaft is still turning because it’s splined to the torque converter and doesn’t require fluid pressure.
The clutch packs all have return springs, so what’s probably happening is there’s just enough tension on the clutch packs to keep the wheels turning once you start them spinning, but not enough to overcome the inertia on its own. You’re going to grind the clutches down if you keep doing it.
When you changed the fluid and filter did you see any large, splinter sized metal particles in the pan?
The clutch packs all have return springs, so what’s probably happening is there’s just enough tension on the clutch packs to keep the wheels turning once you start them spinning, but not enough to overcome the inertia on its own. You’re going to grind the clutches down if you keep doing it.
When you changed the fluid and filter did you see any large, splinter sized metal particles in the pan?
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Devil Rooster (May 23rd, 2021)
May 8th, 2021, 5:03 PM
#5
[QUOTE=Gumby22;464651]Keep in mind the input shaft is still turning because it’s splined to the torque converter and doesn’t require fluid pressure.
And the torque converter's bolted to the flexplate which is bolted to the crank. That's what I'm looking for Gumby! That makes sense to me, related to what's going on. Thank you.
As for the pan and fluid condition, I've not seen anything larger than dust. The magnet had about 1/16" buildup and the fluid has a dark red hue around the edges and is opaque through the middle, looking through the gatorade bottle i saved it in. It doesn't smell brand new but it doesn't smell burnt at all. Just unusually dark with clutch material, I'm guessing. When I pulled the transmission back 18 mths ago to replace the rear main, i flushed the cooler lines and filter and topped it off with fresh fluid.
Does this sound like pump failure or could it possibly be something simpler?
And the torque converter's bolted to the flexplate which is bolted to the crank. That's what I'm looking for Gumby! That makes sense to me, related to what's going on. Thank you.
As for the pan and fluid condition, I've not seen anything larger than dust. The magnet had about 1/16" buildup and the fluid has a dark red hue around the edges and is opaque through the middle, looking through the gatorade bottle i saved it in. It doesn't smell brand new but it doesn't smell burnt at all. Just unusually dark with clutch material, I'm guessing. When I pulled the transmission back 18 mths ago to replace the rear main, i flushed the cooler lines and filter and topped it off with fresh fluid.
Does this sound like pump failure or could it possibly be something simpler?
Last edited by Devil Rooster; May 8th, 2021 at 6:37 PM. Reason: add information
May 10th, 2021, 12:20 PM
#6
CF Veteran
[QUOTE=Devil Rooster;464724]
It definitely sounds like an oil pressure problem, but that doesn’t necessarily condemn the pump.
Even in park or neutral, the primary hydraulic circuit supplies pressure to upwards of 5 solenoids and the Lo/Reverse clutch. When it comes to hydraulics, a loss of pressure at one point in the system will result in loss of pressure in the rest of the system - just like a brake fluid leak.
That said, neutral is the most isolated of the manual gears, so fluid pressure testing should be done in neutral to eliminate the most possibilities first. There’s a pressure tap for testing on the driver side of the transmission, near the range sensor. It looks like a regular plug in the side of the case - a basic oil pressure testing kit should have the correct adapters for checking it.
However it would be wise to check for codes first to see if there’s any stored for the pressure control solenoid. If all you’re getting is a generic P0700, you’ll need a scan tool or phone app capable of reading transmission specific codes.
I can’t recall the exact years, but there were some transmissions that had problems with trans fluid leaking into the valve body connectors (rear passenger side of trans). Function can be temporarily restored by disconnecting it and cleaning it using contact cleaner and compressed air, so it may be worth seeing if fluid has penetrated that connector. The only permanent fix is to replace the valve body harness.
Keep in mind the input shaft is still turning because it’s splined to the torque converter and doesn’t require fluid pressure.
And the torque converter's bolted to the flexplate which is bolted to the crank. That's what I'm looking for Gumby! That makes sense to me, related to what's going on. Thank you.
As for the pan and fluid condition, I've not seen anything larger than dust. The magnet had about 1/16" buildup and the fluid has a dark red hue around the edges and is opaque through the middle, looking through the gatorade bottle i saved it in. It doesn't smell brand new but it doesn't smell burnt at all. Just unusually dark with clutch material, I'm guessing. When I pulled the transmission back 18 mths ago to replace the rear main, i flushed the cooler lines and filter and topped it off with fresh fluid.
Does this sound like pump failure or could it possibly be something simpler?
And the torque converter's bolted to the flexplate which is bolted to the crank. That's what I'm looking for Gumby! That makes sense to me, related to what's going on. Thank you.
As for the pan and fluid condition, I've not seen anything larger than dust. The magnet had about 1/16" buildup and the fluid has a dark red hue around the edges and is opaque through the middle, looking through the gatorade bottle i saved it in. It doesn't smell brand new but it doesn't smell burnt at all. Just unusually dark with clutch material, I'm guessing. When I pulled the transmission back 18 mths ago to replace the rear main, i flushed the cooler lines and filter and topped it off with fresh fluid.
Does this sound like pump failure or could it possibly be something simpler?
Even in park or neutral, the primary hydraulic circuit supplies pressure to upwards of 5 solenoids and the Lo/Reverse clutch. When it comes to hydraulics, a loss of pressure at one point in the system will result in loss of pressure in the rest of the system - just like a brake fluid leak.
That said, neutral is the most isolated of the manual gears, so fluid pressure testing should be done in neutral to eliminate the most possibilities first. There’s a pressure tap for testing on the driver side of the transmission, near the range sensor. It looks like a regular plug in the side of the case - a basic oil pressure testing kit should have the correct adapters for checking it.
However it would be wise to check for codes first to see if there’s any stored for the pressure control solenoid. If all you’re getting is a generic P0700, you’ll need a scan tool or phone app capable of reading transmission specific codes.
I can’t recall the exact years, but there were some transmissions that had problems with trans fluid leaking into the valve body connectors (rear passenger side of trans). Function can be temporarily restored by disconnecting it and cleaning it using contact cleaner and compressed air, so it may be worth seeing if fluid has penetrated that connector. The only permanent fix is to replace the valve body harness.
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Devil Rooster (May 23rd, 2021)
May 16th, 2021, 6:37 AM
#7
[QUOTE=Gumby22;464873]
It definitely sounds like an oil pressure problem, but that doesn’t necessarily condemn the pump.
Even in park or neutral, the primary hydraulic circuit supplies pressure to upwards of 5 solenoids and the Lo/Reverse clutch. When it comes to hydraulics, a loss of pressure at one point in the system will result in loss of pressure in the rest of the system - just like a brake fluid leak.
That said, neutral is the most isolated of the manual gears, so fluid pressure testing should be done in neutral to eliminate the most possibilities first. There’s a pressure tap for testing on the driver side of the transmission, near the range sensor. It looks like a regular plug in the side of the case - a basic oil pressure testing kit should have the correct adapters for checking it.
However it would be wise to check for codes first to see if there’s any stored for the pressure control solenoid. If all you’re getting is a generic P0700, you’ll need a scan tool or phone app capable of reading transmission specific codes.
I can’t recall the exact years, but there were some transmissions that had problems with trans fluid leaking into the valve body connectors (rear passenger side of trans). Function can be temporarily restored by disconnecting it and cleaning it using contact cleaner and compressed air, so it may be worth seeing if fluid has penetrated that connector. The only permanent fix is to replace the valve body harness.
Your post gave me a little hope, unfortunately it didn't help me find the answer I wanted. But it did help me get the answer I needed. Unless I've missed something I think we can condemn the pump now.
The scan pulled 40 powertrain codes starting with p0121 thru the 130's, 40's, 50's, 60's and 70's, then skipped to p0300's, 400's, 500's and ended with p0711, 713 & 740. Never got the p0700. In addition to those 40, I pulled 10 ABS Codes from c0222 thru c0265, but that's a known issue I've been procrastinating on.
Fluid pressure testing was a bust. The needle never moved nor has the fluid level on the dipstick moved. And still no cross contamination between the new and old fluid
When I dropped the pan, one thing I noticed was all the solenoids were pretty well coated in the same gray slime found on the pan magnet, which I'm guessing is clutch material. I pulled them all, including the wiring harness, flushed, cleaned and tested each one. The shift solenoids showed resistance in the low 20's and opened and closed, when energized, with strength similar to the new one I bought to use for comparison. I replaced the pwm due to a broken connector, the 3-2 down shift due to a bad decision, and the pressure switch manifold. Something catastrophic happened to the pressure switch manifold. The plastic plate that covers the o-rings, seperated from the manifold along one edge and looks like it started to melt. The plate looked like a wave instead of being flat. Three of the o-rings were shredded. The lockup solenoid tested low 20's on resistance and loosened up inside after I flushed it out. The wiring harness will need to be replaced due to a missing locking tab and fluid bypass. I thoroughly cleaned and dried both sides before reconnecting. I did not test the EPC but I did clean it really good and made it very shiny.
If my conclusion is correct and a full r&r is the only option, then I think it's worth pointing out, for anyone trying to learn something from this thread, that testing in the proper order would have likely led me to this conclusion BEFORE I waisted my time and money replacing two solenoids, a pressure manifold, 2 gallons of trans fluid and a filter. The replacement cost will be in the neighborhood of $1700, or I could save a little and pull it and stab it myself. But I'm having a hard time justifying putting that kind of money into a 2000 Silverado work truck with 307,728 miles on it. Chevy built this truck right.
LOL!!!
Or do I need to go back and test that EPC?
It definitely sounds like an oil pressure problem, but that doesn’t necessarily condemn the pump.
Even in park or neutral, the primary hydraulic circuit supplies pressure to upwards of 5 solenoids and the Lo/Reverse clutch. When it comes to hydraulics, a loss of pressure at one point in the system will result in loss of pressure in the rest of the system - just like a brake fluid leak.
That said, neutral is the most isolated of the manual gears, so fluid pressure testing should be done in neutral to eliminate the most possibilities first. There’s a pressure tap for testing on the driver side of the transmission, near the range sensor. It looks like a regular plug in the side of the case - a basic oil pressure testing kit should have the correct adapters for checking it.
However it would be wise to check for codes first to see if there’s any stored for the pressure control solenoid. If all you’re getting is a generic P0700, you’ll need a scan tool or phone app capable of reading transmission specific codes.
I can’t recall the exact years, but there were some transmissions that had problems with trans fluid leaking into the valve body connectors (rear passenger side of trans). Function can be temporarily restored by disconnecting it and cleaning it using contact cleaner and compressed air, so it may be worth seeing if fluid has penetrated that connector. The only permanent fix is to replace the valve body harness.
The scan pulled 40 powertrain codes starting with p0121 thru the 130's, 40's, 50's, 60's and 70's, then skipped to p0300's, 400's, 500's and ended with p0711, 713 & 740. Never got the p0700. In addition to those 40, I pulled 10 ABS Codes from c0222 thru c0265, but that's a known issue I've been procrastinating on.
Fluid pressure testing was a bust. The needle never moved nor has the fluid level on the dipstick moved. And still no cross contamination between the new and old fluid
When I dropped the pan, one thing I noticed was all the solenoids were pretty well coated in the same gray slime found on the pan magnet, which I'm guessing is clutch material. I pulled them all, including the wiring harness, flushed, cleaned and tested each one. The shift solenoids showed resistance in the low 20's and opened and closed, when energized, with strength similar to the new one I bought to use for comparison. I replaced the pwm due to a broken connector, the 3-2 down shift due to a bad decision, and the pressure switch manifold. Something catastrophic happened to the pressure switch manifold. The plastic plate that covers the o-rings, seperated from the manifold along one edge and looks like it started to melt. The plate looked like a wave instead of being flat. Three of the o-rings were shredded. The lockup solenoid tested low 20's on resistance and loosened up inside after I flushed it out. The wiring harness will need to be replaced due to a missing locking tab and fluid bypass. I thoroughly cleaned and dried both sides before reconnecting. I did not test the EPC but I did clean it really good and made it very shiny.
If my conclusion is correct and a full r&r is the only option, then I think it's worth pointing out, for anyone trying to learn something from this thread, that testing in the proper order would have likely led me to this conclusion BEFORE I waisted my time and money replacing two solenoids, a pressure manifold, 2 gallons of trans fluid and a filter. The replacement cost will be in the neighborhood of $1700, or I could save a little and pull it and stab it myself. But I'm having a hard time justifying putting that kind of money into a 2000 Silverado work truck with 307,728 miles on it. Chevy built this truck right.
LOL!!!
Or do I need to go back and test that EPC?
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May 16th, 2021, 8:32 AM
#8
CF Veteran
Most of those codes are probably history (not active). The P0700 only sets when there’s a separate TCM and the PCM doesn’t directly store transmission codes.
Clutch material is either brown or black and gritty. The gray slime is metal “dust” that’s mixed with fluid.
I agree a replacement or rebuild are your options. If you’re going to attempt it yourself, I’d recommend getting a service manual as it’s easy to get “lost in the parts” so to speak. Cleanliness and organization are your best friends.
Clutch material is either brown or black and gritty. The gray slime is metal “dust” that’s mixed with fluid.
I agree a replacement or rebuild are your options. If you’re going to attempt it yourself, I’d recommend getting a service manual as it’s easy to get “lost in the parts” so to speak. Cleanliness and organization are your best friends.
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Devil Rooster (May 23rd, 2021)
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