Reverse will not engage after changing transmission fluid and filter. Any ideas?

This is in regard to a Chevrolet Silverado 1500 with the 4.8L engine, 2WD, automatic.
It has 209287 miles on it.

I have owned this truck since February, however it has spent the past 3 months in my front yard with the front end raised up on spare rims so that I could work on it. During this time, I did a number of repairs and preventative maintenance, including replacing the transmission fluid and filter. I replaced the actual transmission pan itself, too, because the drain plug was completely rounded.

When I removed the transmission pan and drained the fluid, it did not look burned or dirty, however the filter had never been changed based on the date code, and how dirty it was. Also, I got out more than 2 gallons of transmission fluid, however adding only 5 quarts (the recommended amount for a drain-and-fill) was enough to make the dipstick read “full: cold” with the engine idling in “P”.

Today, I lowered the front of the truck down onto the ground, with the intention of going to buy new tires. Unfortunately, it will not engage in reverse, even though it did before I worked on it. I remember having to slightly bend the bracket which holds the shift cable in order to get the pan off, in addition to taking the exhaust pipe apart, however I bent the bracket back to what it should be.

I have looked online for information about this problem, and people talk about a “sun shell” in the transmission that can break, but I can’t imagine that this would have happened while the truck was parked in front of my house, not being driven.

Any ideas, besides taking it to a transmission shop, most of whom only want to sell a whole new transmission?

if you drained “More than 2 gallons” and only put in 1.25 gallons, I’d say you need to ad more.



If there were no solid pieces in the pan, and just the typical buildup of fine metal powder on the magnet, what is the most probable explanation, and can this be fixed without paying for a new transmission? Is it likely that overfilling the transmission had somehow masked the real problem?

If the trans fluid was at the proper level before and you drained out 8 qts it can’t be full with only 5 qts.

Does it move forward in D, or any other position including N? It’s hard to get that shift cable bracket back to normal if you bend it to take off the pan. I assume you checked to see if it goes backwards in N.

Are you 100% sure you have the filter pushed all the way up into the grommet?

If I remember correctly, a broken sun shell on that trans will give you no R and a second gear start when in D. What does it do with the shifter in D?

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It moves forward in “D”, “3”, “2”, “1”. In “R” or “N”, it acts like it’s in neutral. I don’t have enough space in my fenced-in yard to go forward enough to see which gear it’s starting out in.

Also, I think the transmission was overfilled before. The transmission cooler fitting on the radiator was leaking a lot, and the transmission pan gasket was leaking too. It may have been run low on transmission fluid in the past, but I have no knowledge of that.

I was not able to remove the round metal gasket which the filter mates with. After scratching it up with a screwdriver in an effort to remove it, I gave up and reused it.

Oh. Overfilling a trans by a couple of quarts can create some problems and also may mask others.

Google a picture of 4L60 reaction shell and you can see how the shell can crack but not come apart and even if it did pieces may not make it to the bottom of the pan. Since it was full before I might try overfilling it again, just for fun.

If I had the truck I would run it on the hoist with a scan tool and watch the gear changes, or just run it and count the shifts. But it sounds like you’re going to have to drive it on the street. If the shell is in fact broken you should have no R and only 2 and 3 going forward.

Are you 100% sure the filter is up in the trans all the way? Did you change the bushing for the filter neck?

No. I could not get it out. I scratched it as well, trying to remove it, but ultimately gave up and reused it. The filter is definitely installed correctly. It clicks into place. At this point, I am not sure if I should put back as much transmission fluid as I took out (which will overfill it a lot) or if there’s something else I can check, or if I just need to take the truck to a transmission shop.

I went outside now that the sun is mostly down and tried it again. I noticed that each time I shifted from “P” to “R” the truck would creep backward several feet, but then act like it’s in neutral. I checked the dipstick again, with the engine idling in Park, and it was dry. I added the remaining 3 quarts of Dexron III, which brought it up to the “full cold” position, and after that, reverse worked fine!

I guess it just took a long time for the fluid level on the dipstick to drain down after lowering the front of the truck, and the instructions in the Haynes book to add 5 quarts for a drain-and-fill are wrong. It really takes 2 gallons.

There are no specs for refilling a trans after a pan drop. If I pull and replace the pan in 15 minutes I will lose far less fluid than if it sits and drips overnight or for 3 months.

Glad it works now. Yes, it often takes several minutes for the fluid to finish running down the dipstick tube to get a proper reading.

The proper method is to remove the shift cable from the bracket, then remove the bracket itself. I believe you need a T40 socket to remove the bracket bolts

I realize you’ve already fixed the problem, but you might want to file away my advice for the next time you have to remove the pan

As for this new pan . . . does it come with a drain plug?

I’m not sure if you’re aware of this is, or even care, for that matter . . . but very few 4L-60E pans came equipped from the factory with a drain plug. Those pans with the factory drain plug are a rarity and almost worth their weight in gold. It sure makes a trans service easier :+1:

If it were my truck, I would have fought tooth and nail to remove the rounded plug without damaging the pan in the process. I have seen a few guys irreparably damage transmission pans trying to remove drain plugs :laughing: And it’s usually been because they were using the wrong methods and/or their tools weren’t up to the task

Yes, it does. I don’t want to go through the hassle of removing the pan for the next routine fluid change.

This was definitely the original pan, and the drain plug is recessed, which means that you won’t get out all the ATF. The aftermarket pan has the drain plug in a different location, and it’s not recessed.

I think the truck is running properly, and I took it for a test-drive to a gas station, and then to do some grocery shopping. I noticed that when trying to accelerate from a dead stop, the tachometer goes up to 1500 RPMs before the vehicle moves, unsure if this is some slight slippage, or normal for this model. I might take this to the transmission shop which the company I work for uses, to have it checked out.

As for the original drain plug being recessed . . .

I believe that was to protect the drain plug from being damaged or torn off

Doesn’t sound normal to me :neutral_face:

It would not surprise me if a 200k mile trans had issues.maybe the seller did a drain/fill and sold it?

I drove the truck again today. The transmission definitely upshifts 4 times in “D”, however it has barely any torque until the speed has gotten up to 11-15 mph when it shifts up to 2nd gear. Also, when it does upshift, I need to release the accelerator to avoid sudden rapid acceleration.

Interestingly, if I shift the transmission into “1” while stopped, it has normal starting torque in 1st gear, and if I then shift to “D” while already moving, it works fine. I think this is a computer/sensor problem, and will be making an appointment to leave this at a transmission shop to see what they think.

I believe manually selecting first gear increases the line pressure to the clutches, that may be why you are getting better performance in first gear.

If you damaged the filter tube seal in the transmission the pump will draw air, you will experience weak engagement problems and foaming of the fluid.

I finally had a chance to take the truck to a professional transmission shop. The problem was that some of the shift solenoids got damaged somehow. They replaced the solenoids, and the transmission is working properly now, with the transmission fluid at the proper level. It was not very expensive.


I’m quite familiar with this particular transmission

As such, I have a few ideas

In some applications, where a 4L60E is used, it is a ____ to remove the pan
I believe in this particular application, “the book” calls for lowering the exhaust. If you don’t do this, it’s rolling the dice. Sometimes you simply can’t remove the pan at all. Other times, you can remove the pan, but BARELY and only by scraping the the valve body. And I mean REALLY scraping the valve body. And there’s all sorts of solenoids and connectors that come into contact with the pan, when you’re removing it . . . if you chose not to lower the exhaust

As such, I can envision damaging a solenoid and/or connector during a trans service . . . on this particular application

Please don’t take all of this the wrong way

I’m not implying you did anything wrong

I’m just saying I have an idea of how it could happen . . . based on professional experience on this exact truck and this exact automatic transmission. We have tons of them in our fleet.

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