O/T Chevy Transmission Problem

Friend of mine called tonight. The 700R4 transmission in his 83 Chevy S10 will not shift into 3rd or overdrive. It worked fine when he parked it the night before. The next morning 1st and 2nd work but no shift to 3rd or 4th. I don't know the history of the truck. He says the fluid is clean with no burnt smell. I don't know much about the 700R4's, could it be something stuck or is it rebuild time?

Could be a lot of things, but check the fuel filter and the TV cable first.

Allan

Could be a lot of things, but check the fuel filter and the TV cable first.

Allan

there is an aluminum valve that slides back and forth in there I don"t remember the name but it will delay shifts I have had a couple stick. I know b&m makes them too because if you buy a shift kit a new one comes in the kit.

That was usually the modulator (vacuum solenoid)
on the older automatics. Check the vacuum hoses first. Hal

here is a filter out of my 84 s-10. The first 28 degree morning to work made it not run and die. I neglected this filter, its just an old bomb. But i never thought they could get this bad. That is ICE on the filter. Allen is so right on the injected engines.

Bull guy, there's NO vacuum modulator used on a 700R4. NO vacuum hoses, either!

It's hard to believe any 700R4 from 1983 is still working and never been torn down. They were absolutely awful until they got many updates. By 1985 they were better and by 1988 all the bugs were worked out.

With all the 700R4/4L60 units, much is controlled by the TV cable, stop-light switch, and a few emissions controls. But, for 3 and 4 problems, it's probably internal. Bad accumlator, bad check ball, 3-4 clutch problems, etc.

Throttle valve.

Original design "floats" between oil line pressure and against the TV cable/spring.

Yep, when that joker sticks, shifting is all over.

Allan

The "worst" one I ever faced was a loose pin in the aux valve body.

Had to call the big dogs in Minneapolis on that one to get some ideas of what was going on.

Ate my lunch for two solid days before I finally found it. :>(

Allan

Maybe I should of qualified my comments. They were absolutely awful when coupled to V8s. May of not been so bad with small engines in the S10 class. The 82s to 84s need many updates. The 700R4 was built onto the TH350 platform, and the first 350s also had a high failure rate. Later, they were great.

The two local Chevy dealers near me refused to sell any 700R4 truck if it was doing to tow a trailer from 1982 to 1984. They swapped in TH400s for that. It's also why the "mechanical modulator" kits were invented for the TH400s. Kit was made for converting 700R4 trucks to TH400. The kit was made so a TH400 could be hooked to the TV cable for the OEM 700R4. I've got two 83 plow trucks with that setup.

I thank the early 700R4s for all the dead and abandoned diesel trucks I bought cheap with low miles in the early 80s. They were dropping dead all over and the trans-shops did not have a good fix - except to swap in a TH350 or TH400. And, many did.

Bad 700R4 transmissions along with bad injection pumps led to many GM diesel truck taken off the road with very low miles on them. I bought many, dirt cheap. By 1985, the transmissions and the injection pump problems were fixed.

And, they still turn up. A few months ago I bought an 84 diesel Blazer with 45K original miles on it. The trans blew. They got it fixed and then the injection pump died. They stuck it in their barn and there it sat for many years. Old guy died, and I just bought it for $250. Got it running and trans-oil came pouring out of the front of the "rebuilt" trans.

"Ate my lunch for two solid days before I finally found it". Am I the only one who doesnt get it? bill m.

Dealer techs generally work on a commision basis.

That tranny pays something like 11 hours max to remove, completely overhaul and then reinstall and road test.

Not to mention that ya gotta guarantee your work for 120 days or so.

Anyway, after the allotted clock time has run it's course; there is no more pay. None. Ya work totally for free until the thing is repaired and operating as it should.

Oh, and did I mention that GM pays no diagnostic time whatsoever? Ya gotta know what’s wrong with the rig when it pulls in the door. Just by the write-up on the work order and/or a road test.

So, ya get really good at knowing what is wrong just by it's symptoms going on at the time.

Allan