Pan magnet issues in 4L80 pan long!!!
06-29-2009, 10:06 AM
#1
Pan magnet issues in 4L80 pan long!!! Friday i was testing my car out ,4l80 with a Trans go MVB & Circle D 4400 stall,before i was going to load it to take to the track on Saturday, I stop and stall the car up to 3200 rpm with the two step engaged and launch it off the foot brake and crank it up to 7200 rpm and went to shift in to second gear and it would not go in , hit the rev limiter 7400 rpm when i let off the gas it shifted 
First i though it was the shift linkage so i tried it again did the same thing, So i put it in second gear and kick it down , the rpm climbed to a round 2500 rpm and went to neutral, let out of the gas and went in gear hard, all the other gears work fine to, Then i started to hear a whining noise, thinking Im losing the pump. I drove it home and hooked up my pressure gauge to the pressure port and the pressure was low around 100psi in all gears even with the vacuum modulator unhooked. So I dropped the pan every thing looked clean , no burnt smell or debre in the pan , I dropped the valve body and check the gaskets and the servo piston, I cleaned every thing and install new valve body gaskets. I looked in the pan before i cleaning it up and noticed the magnet was not were it supposed to be ,I took the new filter and placed it in the pan over the marks left from the old filter and ,WOLA ,, The magnet had slid in the pan under the pickup opening in the filter, Whats the odd of that. I moved the magnet to the back side of the pan and put it all back together and filled it full of fluid and started the car up with the pressure gauge hook, the tranny and pressure was back to normal . The tranny works perfect now. So what I'm trying to say is watch the magnet ,move it away from the filter or epoxy it down.
First i though it was the shift linkage so i tried it again did the same thing, So i put it in second gear and kick it down , the rpm climbed to a round 2500 rpm and went to neutral, let out of the gas and went in gear hard, all the other gears work fine to, Then i started to hear a whining noise, thinking Im losing the pump. I drove it home and hooked up my pressure gauge to the pressure port and the pressure was low around 100psi in all gears even with the vacuum modulator unhooked. So I dropped the pan every thing looked clean , no burnt smell or debre in the pan , I dropped the valve body and check the gaskets and the servo piston, I cleaned every thing and install new valve body gaskets. I looked in the pan before i cleaning it up and noticed the magnet was not were it supposed to be ,I took the new filter and placed it in the pan over the marks left from the old filter and ,WOLA ,, The magnet had slid in the pan under the pickup opening in the filter, Whats the odd of that. I moved the magnet to the back side of the pan and put it all back together and filled it full of fluid and started the car up with the pressure gauge hook, the tranny and pressure was back to normal . The tranny works perfect now. So what I'm trying to say is watch the magnet ,move it away from the filter or epoxy it down. 
06-30-2009, 06:27 AM
#2
great, something else to worry about, lol
which filter where you using, the old one or the later one-i thought the later one with the 4 **** has a smaller opening, would def be a problem-im gonna service mine tomorrow, make some passes fri., def gonna ck the mag. location
now i wonder if when i had the man. v/b in, that could have been one prob., since the plate made it tighter to the pan
which filter where you using, the old one or the later one-i thought the later one with the 4 **** has a smaller opening, would def be a problem-im gonna service mine tomorrow, make some passes fri., def gonna ck the mag. location
now i wonder if when i had the man. v/b in, that could have been one prob., since the plate made it tighter to the pan
06-30-2009, 08:26 PM
#3
I haft to use the old style filter in the new style trans., because of the MVB spacer plates. The new style filter with the four **** , would not let the pan seat to the trans, it need about a 1/8" .I used a rubber mallet to dent the pan outward a round the pickup area so the old style filter would not suck to the pan. I left a round 3/16" gap, so the fluid to flow to the filter with out restriction, If i had not done that. The magnet would have stop the fluid completely to the filter. From what i can tell, There was just enough fluid getting to the filter to engage the clutch pack.
Last edited by Randy WS6; 06-30-2009 at 08:33 PM.
07-01-2009, 07:28 AM
#4
when i had the MVB, i used the newer filter, but tapped the 4 places downward for the filter "****"-now that i think of it, that would have actually moved the filter closer to the pan, that could have been a problem-i had an older filter, but didnt use it-i though they had an inset area in the filter since it was close to the pan, i guess the later filter had more open area all around it
