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Gary, Chevy Technician
Category: Chevy
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Experience:  15 years GM master tech
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1999 K1500 Suburban 5.7, 4L60E: transmission shifted fine,

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1999 K1500 Suburban 5.7, 4L60E: transmission shifted fine, then lost 3rd and up. Seems to start in 2nd, but will manually shift into 1st. 3rd shift causes engine runaway. Changed oil and filter, and installed transgo shift kit, no improvement, however I did find a small pin in the waste oil drain pan...I did not see it until after I pulled the drain pan from under the truck, since I am working off of jack stands. The old oil had a slight odor, but as I mentioned, the truck was fine then next trip problem occurred. No codes.
so no matter what gear you shift it into when its supposed to be in 3 rd gear or shift to 3rd gear it will rev up and not move like 3rd in neutral ?and you changed the fluid and filter and installed shift kit to correct the 3rd gear problem?
Customer: replied 4 years ago.
Yes, that is correct. Shift lever in OD truck will move off in what I believe is second, reach speed to shift and then act like in neutral. I can force down shift with gear lever. If I manually start in 1st from stop, it will move off as normal, move shift to 2nd acts normal, move shift lever to 3rd acts like in neutral.
ok what is wrong is the 3/4 clutches inside the transmission have failed.this is a very common problem for these transmissions.since you have 1 st and 2nd it shows the shift solenoids and computer control to shift it are fine.that transmission needs to come out and aprt to be rebuilt or replaced.
Customer: replied 4 years ago.
So, you are suggesting that the 3-4 failure comes on in an instant? Also, any idea what the pin might be, it's 3/16 x 3/4 with slightly rounded ends?
not off the top of my head i do not know about that pin.usually a pin like you are desribing could be a roll pin for the valve body.but if you had a valve body problem usually it would effect 2 gears and not just 3rd gear.those 3/4 clutches can go in one shot the 3/4 clutch piston could have failed but the only difference inside that transmission from 2 to 3 rd gear is the 3/4 clutches so when 3rd acts like neatral there is something wrong internally with the 3/4 clutches
Gary and 4 other Chevy Specialists are ready to help you
Customer: replied 4 years ago.
Thanks for your input. I am still wondering about the pin.
they will find where it went too when its apart
Customer: replied 4 years ago.

It is going to be me doing the work, being an old yankee I subscribe to the famous words of wisdom "I don't care how much more it is going to cost or how much longer it going to take, I am doing it myself."


I will stop by a local transmission shop to see if they recognize the part.





ok let me know how you make out

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