4l60e Still Not Right After Rebuild - HELP PLEASE!!

[Steve A]

Check out www.transmissionbench.com, good guy with considerable knowledge

 

[wheelman]

Hey guys,

First post here, but have been reading the forums relentlessly trying to figure out what the hell is going on with my truck. If anyone has any advice, please don't hesitate to share. Thanks in advance.

My truck:
1998 Chevrolet K1500 4WD 5.7l V8 260k miles

About a month ago, I had my stock 4l60e stock transmission rebuilt by a reputable transmission shop in Washington State. The diagnosis was that the 3-4 clutches were shot and the transmission needed a full rebuild. I got my truck back, and pretty much right away, it seemed like it wasn't driving the way a truck with a rebuilt transmission should be driving. I took it to a different shop to get their opinion on it, and they said something was clearly still wrong. They pulled the transmission out of it and said they found an electrical issue that was causing the erratic shifting issues and I got it back a week later. The second shop told me that the rebuild looked good, there was just some minor electrical problem that had been overlooked during the rebuild, and now it was shifting through all the gears properly. Despite that, it still was not driving the way I expected/hoped. Here are some of the symptoms:

1. When cold or after sitting for a while it seems to drive the best/most consistent.
2. Seems to hunt for the proper gear especially between 3/4, erratically shifting between the two even when going a constant speed, leading to really low rpms + lack of power.
3. When accelerating uphill or under load, 1st through 3rd seem to shift mostly smooth, but when shifting from 3rd to 4th, I pretty much lose all acceleration and power right away.
4. When climbing a long steep hill in 4th gear, it will drop out of 4th gear into 3rd, sometimes even 2nd, and rev super high (yesterday, revved so high, blew a coolant line, spewing coolant all over my engine)
5. Shifts are mostly smooth, but do feel a slight delay/surge occasionally, and don't always seem to be occurring at the proper time.
6. Very slight shudder at idle.
7. Speedometer is off anywhere from 5-13 mph depending on what speed I'm going (recently replaced VSS on transfer case, so I know it's not this).
8. No CEL whatsoever, which seems kind of odd, not even after blowing my coolant line yesterday...

At this point, I'm convinced it has to be some sort of electrical issue, with the transmission not receiving the proper power or signals at the right time. In doing my research, I've found a few common issues, one of them being the ignition switch on the side of the steering column. I guess a lot of the wires that run power to the transmission run through that harness, and is a common failure point on these trucks. I've even read something like a faulty brake light switch can cause transmission problems as well. Maybe a bad PCM/ECU. I'm lost at this point.

If anyone has any advice about what might be the possible culprit, or need any other information to help determine what the issue might be, please reach out.

Thanks again,
Sam

 

[wheelman]

I can't believe you guys. Why do you all go. To rebuild shops. Every one gets lied too and cheated. Now your trans is still screwed and broken. You can't get your money back. I can tell you what is wrong. But you should of found a Chevy dealer with there own trans man. You would have a nationwide warranty and 36,000 miles. The OK listen up. Your sun shield is bad. Cracked stripped. It's what the stock ones do. It holds a clutch pack

Now you got to get it. Taken back out and gone in to. The Chevy guy will use after market parts. Not stock crap. He will use the beast sunshield. And what ever else that is bad in it.

I had mind done a few years ago. Eight hundred dollars. The ml60E. All have this gearing problem. Stock trans parts are no good. Now find the right trans guy and repay. If the ones you used. Knew what they were doing

You would not have a broken trans.

 

[evilunclegrimace]

If you go to a GM dealer and have a trany rebuilt you MIGHT find one that will rebuild it with after market parts but GM WILL NOT offer a 3 year 36,000 miles warranty on non factory parts.

 

[Hotrod69ss]

I'm not sure if this applies to a 98 model year truck or not, but I had similar troubles with my 96 when I had the trans rebuilt, actually when shifting into 3rd one day from 4th it gave out entirely. Turns out theres a service bulletin for my year truck (again, not sure it applies to a 98) but the bulletin is right from GM and just supplies a ground wire that must be added to the engine computer that boosts line pressure for 2nd, 3rd and 4th gear through the trans so you don't have all the same problems and eventually end up losing the tranny again

 

[Hotrod69ss]

I'm not sure if this applies to a 98 model year truck or not, but I had similar troubles with my 96 when I had the trans rebuilt, actually when shifting into 3rd one day from 4th it gave out entirely. Turns out theres a service bulletin for my year truck (again, not sure it applies to a 98) but the bulletin is right from GM and just supplies a ground wire that must be added to the engine computer that boosts line pressure for 2nd, 3rd and 4th gear through the trans so you don't have all the same problems and eventually end up losing the tranny again