4L60E puking fluid on the driveway when truck is parked

[JST A 6]

I have a '97 GMC Sierra K1500 Z71 with a 4L60E transmission, and whenever it sits for a while a puddle of transmission fluid appears on the driveway underneath. It never happens while I'm around (I never actually see it drip) but it leaks pretty bad sometimes (one day when I left for work in the morning it had a 5-6" diameter puddle under it, and when I came back home it was at least triple that size). I have not been able to pinpoint where it is coming from, but I have felt around the servo, the dipstick tube, and the electrical connector on the passenger side where the puddle generally tends to form under it and everything felt dry. A friend suggested that maybe it was coming frrom the vent on top of the transmission, but what would cause fluid to come from the vent when the truck hasn't even been driven for days? Right now the truck is sitting at my mother's house until I get a major fuel leak repaired, at which time I may just get rid of it. It's been there since Mother's Day when I went to visit her (been too disgusted to look at, let alone fix my truck especially since the gas tank is full and needs to be dropped to do the repair). There is now a 2-3 foot diameter puddle of transmission fluid under it. Any ideas as to what could be causing this loss of fluid? Thanks in advance...

 

[forcefed3.8's]

Tailshaft seal?

 

[JST A 6]

I should probably add that it was a freshly built transmission just over half a year ago, and is in my DD truck with a 305 V8 so it has not had a hard life. It was installed in November of '08. The guy that built it and installed it said he would take care of me if I had any problems but he's over 200 miles away, so I'm hoping this could be something simple that I could handle...

 

[JST A 6]

Tailshaft seal?

No, the leak is not that far back. It's right up by where the pan is.

 

[JST A 6]

Here's a few things that were done to this transmission while it was being built--new torque convertor, all new solenoids, heavy duty "Beast" sunshell, Z-pack (14 clutches for 3rd & 4th gear vs. stock 5 or 6 clutches), Corvette servo, and a deep pan with a drain plug. Stock transmission fluid cooler in the radiator was bypassed and in its place a fairly large external cooler was installed. Don't know if any of this would make a difference or cause my problem but figured I'd list it here just in case.

 

[SSedan64]

When it sits for a while the fluid from the converter will drain back into pan and raise the fluid level above normal operating/checking level. The electrical connector seal may be bad. I've heard that trans has a problem with the seal and something inside the connector cracking and causing a leak.

 

[Chuck Leeper]

Considerable "reading material" here..
4L60E oil leak - Google Search

 

[Steve V]

I would look at the pump area,there's a gasket,O ring,seal/bushing,selector shaft seal would also be up front. If it's not the pan,dip stick,cooler lines or extension housing O ring(both 2wd and 4wd have this) or tailshaft seal.

You can add dye and then trace it with a light.

 

[steve hughes]

Spray foot powder on the trans to track the leak.

 

[GNeric]

I have seen HUNDREDS of transmissions that were just built and the shift shaft seal never got changed. Either the builders don't like to pull them or just plain forget. If the shaft has a wear area where the seal lip rides and the new one was put back in the same spot, it can leak. New seals are cheap. I keep at least 40 on hand to make sure if someone can't find one, I can help.

 

[gsgns4me]

For the fuel tank issue, it's generally easier to remove the truck bed than it is to drop the fuel tank.

 

[injdinjn]

Remove the flywheel cover and check the front of the pump. Probably dry above the shaft and wet below, which means the pump shaft seals are leaking.

 

[JST A 6]

I have seen HUNDREDS of transmissions that were just built and the shift shaft seal never got changed. Either the builders don't like to pull them or just plain forget. If the shaft has a wear area where the seal lip rides and the new one was put back in the same spot, it can leak. New seals are cheap. I keep at least 40 on hand to make sure if someone can't find one, I can help.

I am sort of suspecting that shaft seal since I did see some fluid in that area today. May be onto something here, but on the other hand it may not matter as I might be trading the truck in tomorrow.

For the fuel tank issue, it's generally easier to remove the truck bed than it is to drop the fuel tank.

I had given this some serious consideration but the mounting bolts for the bed were a heck of a lot more rusty than the gas tank strap bolts, and you're talking who knows how many bolts for the bed vs. 2 bolts for the tank. At any rate, I got it done today by siphoning all 34 gallons out of the tank, dropping it, and putting a little bit of the gas back when I was done (I didn't want to be giving it to the dealer if I trade the truck in tomorrow so I put the rest of the gas in my sister's car).

Thanks to all for the help with the transmission issue; hopefully after tomorrow I won't be needing it.:biggrin:

 

[Roc87]

I had a leak in the 700 in the elky. Wouldn't leak for a day or two, then all of a sudden it would dump a quart or two! Replaced nearly all gaskets including the shift shaft seal and it turned out to be the dipstick tube seal.

 

[JST A 6]

I had a leak in the 700 in the elky. Wouldn't leak for a day or two, then all of a sudden it would dump a quart or two! Replaced nearly all gaskets including the shift shaft seal and it turned out to be the dipstick tube seal.

Sounds a lot like the symptoms I had. It dumped probably at least half a quart of fluid in my mother's driveway before I got the fuel leak fixed and brought it home, and I had to add probably about half a gallon to bring the level back up (it had been leaking for some time on & off before I had taken it to my mother's house). I had the truck about another 3-4 days after that, and never saw a drop of fresh fluid on the driveway during that time. I have since traded it on a MUCH nicer truck so it's somebody else's problem now. There's still rusty fuel lines, brake lines, power steering lines, and oil & trans cooler lines plus a lot of other rust under the old truck, and the steering was starting to get quite loose so it was just time for it to go. Here's my new (used) truck--just what I needed was another black vehicle! The 4th picture is the fuel tank sending unit from the other truck. The 3rd line from the left broke off completely towards the end where the hose was connected to it and was the one that had been gushing fuel when the pump ran. Gives you an idea of what the rest of the truck was looking like underneath.

 

[SSedan64]

Don't you just love road salt.

 

[JST A 6]

Don't you just love road salt.

Yup, same thing happened to my dad's '99 Ford F250 only it was a brake line. He lived here in northern Ohio until about 4 years ago, then moved down to Tennessee. By that time it was too late; the salt had already taken its toll on his brake lines. I went down to visit him once and we were riding downhill in his truck into the valley behind his house to the little camping/party spot he has. As always he was riding the brake all the way down the hill, and suddenly the pedal just went to the floor and the truck started picking up speed. He had to veer off the path into a tree to get the truck stopped. Of course his insurance wouldn't cover any damages because they said he was offroading, plus with it being his truck on his property there was no police report.