3rd 4l80 now
02-24-2005, 10:50 AM
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3rd 4l80 now need help Im on my 3rd 80 now, the first one lasted 120k. The second one shifted fine for about 2k and then one morning, it started to slip alittle and then felt fine. Then it started making noise in first and started shifting hard, at the next stop light there was nothing. For the 3rd one it lasted about 2500-3k and did the same as the 2nd tranny. The thing had been shifting fine and then yesterday after getting gas it started shifting really hard and then shifted normal again. Getting ready to go back to work, i went to back out of my driveway and there was nothing. Lastnight i dropped the pan and the fluid was alittle dark, but didnt smell burned. I put in a new filter and oil, just to see if maybe that would help and it still had nothing. Any ideas on what might be going on? maybe a bad tune? Just before the first one went out, i put in another mail order tune and it let go about 2k miles after putting in the new tune. For the 3rd one, i put back in the stack stall and also put in a 10x18 tranny cooler with a 10''fan on it.
Last edited by BLK6.0HD; 02-24-2005 at 11:40 AM.
02-24-2005, 01:02 PM
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Have you been reusing the converter (which is a nice crud-
reservoir, if the first trans died a violent death)?
Any codes that might indicate a problem with the controls
rather than the mechanicals? No mention of any hard use,
to make it break, but a wire can so easily be messed up.
reservoir, if the first trans died a violent death)?
Any codes that might indicate a problem with the controls
rather than the mechanicals? No mention of any hard use,
to make it break, but a wire can so easily be messed up.
02-24-2005, 01:26 PM
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On the 2nd tranny i did reuse the converter, but for the third one i put back in the stock one a new cooler on it. Yesterday i had a friend at a chevy dealer try to pull any codes off it and there were none. I have been really easy on this tranny due to the fact i cant really afford to keep putting in trannies. The bottle was pulled of it after the first tranny died.
02-24-2005, 07:14 PM
#5
My '99 4L80E went out right over 60,000.
Rebuilt it myself.
Problem areas. Boost valves stick causing 500 + psi line pressure and blowing seals, breaking drums, cracking cases.
Pumps warp causing cross leaks and high line pressure.
High line pressure = hard shifts and broken parts.
I got lucky and only lost reverse. it slammed the reverse servo against the case enough to break it.
During the tear down I seen bushings worn in excess of 1/16", and thats at 60,000.
The problem IMO is you're not taking the trans apart and adressing the specific problem, the thing thats failing.
The forward sprag is weak, first (the initial apply into drive) second and third beat on this part.
I'd make sure the pump on the next one is flat sanded, wet air tested and have a Sonnax pressure limiting reverse boost valve. Install TransGo high temp stator rings.
Don't use the long gold stator support bolt, it's too long, gets tight without clamping down and causes a huge fluid leak if not properly installed.
Most important, find out what is failing.
Rebuilt it myself.
Problem areas. Boost valves stick causing 500 + psi line pressure and blowing seals, breaking drums, cracking cases.
Pumps warp causing cross leaks and high line pressure.
High line pressure = hard shifts and broken parts.
I got lucky and only lost reverse. it slammed the reverse servo against the case enough to break it.
During the tear down I seen bushings worn in excess of 1/16", and thats at 60,000.
The problem IMO is you're not taking the trans apart and adressing the specific problem, the thing thats failing.
The forward sprag is weak, first (the initial apply into drive) second and third beat on this part.
I'd make sure the pump on the next one is flat sanded, wet air tested and have a Sonnax pressure limiting reverse boost valve. Install TransGo high temp stator rings.
Don't use the long gold stator support bolt, it's too long, gets tight without clamping down and causes a huge fluid leak if not properly installed.
Most important, find out what is failing.
02-25-2005, 08:18 AM
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sounds like a bushing or seal (primarily pump ring) problem, Or build error. However it could be a press controll motor or leak internally. A pressure gauge is your friend. Take some readings and make sure there in spec. Its vital to know pressures when troubleshooting a trans. and will reveal many things.
