Rapid death of a new 4l60e
Thread Starter
Staging Lane
Joined: Sep 2004
Posts: 99
Likes: 0
From: Fargo, ND
Rapid death of a new 4l60e I recently had my 4l60e rebuilt when I had my SY 3500 installed. I had a shift kit and some better clutch packs installed, along with a hardened input shaft. Well, I set out on a highway trip, and about 4 hours into it, I lost third. 
Upon closer inspection, there was transmission fluid all over the bottom of the car, and the PCM was commanding the 2-3 shift, but the car misses and goes into neutral. The guy at the GM dealer thinks the Super Yank isn't locking up, causing it to overheat the transmission fluid and frying the clutch packs. Any advice?
Upon closer inspection, there was transmission fluid all over the bottom of the car, and the PCM was commanding the 2-3 shift, but the car misses and goes into neutral. The guy at the GM dealer thinks the Super Yank isn't locking up, causing it to overheat the transmission fluid and frying the clutch packs. Any advice? 
TECH Regular
Joined: Oct 2002
Posts: 465
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From: Edgewood, MD
I would trust a GM dealer with anything aftermarket, but that's just me. Heck..I don't even trust them with their own parts (especially after they try to tell me that my car has an optispark.)
But anyways...who did the reinstall of the tranny? Was it you? The dealer? Or some other shop? I'd start by finding out where that fluid came from. It wouldn't surprise me if something wasn't tightened down or connected properly, the fluid leaked out, not enough fuid was left in the tranny to properly cool the tranny and keep stuff lubricated, and so stuff started to fail. And 4 hours into sounds about the right time frame for a connection to come loose and dump all your tranny fluid out. I would start questioning whoever did the install, what's their explanation for the fluid being all over the bottom of the car.
Could you feel the convertor lock when you started driving her? (Should almost feel like she's shifting into another gear and your rpm's should drop.) If you noticed that, then their theory of the convertor not locking and overheating is B.S. in your case.
But anyways...who did the reinstall of the tranny? Was it you? The dealer? Or some other shop? I'd start by finding out where that fluid came from. It wouldn't surprise me if something wasn't tightened down or connected properly, the fluid leaked out, not enough fuid was left in the tranny to properly cool the tranny and keep stuff lubricated, and so stuff started to fail. And 4 hours into sounds about the right time frame for a connection to come loose and dump all your tranny fluid out. I would start questioning whoever did the install, what's their explanation for the fluid being all over the bottom of the car.
Could you feel the convertor lock when you started driving her? (Should almost feel like she's shifting into another gear and your rpm's should drop.) If you noticed that, then their theory of the convertor not locking and overheating is B.S. in your case.
Thread Starter
Staging Lane
Joined: Sep 2004
Posts: 99
Likes: 0
From: Fargo, ND
It looked like the fluid came out of the vent tube, but it was enough of a mess to make it difficult to tell. The place that built it for me is probably going to fix it, but I'd like to be able to drive on the highway without burning up my transmission.
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Banned
Joined: Nov 2003
Posts: 246
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From: Pocono Pa
i can tell you from experiance that if the 4l60E convertor doesn't lockup it will over heat the fluid and push it out the vent.After a few miles of boiling fluid pushing out the vent the trans clutches will start to over heat and things will start burning up...the 1st things to burn up are the fluid and clutch packs.Also with the oil overheating and boiling its possible that air is mixed with the oil causing total disaster inside the trans.I've seen transmissions totally fried because the convertor didn't lock on the highway.Short trips you can get away with it...but not running 60+ steady for any length of time....the heat generated from the slip in the convertor is extreme.Also after market convertors maybe designed to slip more....causing even more heat.So i would say its dam good guess it wasn't locking...thing is if you never checked it AND they never checked...you will never know what really happened.I'll bet you'll check when you get it back!...!st thing i do if i go on a long trip with the TA is tap the brake pedal @ 65 mph and watch the tach....better rise up then lock down...if it doesn't i go NOMO.
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Yank has had a problem with their lockups failing, but not normally on a new convertor. Mine failed after 20 months of abuse. Did you put a tranny cooler in? It does sound like an over heat problem.
Thread Starter
Staging Lane
Joined: Sep 2004
Posts: 99
Likes: 0
From: Fargo, ND
The transmission rebuild and Super Yank were both about 2 weeks old at the time, and a transmission cooler was installed, but I think it couldn't handle four hours of converter slippage. Would failure to lock the TCC set an SES light?
