4L60E Leak question
Thread Starter
Teching In
Joined: Aug 2023
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4L60E Leak question Hello,
I have a 4l60E I swapped into my Land Cruiser paired with a 2000 Tahoe 5.3. After install I took the truck to a reputable transmission repair shop to get there opinion on the install and to generally check it out and they said the install looked good, it shifted great and had no codes to address. After a week of driving around town it developed a leak. I parked it and had it towed back to the same shop and it's potentially a torque converter or pump, they said. They have to pull the transmission to know. It never sounded bad, never shifted bad and never slipped. The leak was substantial. I drove it to work and the went back out to drive it and there was about a half quart of fluid on the ground and dripping off the passenger side on to the drive shaft, 4WD front shaft.
Before I took it to the shop initially I told the tech I had put new fluid in (this is a rebuilt trans from Monster Transmission), and that before I could get all the fluid in (according to the specifications) it measured over full. I checked it according to the specs, warmed up, at idle, level surface. I also asked him to check the flex plate to torque converter spacing.
My question, what could cause a huge leak like that but yet not seem to affect function of the trans as to shifting and operation. I'm going to pull it today.
I have a 4l60E I swapped into my Land Cruiser paired with a 2000 Tahoe 5.3. After install I took the truck to a reputable transmission repair shop to get there opinion on the install and to generally check it out and they said the install looked good, it shifted great and had no codes to address. After a week of driving around town it developed a leak. I parked it and had it towed back to the same shop and it's potentially a torque converter or pump, they said. They have to pull the transmission to know. It never sounded bad, never shifted bad and never slipped. The leak was substantial. I drove it to work and the went back out to drive it and there was about a half quart of fluid on the ground and dripping off the passenger side on to the drive shaft, 4WD front shaft.
Before I took it to the shop initially I told the tech I had put new fluid in (this is a rebuilt trans from Monster Transmission), and that before I could get all the fluid in (according to the specifications) it measured over full. I checked it according to the specs, warmed up, at idle, level surface. I also asked him to check the flex plate to torque converter spacing.
My question, what could cause a huge leak like that but yet not seem to affect function of the trans as to shifting and operation. I'm going to pull it today.
TECH Apprentice
Joined: Aug 2018
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I'm surprised they couldn't pinpoint the leak. It would be pretty obvious if it's from the pump main seal, looking through the torque converter inspection hole. That would require removal of course of the entire unit.
But it could also be cooler lines, shift shaft seal seal, test port plug, pan, rear tailshaft seal, maybe even case connector leaking. These should be able to get corrected without removal of the entire unit though.
But it could also be cooler lines, shift shaft seal seal, test port plug, pan, rear tailshaft seal, maybe even case connector leaking. These should be able to get corrected without removal of the entire unit though.
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TECH Apprentice
Joined: Aug 2018
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It could only be the main seal where the torque converter hub rides/fits into. Maybe the pump-to-case gasket (there are various fluid passages between that one) or seal?
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Thread Starter
Teching In
Joined: Aug 2023
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After removing the starter, and the plastic cover that goes around the starter I got a good look inside the bell housing and can see the flex plate and torque converter. Everything in there is bone dry. I rubbed the lower portions of the bell housing (most lowest points and other spots) with tissue paper, no visible fluid. That combined with the fact that it ran and shifted perfectly makes me think the leak is not from anywhere in that area, not the torque converter, not the pump and not the seal. All the fluid was concentrated on the passenger side. I'm thinking I should not at this time pull the transmission. I also removed the two coolant lines that I had bend into shape that run right by this area, thinking maybe there was a pin hole in one of them and it was spraying up onto the starter area. I pressure tested both these lines and they are solid and have no visible holes. The vent tube is not the source, the dip stick tube is not the source. I'm baffled. Does anyone have a similar experience?
Thread Starter
Teching In
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Hi strutaeng,
There's no fluid in the bell housing. I removed the starter and wiped everywhere I could with tissue paper and see no red fluid, no fluid period on the casting or the flex plate or torque converter. If it was a torque converter hub weld or seal, wouldn't I have fluid pooling in the bell housing?
There's no fluid in the bell housing. I removed the starter and wiped everywhere I could with tissue paper and see no red fluid, no fluid period on the casting or the flex plate or torque converter. If it was a torque converter hub weld or seal, wouldn't I have fluid pooling in the bell housing?
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Yeah, it doesn't seem like it's leaking from the front pump seal or pump itself then.
I don't have any other ideas from your description, other than the leak must only occur when it's under pressure. Even a pinhole leak under pressure creates a strong stream. What type of cooler lines do you have? Are they like AN style?
Maybe put some UV dye and go for a spin to see if you can pinpoint the leak. Or maybe stick a GoPro down there and drive to see if you can find the leak.
I don't have any other ideas from your description, other than the leak must only occur when it's under pressure. Even a pinhole leak under pressure creates a strong stream. What type of cooler lines do you have? Are they like AN style?
Maybe put some UV dye and go for a spin to see if you can pinpoint the leak. Or maybe stick a GoPro down there and drive to see if you can find the leak.
Thread Starter
Teching In
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I removed the starter and got a good look into the bell housing. swabbed it with white tissue paper everywhere I could especially all low points in the bell hosing. That whole area is bone dry, the flex plate, the torque converter. I pressure tested my hard cooler lines.
So I decided to drive it until I could detect the leak. I kept driving a short distance, then inspect, a little farther inspect, faster longer inspect. Ultimately driving it all weekend and no leaks. Fluid level is spot on, transmission is shifting smooth and sound good.
I'm baffled.
So I decided to drive it until I could detect the leak. I kept driving a short distance, then inspect, a little farther inspect, faster longer inspect. Ultimately driving it all weekend and no leaks. Fluid level is spot on, transmission is shifting smooth and sound good.
I'm baffled.
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Maybe it was overfilled initially then?
Was the dipstick calibrated? Is this an aftermarket dipstick? The full line should be at the top of the pan rail. With the pan removed and dipstick installed you can verify. Make a new mark with a scratch awl if necessary.
Was the dipstick calibrated? Is this an aftermarket dipstick? The full line should be at the top of the pan rail. With the pan removed and dipstick installed you can verify. Make a new mark with a scratch awl if necessary.
Thread Starter
Teching In
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That sounds like a good idea. I bought the "OEM" dipstick from the place that sold me the remanufactured transmission. I did do somewhat of a test to see where it was coming in a it indicated full at the pan line. Initially it did have too much fluid. I drained a quart out and rechecked according to the procedure I'm supposed to use. Even if it was overfilled, how many placed could it possibly come out? It didn't come out of the vent tube and it didn't originate anywhere in the bell housing. I pressure tested my hard lines, inspected all my AN fitting connections. It's not leaking now. I guess I won't worry about it now.