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4 Rebuilds Later, Problem Diagnosed

638 Views 4 Replies 4 Participants Last post by  kilr95ss
After the last time the 4L60E broke, I let it sit for almost a year, got a R1 not long before the tranny crapped out, faster and cheaper, no rush to get it rebuilt.

Well, a couple weeks ago I finally decided to pull the tranny and get it fixed. I noticed the fluid looked a little weird but didnt think much about it. The builder called me and said it was ready, said it had water all in the tranny. The most likely place that water could have gotten in there would be the internal oil cooler, probably has a leak in one of the plates. I guess letting the car sit that long, it let the water fill the tranny were as while it was still working, just enough water got into the tranny to foul the guts.

The radiator came from the plant where I work, we build heat exchangers, oil coolers, radiators and condensers. After telling some of the guys I work with about the leaking internal cooler, one of our QA guys reminded me about the time a few years ago when we had a issue with bad coolers coming from China. Guess I got one that slipped through the system.

Building a custom external cooler and getting rid of both factory coolers. Now got to send my TC to Edge for a cut and clean, hopefully no damage in it.
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It's worth mentioning two things here:
1. Unless the 4L60E gets hot enough to boil out any condensation on a semi-regular basis, it is likely that you may get some water buildup inside the transmission. This is especially true if your 4' vent harness isn't installed. There's a reason GM made it 4' - it's to keep the trans from sucking in moist air every time you get on the gas or the transmission cools down.

2. Coolant will cause the 4L60E's clutch material to delaminate, so you really don't want to let any sort of coolant leaks go. If you see oil in the coolant or a funky look to the transmission fluid, attend to it immediately. And yes, having internal radiator coolers is a good idea, for reasons that have been discussed in other threads.
It's worth mentioning two things here:
1. Unless the 4L60E gets hot enough to boil out any condensation on a semi-regular basis, it is likely that you may get some water buildup inside the transmission. This is especially true if your 4' vent harness isn't installed. There's a reason GM made it 4' - it's to keep the trans from sucking in moist air every time you get on the gas or the transmission cools down.

2. Coolant will cause the 4L60E's clutch material to delaminate, so you really don't want to let any sort of coolant leaks go. If you see oil in the coolant or a funky look to the transmission fluid, attend to it immediately. And yes, having internal radiator coolers is a good idea, for reasons that have been discussed in other threads.

+1 ;)
Didn't know that about the vent tube but from how my builder described it, sucking in moisture from the vent would not have gotten that much water in there. Guess I'll look for another plate cooler for the radiator but for right now, just gonna use the external cooler I made.
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