4l80e no fourth
4l80e no fourth we have a comeback at work, the transmission has been in this van for about 6 months with no problems. We got it back today, it has no fourth gear. (i didnt build it.) When it goes to apply fourth gear all it does is neutralize, we hooked up the transX and shifted it with that and it still does the same thing. That rules out an ECM problem. We dont think the clutch pack is going because the fluid is clean. The owner changed the fluid in it recently due to the above problem, and found nothing in the fluid, just nice clean red fluid.
We are guessing there may be a leak in the circuit for the 4th clutch. A look at the clutch and band application chart shows that the only clutch not used for the rest of the gears is the 4th clutch, maybe the 4th clutch piston is cracked and is leaking? The guy who built it cant remember if he replaced the piston with an aluminum one or reused the plastic one.
im going to change out the solenoids tomorrow and see if anything changes. The solenoids are working. Solenoid A is on and Solenoid B is off for First, Solenoid A and B are off for second, Solenoid A is off and Solenoid B is on for Third, Both A and B are on for fourth. One builder we talked to said he had heard of this problem once and it was the solenoids, so its worth a shot. Need to try something before we have this guy pull it out and we tear it down, again.
Maybe some gurus can shed some light.
We are guessing there may be a leak in the circuit for the 4th clutch. A look at the clutch and band application chart shows that the only clutch not used for the rest of the gears is the 4th clutch, maybe the 4th clutch piston is cracked and is leaking? The guy who built it cant remember if he replaced the piston with an aluminum one or reused the plastic one.
im going to change out the solenoids tomorrow and see if anything changes. The solenoids are working. Solenoid A is on and Solenoid B is off for First, Solenoid A and B are off for second, Solenoid A is off and Solenoid B is on for Third, Both A and B are on for fourth. One builder we talked to said he had heard of this problem once and it was the solenoids, so its worth a shot. Need to try something before we have this guy pull it out and we tear it down, again.
Maybe some gurus can shed some light.
mine did that when the transbrake install was done and my builder drilled a hole over too far and it was leaking pressure. I know that doesnt help but it was easy to find cause a 4l80e isnt supposed to be able to nuetral 4th gear i dont think
i didn't pull the pan like i said i was going too, had the guy pull it out instead. There was a bad solenoid, whats odd is that it was a brand new solenoid and it looked like it was stretched out. It is really loose. There is a sonnex update for the valve that solenoid. We think the valve is over powering the solenoid and putting a large amount of pressure on it, pushing it outward, making the solenoid stretch.
we are going to replace the solenoid, do the sonnex update on the valve and do the sonnex update on the accumulators and give it back to the customer.
we are going to replace the solenoid, do the sonnex update on the valve and do the sonnex update on the accumulators and give it back to the customer.
