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Discussion Starter · #1 ·
83 GMC Sierra 6.2 diesel 4wd Automatic Trans

Not shifting between gears. Seemed like it happened all at once. 3,2 and 1 work if I shift manually but I can't get 4th. In D it only seems to be in 1st. The fluid was a little low but not off the dipstick. I added a quart and this didn't have any effect. I checked the cable and gear (I forgot the name) under the pressfit cap on the side of the trans. Both seemed ok. Could this be vacuum related or something else simple or am I looking at a new/rebuilt trany?
 

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check the vacuum line going to the tranny. could be the cause of your problem.
 

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R.I.P. Sam
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there is no vacuum on 700r, its all controlled by the cable.
 

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check your governor, they can come apart or debris can lodge in the valve cause it to stick. its at the rear of the trans on the left side under a round bubble looking steel cover. clean it real good and make sure the teeth on the gear arent chewed off.
 

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R.I.P. Sam
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so are the other shifts bad if you leave it in drive and not shift manually?

no 4th usually means the 2nd gear is shot as 4th is an extention of 2nd. usually seen as not wanting to shift out of 2nd, and time for a rebuild
 

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Discussion Starter · #7 ·
In D I cannot go more than 20 mph without the rpms topping out. It seems like im in 1st but maybe this is 2nd? On an open road I can sometimes get it going fast enought to somehow get into what seems to be 3rd when i have the indicator in 3 and get it going about 45 to max 55. Is rebuilding the trans something I can do myself with reasonable mechanical ability. I replaced clutches in 4wd before but never rebuilt a trans. Also can anyone recomend resources for parts and manuals.. thanks
 

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Rebuilding a 700R4 is advanced auto mechanics and this transmission does not tolerate sloppiness. That said, you have nothing to loose except time and you will gain a lot of knowledge if you attempt it. At the least you will see how they work. And you can always get a newer one from a junk yard if needed and you don't want to buy a rebuilt one.

Here is a web page that goes into detail on the rebuilding process of the 700R4.

http://syty.huryde.com/OLD/html/trans/Tranny Rebuild.pdf

If you do decide to rebuild it, get a GM "Light Duty Truck Unit Repair Manual" for the year of your transmission. A good alternate is the ATSG manual for the early or late transmission(82-86 or 87-1/2 -93).
 

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and ensure a CLEAN and STERILE environment in which to clean the transmission, the slightest bit of dirt in a transmission is a bad thing. you MAY require special press tools to get at snap rings, though I have not rebuilt one personally so i can not be sure.
 

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blueburby is correct about cleanliness although I was talking to a transmission technician at a GM dealership several years ago. He was rebuilding a transmission on his bench (Outside under a shade here in Phoenix with our dust storms). When Mesa Community College had classes on automatic transmissions, they had dedicated, air conditioned room, which even included a parts cleaner just for valve bodies (the most critical transmission part). In practice, I rebuild in my garage on a work bench. When I am not working on the transmission, I cover all the parts with a sheet.

One very important thing about the case surface where the valve body attaches. I use an 8 inch, very flat, fine carborundum stone to insure flatness on this face. You will find that in the areas where the bolt holes are located, the surface may be distorted up, many times due to someone over torquing the bolts (or NOT using a torque wrench). Be careful, you want to just remove the high spots which will prevent cross over leaks.

The Web site article I referenced does give excellent suggestions for making a lot of the tools you will need. Some of the tools that I invented are shown in the article - I should have read it first! The only problem with this article is that it is not complete. The last part on assembly is missing.
 
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