Transmissions and Drivetrain Need help with your trans? Problems with your axle?

Replacing Front Pump Seal

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Old Sep 26, 2011 | 03:09 PM
  #1  
amber lynn's Avatar
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From: Hudson, MA
Car: 1988 Pontiac Firebird
Engine: 5.0 305 TBI
Transmission: THM700R4
Replacing Front Pump Seal

Hi everyone. This is my first post, so my apologies. I searched for forum to see if something along these lines have already been answered and had no luck. I just purchased my second third gen. It's a 1989 Pontiac Trans Am GTA WS6. I was told at purhcase the front pump seal on the tranny was bad and that's why it was parked three years ago. Anyway, my mechanic priced me anywhere between $600 and $1100 depending on if the seal is just weaping from sitting (has low miles for age so has sat most it's life) or if something more was wrong.

Two questions: If I have a lift to use for a day how hard is it to replace this? Should I repalce the torque converter and anything else when I do it?

Or does anyone know if I can take the Tranny out of the 1988 Pontiac Firebird with a 305 TBI in it?

Or would I be better off getting a tranny from a junkyard? Any advice, things to watch out for or anything will be helpful.
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Old Sep 26, 2011 | 07:25 PM
  #2  
jmd's Avatar
jmd
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From: Aridzona
Car: `86 SS / `87 SS
Engine: L69 w/ TPI on top / 305 4bbl
Transmission: `95 T56 \ `88 200-4R
Re: Replacing Front Pump Seal

If you know the leak is out the front from the converter area above the pan, go for it.
Unfortunately for the removal of the converter, you have to back the trans. off enough that it requires basically the same work as fully pulling it down.
I've never used a lift and a trans. jack only a few times out of many to R&R.
Some cars you can put the car on stands, disconnect most everything, jack up the nose of the engine so the trans. is pointed down, insert long 3/8-16 bolts that are threaded only toward the end into the bottom two bellhousing bolt holes, pull the other 4 and slide it back on a jack enough to get the converter out and get a new seal on. Not sure if he F floorboards will let you d this and it'll be easier to get the seal in with the trans. down anyway.

Make sure and inspect the snout of the converter for wear at the seal mating surface and cracks at the two notches. And find a proper flat faced round item that will drive the seal in evenly. Other than that, it's about like any other 2WD automatic R&R.

Also, when putting the converter back in, press it gently into the pump and spin it a dozen times or better at the same time. It has to mate properly with the input shaft and stator support splines as well as the pump drive tangs. When it all goes back up to the engine, there will be a noticeable gap between the converter and flexplate. If there's not, don't under any circumstances force it.

FWIW, the last R&R I did on an automatic was August a year or two ago (Yes, it was 120 out) and I lazily pulled a 700-R4 and installed a 200-4R in under 8 hours including breaks.
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Old Sep 27, 2011 | 01:45 AM
  #3  
3rdgenmaro's Avatar
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From: Lincolnton, NC
Car: 88 IROC
Engine: 97 5.7 Vortec LT4 hotcam
Transmission: 700 r4
Axle/Gears: 3.73
Re: Replacing Front Pump Seal

I know the feeling. Im fixing to do this same thing the next chance I get.

Here is my plan.

1. Jack up both ends as high as my jackstands will allow.
2. Unhook TV cable
3. Unbolt driveshaft (4 bolts on the rearend) and remove drive shaft.
4. Unbolt torque arm mount from trans.
5. Remove 3 torque converter bolts, slide converter all the way towards converter.
6. Place jack under trans.
7. Remove trans mount bolt.
8. Remove 4 crossmember bolts.
9. Lower jack to let the trans tilt as much as possible. Keep some weight on the jack.
10. Unhook Speedo cable, Lockup wiring harness, and fluid cooler lines.
11. Remove bellhousing bolts.
12. Drop trans out.
13. Pull converter out
14. Replace seal.

15. Reinstall, double check TV cable adjustment, replace fluid.

Last edited by 3rdgenmaro; Sep 27, 2011 at 07:36 PM.
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Old Sep 27, 2011 | 08:11 AM
  #4  
amber lynn's Avatar
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From: Hudson, MA
Car: 1988 Pontiac Firebird
Engine: 5.0 305 TBI
Transmission: THM700R4
Re: Replacing Front Pump Seal

Thank you both for your reply..it sounds scary (: I've R&R'd entire tranny's, but I'm a little reluctant to pull out seals and torque converters and then try to put it back together... anything I need to watch out for?? JMD, I'm going to AZ on Thursday..maybe you could show me how to do one? lol
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Old Sep 27, 2011 | 10:01 AM
  #5  
amber lynn's Avatar
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From: Hudson, MA
Car: 1988 Pontiac Firebird
Engine: 5.0 305 TBI
Transmission: THM700R4
Re: Replacing Front Pump Seal

Also, does anyone know if the bolt pattern and tranny are the same from my 1988 Pontiac Firebird with a 305 TBI for the 89 GTA? Would I be able to swap them out?
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Old Sep 27, 2011 | 10:14 AM
  #6  
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From: Il
Car: 1989-92 FORMULA350 305 92 Hawkclone
Engine: 4++,350 & 305 CIs
Transmission: 700R4 4800 vig 18th700R4 t56 ZF6 T5
Axle/Gears: 3.70 9"ford alum chunk,dana44,9bolt
Re: Replacing Front Pump Seal

Wow that shop is tryn to stick it to you.
Its a 6.00$ part.
with a lift its a 3-6 hr job depending on how fast ya are. Even on the ground Ive done them in 3hrs.. Gettn older and slower now lol
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