4L80 is singing and slipping...
11-09-2008, 02:28 PM
#1
4L80 is singing and slipping...
I went to the track yesterday, made 3 passes no problems at all. Drove back to town (~30 miles), met my family for dinner then proceeded to drive home (~10 miles). About 2 miles from my house, driving normally, I started hearing this high pitched whine. At first I though it was my supercharger but sounded completely different. Then thought it may be a bearing in alt or one of my idler pulleys. Get to a red light a few blocks from the house and I will be darned if the tranny didn't slip as I was leaving the light and seemed to hold second gear longer. So I put it in neutral and gave it a rev and still whining. Next few turns into the neighborhood, tranny still seems to be slipping a bit. Popped the hood in the driveway and I couldn't hear the noise under the hood but could hear it in cab and under the truck upon reving the engine in park.
This morning I went out to check fluid level, all connections for leaks or disconnections. All of that looked good. Cranked the truck while on jackstands, noise is still there. Whine is definitely under the truck but can only hear it above 1500 rpm so it was hard to pinpoint it as my arms are only so long to reach the accelerator. For grins, I pulled the serpentine and a/c belts, cranked the truck and noise was gone. I removed and inspected the tensioner pulley as it was a little noisy when I spun it. So I tried again installing one belt at time, still no noise. So I decide to take it for a little test drive, got to the end of my road and whine returns. Get out of my neighborhood and trans starts slipping again. Went a few blocks and turned around. It slips a bit in first, shifts very softly, slips bad in second and holds out second gear a long time. It got progressively worse the more I drove it. But the time I got home the converter would not lock up and may not even be getting out of second gear. Once I got back in the driveway, I held the brake and reved in gear, didn't even try to go forward and seemed to just free rev up to 4k.
To describe the whine, sounds like a bearing or alternator noise from a bad ground in the stereo. It is directly related to engine rpm and pitch gets higher with increasing rpm.
CLIFF NOTES:
Trans started whining and slipping on the way home from the track yesterday. Trans holds gears longer and shifts much softer. Fluid level is fine and all connections show no signs of leaking. Trans is stock low mile 4L80 with Transgo HD2 shift kit and Fuddle 3600 9.5" converter.
I am guessing either pump or converter. What sort of gauge and setup do I need to check fluid pressure? Could it be valve body related? Any other ideas??
This morning I went out to check fluid level, all connections for leaks or disconnections. All of that looked good. Cranked the truck while on jackstands, noise is still there. Whine is definitely under the truck but can only hear it above 1500 rpm so it was hard to pinpoint it as my arms are only so long to reach the accelerator. For grins, I pulled the serpentine and a/c belts, cranked the truck and noise was gone. I removed and inspected the tensioner pulley as it was a little noisy when I spun it. So I tried again installing one belt at time, still no noise. So I decide to take it for a little test drive, got to the end of my road and whine returns. Get out of my neighborhood and trans starts slipping again. Went a few blocks and turned around. It slips a bit in first, shifts very softly, slips bad in second and holds out second gear a long time. It got progressively worse the more I drove it. But the time I got home the converter would not lock up and may not even be getting out of second gear. Once I got back in the driveway, I held the brake and reved in gear, didn't even try to go forward and seemed to just free rev up to 4k.
To describe the whine, sounds like a bearing or alternator noise from a bad ground in the stereo. It is directly related to engine rpm and pitch gets higher with increasing rpm.
CLIFF NOTES:
Trans started whining and slipping on the way home from the track yesterday. Trans holds gears longer and shifts much softer. Fluid level is fine and all connections show no signs of leaking. Trans is stock low mile 4L80 with Transgo HD2 shift kit and Fuddle 3600 9.5" converter.
I am guessing either pump or converter. What sort of gauge and setup do I need to check fluid pressure? Could it be valve body related? Any other ideas??
11-09-2008, 02:38 PM
#3
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from my experience with losing the pump, the truck wouldn't be able to move at all as far as i know because there is no fluid pressure to engage the clutches, but the 80E could be different from my little 60E. could be the converter. i'm not too savvy on the workings of these things but i would think that could be a likely source. have you changed the fluid in the tranny at all? if its got a some debris in it i would think it would be the tranny, if not i would say the verter.
11-09-2008, 02:53 PM
#4
My guess is converter and shavings got in the pump.
That's what happened to me on my way to san diego recently. It would stall up on take off and then seemingly jerk into gear. Got worse every time i stopped. Eventually all I had left was 1st gear.
So you need both.
That's what happened to me on my way to san diego recently. It would stall up on take off and then seemingly jerk into gear. Got worse every time i stopped. Eventually all I had left was 1st gear.
So you need both.
11-09-2008, 05:44 PM
#5
If you have a pump or converter causing the noise, I would suspect that the trans is full of debris. Sounds like you better have that thing gone through while you have it out. No telling what damage has been done at this point with it slipping as well. Vince
11-09-2008, 07:14 PM
#6
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With a 9.5" 3600 stall it's sounding a little familar. Mine didn't make any noise but same symptoms. Took the clutches out of the converter and that pluged up the filter and it wouldn't move. Apparently lock up converters don't like loose stall and big HP in heavy vehicles. For a fix I went with a 4L80E 10" 3000 stall and programed the tow/haul to shut out the lock up.....we'll see!
11-09-2008, 08:03 PM
#7
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Sounds like what mine is doing right now. Don't even feel the shift from first to second. Holds second and doesn't want to let go. When in third it revs to about 3,000 rpms before it grabbing the gear. Never goes into fourth. I got a new trans and verter on the way.
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11-10-2008, 07:47 AM
#8
A couple of diagonistic questions:
-If the converter clutch came apart, would there be evidence of it in the trans pan?
-I had problems with the o-ring on the input shaft when first installing this converter. If that o-ring were torn or damaged in some way, would it cause these problems or would that just cause the converter to not lock up?
-I had an old style HD2 kit which required me to mash the plug in the seperator plate. If that plug came out, would it cause these symptoms?
-If the converter clutch came apart, would there be evidence of it in the trans pan?
-I had problems with the o-ring on the input shaft when first installing this converter. If that o-ring were torn or damaged in some way, would it cause these problems or would that just cause the converter to not lock up?
-I had an old style HD2 kit which required me to mash the plug in the seperator plate. If that plug came out, would it cause these symptoms?