4L85E Front Seal Leak

[L31MaxExpress]

Just drained the fluid and about to tear into the no upshift transmission.

 

[L31MaxExpress]

About to put the pan back on, fill it up and roll the dice. 2-3 shift valve felt stuck initially, took a good bit of effort to pry it forward and then it felt sticky. Sprayed some carb cleaner in its bore a couple of times and kept working it and it feels as smooth as the 1-2 shift valve now. Plenty of stiffness to the springs and both return with a solid click when I released the pick with them under tension. New Rostra shift solenoids and internal harness installed from my local Transtar as well. Fingers crossed because I really do not want to remove the valve body laying on my back. Will be ready to test it out in about an hour or so. I also verified the fluid level of the stock stick. It is WAY off from the recomeended +1/4" above the pan rail. New full mark will be a solid 2/3" above the factory fill line.

 

[L31MaxExpress]

Has all 4 forward gears again. I think it was definitely the shift valve that was stuck. The internal harness was seeping a bit through the terminals so I am glad I changed it.

Also forgot to mention, ran a line pressure test before I tore into it and it was spot on. TCC was working great as well. I left the EPC and TCC solenoids untouched. Unit has some age but it only has 85K miles on it.

 

[L31MaxExpress]

I will touch back on the unit in the 97 van now that I have had some time to get the proper yoke engagement via a longer driveshaft and have tamed it a bit in the tuning. I put the Superior shift kit in it and because I had already drilled the line to lube modification, I ommited the revised regulator valve setup. I used the larger boost valve and the higher pressure spring. I also put the white spring they call out for HD use on the accumulator control valve. Drilled the feed holes for the RV/Heavy duty towing size recomendations. That was a mistake. Ended up having to zero out the added pressure in the upshift pressure adder tables to get it to shift somewhat normally at lighter throttle. Even with the stock 6.0L van line pressure and torque management settings I was running it became a fairly beefy shift at heavier throttle. I would actually say even harsh. I pulled a bit of base line pressure out of it to smooth it out some and it still barks 1-2 at heavier throttle. Speedometer literally jumped 10 mph shifting 1-2 at 50 mph at WOT from the tire spin, it was definitely a weird feeling breaking tires loose at 50 mph in a 7,000 lbs van. Just word of advice for anyone doing this, I would highly suggest the smaller feed hole recomendations or something less than the HD recomendations especially if you intend to drive it on the stock tuning.

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[NickTransmissions]

Now you (and anyone else who reads my 4L80 posts) know why I never use shift kits with that transmission. They're totally unnecessary.

That calibration is what I like for 2800-3200 stall street strip applications with dual-fed direct clutch. The factory PR valve spring is fine, hp springs arent necessary. Id buy a Transgo 4L80E plate and drill the 2-3 and maybe the 3-4 to modest sizes.

If you leave it like it is now, you may or may not start to break stuff inside the case...

 

[L31MaxExpress]

Now you (and anyone else who reads my 4L80 posts) know why I never use shift kits with that transmission. They're totally unnecessary.

That calibration is what I like for 2800-3200 stall street strip applications with dual-fed direct clutch. The factory PR valve spring is fine, hp springs arent necessary. Id buy a Transgo 4L80E plate and drill the 2-3 and maybe the 3-4 to modest sizes.

If you leave it like it is now, you may or may not start to break stuff inside the case...

@NickTransmissions speaking of which are TH400 and 4L80E fluid pumps just noisy in general? I have not owned many and I cannot remember if they all had this sound working on them years ago. Most of the TH400 and 4L80E stuff I worked on was older oil field and construction trucks and almost all of them had cracked and leaky exhaust manifolds so I do not remember hearing much other than the leaky exhausts. All 3 units that I currently own have kind of a rattling sound in what seems to be the pumps. Think of those old metal slinkies when you shook them back and forth and the metal pieces hit each other. Kind of all sound like that too. I just had the pump apart in the unit that is in my 97 as you know. Clearences were spot on and everything visually looked like new there. All 3 units, 2 4L80/5Es and 1 TH400 have this kind of slinky, rattling sound in both Park and in Gear. So it is not part of the gear train.

 

[NickTransmissions]

@NickTransmissions speaking of which are TH400 and 4L80E fluid pumps just noisy in general? I have not owned many and I cannot remember if they all had this sound working on them years ago. Most of the TH400 and 4L80E stuff I worked on was older oil field and construction trucks and almost all of them had cracked and leaky exhaust manifolds so I do not remember hearing much other than the leaky exhausts. All 3 units that I currently own have kind of a rattling sound in what seems to be the pumps. Think of those old metal slinkies when you shook them back and forth and the metal pieces hit each other. Kind of all sound like that too. I just had the pump apart in the unit that is in my 97 as you know. Clearances were spot on and everything visually looked like new there. All 3 units, 2 4L80/5Es and 1 TH400 have this kind of slinky, rattling sound in both Park and in Gear. So it is not part of the gear train.

While I hardly ever drive in the vehicles for which I do transmissions and don't own a 4L80E-equipped vehicle (yet), I do not know them to be particularly noisy. I know the TH475s have noisy gears but the few times I have been in 4L80E vehicles for which I built the trans or prior to the rebuild doing diagnosis w/scan tools, I have not noticed them to have noisy pumps.

Wonder if it's something in the vicinity of the transmission but not the transmission itself. Maybe exhaust related components or loose converter covers...