RockinGTA89

i've just recently installed a 700r4 tranny, actually it's a 1993 design, (the last year style) into my pontiac t/a...the trans has a minor aftermarket components including a vette servo, a S-10 style torque converter, and a tci deep trans pan with oil cooler. Now i didn't built the trans, only installed it and of course we did replace what was needed to transfer from the old transmission to the upgraded one, aka: speedometer sensor, governor, internal wiring harness, tcc switch, and a (in valve body) pressure switch that was needed to be change over from the old one to the new one.
At first test drive the trans ran great, shifted firm, and was awesome off the line, chirping the tires from 1 to 2 to 3rd...however after a few hours of driving the vehicle, it had developed a low hum noise coming from the trans, then i realize when i was driving in a parking lot i had no reverse, and a very irratic 1st gear. After going from 1st to 2nd the shifts from the vehicle was able to accelerate normally. Now today, after driving the car, the car does shift fine from 1st to 2nd however it won't shift any higher or accelerate causing the engine to rev up to 3000rpms plus, and i do have reverse which the problem with that, hasn't occured since. I did take line pressure readings and conducted a road test. Here is what i found and if anyone can help, please give me a clue on what's occuring here...I've been trying to find specs. on pressure readings but haven't had any luck in doing so....

Idle in park: (cold to warm vehicle) 80psi
reverse (holding brake): 125 psi
with rear wheels in air/ accel. :same
Neutral: 80psi
Overdrive- 75psi and with wheels moving, same reading (vehicle on lift)
Drive- 75psi and with wheels moving, same
however on road test, o/d and drive while accelerating the psi does goes slightly up to like 85psi but again the vehicle won't shift from 2nd, causing the rpms to jump
Low 2- 200psi in gear or even when driving...
when driving in L2, the trans does change from 1st to 2nd and stays there and i can get the car to go up to like 35mphs without any problems of couse the engine brakes after decel
Low 1- 200psi in gear or even when driving, stays in 1 and engine brakes vehicle when decel

once the car shuts off, psi drops to 0

I wanna speculate that the oil pump is going, but if it's so, wouldn't it have problems thru all gears and reverse?....i hate to think that something is occuring in the valve body...

any help would be appreciated

Mikz86TA

iTrader: (4)

Not sure if this will help, but my source says 700R4 pressures are as follows : 55-75psi in Drive Range (D or OD) and Neutral , 160-190psi in Low Ranges (1 or 2) , and 85-140psi in Reverse. All these were with brakes applied. Your pressures look fine to me, but a more experienced person will probably ping in. Good you have a pressure gague and have provided alot of info. I hope you figure it out. Im in my own 700 issue right now =). One suggestion is to check the 'line pressure rise' with the TV system. You can do this by hand..watching the pressure gague and tug the TV cable at the carb/tbi/tpi.

RockinGTA89

thanks for the help there buddy, i appreciate it. The specs. you give sound within reason for sure to what i stated, as i verified it with a trans shop that we (our shop) deal with, and they too say the pressures sound like they're within specs as well. They say it's possibly that the governor may be acting up and the weights inside the governor may be the problem or possibly that a stuck valve inside the valve body is acting up. I will check out that test you provided for the tv and post my results.
I've also have conducted a stall pressure test with the brakes on, in reverse and in drive...and that to as the trans shop specified shows that it's also within specs. (which is like 160 to 200psi) I'm getting 175 plus in both drive and reverse...so more then likely it isn't a oil pump but rather something else...i'll keep everyone posted...

Mikz86TA

iTrader: (4)

Cool. Definately keep posting info. I like to gain info on possible problems I may have one day. The governor is an easy check. Good Luck

RockinGTA89

well just to keep ya updated on what's going on, i just did a few things today and took the liberty in inspecting all the swapped stuff we did. I looked at the governor and apparently it's in good shape and weights on the inside works properly, even the valve inside the governor is okay. I did that tv valve pressure test as you said Mikz, and of couse the pressure increases as you pull the cable...i drained the oil just to get a better look in the pan to see if anything was busted out, of couse nothing but the oil is pretty dirty already, so i drained it and put in fresh ATF. I pulled the "4th gear pressure switch," which is what we transfered over from the ol tranny and it looks okay, being a single wire switch, i really didn't test for conductivity, more or less i'm assuming it's okay....probably should of tested it...in any case the way i see it now, it's more of a problem with possibly a stuck valve in the valve body or something going on with the valve body. I guess i'm just gonna end up taking it to a professional trans shop to get it looked at, even though i should be able to learn to do this on my own, however i really don't have to time or cash to fix up everything. I just want the damn thing to shift normal like it did before. oh well :/

Mikz86TA

iTrader: (4)

IDK bud. I learn as I go too. Ive had numerous trannys and all have gone south with different problems. At 1st you said something about a whine. Most of the time thats a pump issue. Was this tranny rebuild prior to you getting it or did you have it done?