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700r4 random issues

OffRoadOhio

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Lancaster Ohio
I know 700r4 questions have been asked and answered all over the internet. I have been reading thread after thread on many differant sites trying to solve my problem and havent came across a similar issue yet.

Back story. This is my g/f's truck. Shes had it around 7 years. It is your typical old chevy that is pieced togather using many differant trucks, becuase all of the local hilljacks think they know how to fix them. has a 350 thats been in prob 6 differant trucks and is carburated. This truck was a TB truck origianly and was a standard. It now has a 700r4 that is of the older variety as it has no electronics except the lock up TQ. two years ago she took it to a mudbog and the transfercase and adapter literally fell off the transmission and it puked the fluid.

Truck sat until last June when I came into her life and decided to try to fix it for her. Onc ei got the tcase mounted back up and filled the trans with fluid it wouldnt shift from first and it also had a major oil leak in the engine.

We let it sit again until I found time and the money to tear into it. Found the shifting issue was a stuck throttle valve. I took it and govenor out and and cleaned them up and removed the gunk build up and reassembled.

Truck then shifted a little odd so I adjusted the cable some and it started shifting decent but 4th gear didnt seem right.. Then suddenly really late hard shifts like the TV cable was out of adjustment. I tried all sort of adjustments and no matter what it never changed.

I hooked it up to a flush machine and did a full flush on it just to see what would happen. Drove it around with no change.

Put it on jack stands and got under the hood and manually controlled the TV cable while running the throttle by hand aswell. it shifted late and about threw itself off the stands for the first few shifts. Then i seemed to find a sweet spot in and the shifting got smoother, although it was still really late.

I also was trying to diagnose a no reverse light issue at the same time and thats when I noticed that there were NO wires hooked to this 700r4. I dug around in the harness and found the 3 wire plug that plugs into the trans with a badly messed up end on it. Went to the parts store and found a matching end and replaced it and plugged in. Test drive. No change in transmission, on the ground still very hard and very late shifts.

I got mad for the day and parked it. G/f asked if it was good to drive to work the next day 9 about 2 miles) i said yeah just be easy. She got in it and I heard it shift nice and smooth as she drove away. She called once at work and said it worked better than it ever has. She put about 200 miles on it in 3 days with it shifting flawlessly. Then called me last night saying it sback to the hard and late shifts.


What would cuase it to be shifting hard and late one day, then perfect the next, then back to crappy again?
 
Shift kit maybe? All I got. Sticking tv. Someone else on here Jaffa a similar problem and I believe used a aftermarket tv.
 
Most likely a sticking TV valve, pretty common on a 700R4 that has some debris circulating in the system.
 
Either sticking TV or governor. If both were gummed up before and sticking it's quite likely doing it again, or at least not moving completely or smoothly. On mine the governor was stuck which prevented the trans from shifting out of 1st. I got if freed up and cleaned it but still had very late and hard shifts at first but it gradually got better as I drove it.
 
Most likely a sticking TV valve, pretty common on a 700R4 that has some debris circulating in the system.

I know this is correct for 2 reasons:
1) The same thing happened to me once
2) Greg knows transmissions

It can be verified fairly quickly by dropping the pan, pulling the T/V , cleaning it and re-assembling.

The real question is why there is debris in there. Was it a one-time contamination from the adapter failure or is something inside wearing? What have you found in the pan?
 
The governor on mine stuck about 15 miles after a complete rebuild and had no obvious debris or gunk on it.
 
Started it today and it worked fine, then did it again. put it back on jack stands and ran it through all gears again until it shifted smooth. Now its fine.

The TV was good and stuck the first time I dropped the pan. So it could be sticking again. I was hoping the 30+ quarts of fluid I shoved through it on the flush machine would get that all out of there.

I will pull the gov and look it over and maybe even replace it. If that doesnt cure it ill drop pan and TV again for another cleaning.

Thanks for the advice.
 
They used to sell stuff like "Trans-Kleen" made by Siloo,and Marvel had a good automatic transmission treatment that cleaned the valve body and passages ,there is also products like K-W and Trans-Lube that were good for freeing up old gummy trannys ,we used to use that on a lot of the junkyard tranny's we'd pull from vehicles that sat a long time,if we had problems with them not shifting correctly,or delay going into gear...
 
I got in it today and it worked as it should again. Drove it all over with no issues.

Going to drain some fuid and ad soem trans x type stuff and just keep driving it to see what happens
 
This is the truck i'm working on. Aside from the paint ( was origianlly white) to the best of my knowledge that is an all original cab, Aside from the 1000 differant little things wrong with it, I'd say $1000 5 years ago wasnt to bad of a deal for a cab so clean :)

She has the other aluminum rim for it too

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Nice looking truck--wish mine was that solid and shiny...like the flat bed too..
--Hope the tranny additive helps cure the shifting troubles..
 
I would try a quart of Lucas trans fluid. A change in fluid and a quart of that unstick the shift valves in my cavalier. Worth a try.
 
Nice looking truck--wish mine was that solid and shiny...like the flat bed too..
--Hope the tranny additive helps cure the shifting troubles..


Thanks it is def a nice looking truck. Just wish not every backyard mechanic in the state had touched it. Thank god none of them thought they were bodymen
 
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