In addition to my Caprice Wagon, I have a '93 Suburban with a 6.2L diesel and a 700R4 transmission. I originally pulled the transmission from a diesel 1986 C2500 Suburban along with the 6.2. I installed a governor kit to make the transmission upshift sooner shortly after the conversion on my 93 was complete (it upshifted too late and it held the gears too long). After the governor was upgraded, I have had no trouble since until now. Recently I have had an unusual issue with the transmission "neutraling" out on the 4-3 downshift. If I force a downshift with the accelerator, it will rev like I am in neutral. If I let off the throttle it re-engages 4th. If I pull the shifter into drive from overdrive it will immediately drop to 3rd. If I slow down to the automatic 4-3 downshift point (about 35 mph) it will drop to 3rd without a hiccup. The problem is just on a throttle forced downshift, and the transmission doesn't do this all the time, but it seems to be an issue when the trans is warm where sometimes it will work normally, and other times it will act like an imbecile. All other functions are normal, and it upshifts fine. The fluid is cherry red, but I dropped the pan to service the filter anyway, just to be safe. The inside of the trans is clean and there was no evidence of significant wear in the pan. If I use manual drive (manual 3rd) it drives seamlessly. In overdrive it performs normally as well, except for the 4-3 downshift, which is sometimes a 4-neutral downshift. Any trans gurus out there with an idea of what might be wrong?
More 700R4 problems. Son just called. He put a rebuilt 700R4 supposedly modified in his 1985 Chevy truck with 383 SBC engine. This was about four months ago. It has worked flawlessly until this morning. He now has only low and second. He says it is very responsive like before in those two gears. But even in second when he lets off the accelerator it goes into neutral and idles. It should be revved up and act like an engine brake. Fluid is full, and linkage like it should be. He's calling the place he bought it to see about the gaurantee.
I was thinking maybe a 3-4 shift solenoid but all I can go by is what I sell here at Napa, I am not a trans guru by any means. Lately if I give my opinion about any type of car repair it seems someone comes along to tell me how wrong I am, so by all means don't hold me to this guess.
Don't be hard on yourself Dewey - you're trying to diagnose a car/problem you can't see, hear or touch based on a written description. I always appreciate any troubleshooting tips the members provide.
I agree. Even when a mechanic looks and listens it's often just a guess. Son drove his truck here about 18 miles to swap vehicles. Said it got a little warm but did fine in second gear. He sure has tranny troubles. Seems to be driving almost like he has good sense so I have no idea what happened on his truck. I do know the cable adjustment has to be right on. But after four months working properly I'd think it was. He put the 2004R in my wagon and it's done great for years. Don't want to steal this thread but seems like a good place to add a similar problem. Kill two tranny problems with one stone!
Dewey, Don't sell yourself short. A good partsman is worth his weight in gold. Certain vehicles are prone to certain problems, and he usually knows what they are. I've had a couple over the years. Sometimes a phone call to them with certain symptoms on a certain model will save diagnostic time; and sometimes they would call other shops to get opinions for certain hard to diagnose problems. In return, the Go To Guy reaps the rewards in parts commissions cause you always ask for him when ordering parts.
Argo: It sounds like a valve body problem. The TV valve is notorious for sticking on these. However, I don't believe that is your problem. Hard to say what the problem might be. The only thing changing on a 4-3 downshift is the band is coming off and the input sprag is reapplying. There is a chance the input sprag is slipping. But, I believe you'd feel that as it's function is relied on in 1, 2 and 3. It is over-run when 4th applies. Something else could be slipping. A checkball no seating. Various possibilities without getting into the trans. CatModelT: He may have burnt or stripped the 3-4 clutches. Broke the fwd planet ring gear hub or stripped it's splines. Dewey: Sorry is has to be me, but in a 700R4 the only solenoid is for TCC lock-up. As a mechanic, I have to say keep up the good work in getting us to correct parts. Mark Berkshire Transmissions North Adams, Massachusetts
Thanks Mark. Son hasn't heard anything yet from the place he bought the tranny. It's a good well known shop so we are hoping he will get another replacement or this one repaired. The transmission seemed strong and worked great for at least four months, I believe.
Wholly Crap Mark. Thank you for taking the time to Chime in... Not everyday a pro steps up and gives free advice... Thank you Thank you...
Thanks for the back up all, I guess I wasn't being down on myself necessarily I just know my limitations when it comes to transmissions. I really appreciate everyone giving me props for giving my opinion. You guys made my day! :2_thumbs_up_-_anima Thanks to Mark, a real trans pro for stepping up!
