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Tranny pump seal; a few questions

Discussion in 'The Garage' started by Jagged, Sep 16, 2005.

  1. Jagged

    Jagged 1 ton status

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    Well y'all it's been a while since I've posted here, some silly thing about being in a desert half a world away. Now that I've returned, I see my truck didn't fix itself while I was gone :(

    Anywho, I'm gonna be changing the pump seal on my tranny (700R4), I'm just looking for some pointers and any info that would be nice to know. My plan of attack is to put the truck on a lift and drop the tranny to change the seal.

    I do have a couple stupid questions, however. Will I need to drain the transmission before removing the seal? And how much fluid can I expect the cooling lines going to the radiator to expunge?

    Thanks in advance for any info!
     
  2. randy88k5

    randy88k5 1/2 ton status

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    Eh, from the lines, I would say 2 qts max. The torque converter will hold a few too. I would drain the fluid, cause this would be the best time to get the maximum amount of new fluid in there. Replacing the filter should be a given if your gonna change it. Torque converter will be a little heavy and severly oily if your front pump seal is leaking, so be careful. Wear steel toe boots if u got it on a lift. An angled prybar tip works pretty well to hold the flexplate still while you remove the 3 TC bolts with a wrench.

    Seal will probably be a PITA to get out, Id use a seal puller to make it easier. Make sure you dont damage the drive pins for the pump, as they are pretty close to the seal. I think some people also recommend locktite on the seal, but Im not positive.

    Did I forget anything?
     
  3. Jagged

    Jagged 1 ton status

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    Good idea with the filter ::bangs head on table:: Should have just assumed I was gonna change the fluid+filter, but 18 hours on a jet will warp your mind a bit ;)

    Steel Toe Boots == always, courtesy of old boots the military issued :)

    How difficult is it to press the seal (would I need a press of some sort to get it in?)

    Yeah, I've heard of using loctite on seals as well, I used it on my front crank seal (or whatever you call it... between the timing chain cover and the crank). And speaking of that, I shouldn't need anything like a speedy sleve for the input shaft of the tranny should I?
     
  4. randy88k5

    randy88k5 1/2 ton status

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    As for a press, no way. Way too much time. Pump would have to come out, and those things seat in there pretty good. You would need to drop the valvebody and knock it out from the back, unless you had a special tool for it. Use a bearing/seal driver set (rod with several attachable discs) to install it. Or just be very gentle and slow with a regular hammer.

    No need for a sleeve, unless the aluminum has been eaten away. Hopefully there is just a tear or hole in the seal.
     
  5. Jagged

    Jagged 1 ton status

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    Ahh I gotcha. Yeah, this seal is just an educated guess as to what is spooging tranny fluid.

    I attached a photo of what the underside of my truck looked like when I first spotted the problem. After warming up and driving for a while, when parked tranny fluid would drip out of the drain hole on the flexplate cover (about 1 drop every 2-3 seconds).

    They way I see it, is that seal is only a few bucks, so I already have it on hand. Once the tranny comes down, I'll be able to get a definate answer as to what's actually broke.

    2005_0606Image0014_scaled.JPG
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    I've popped those seals out with a screwdriver and a hammer, a bit tedious, but it's just like any of the other metal ringed seals, they are hollow and deform pretty easily. Smack the outside edge of the seal towards the input shaft, (so you aren't putting force on the pump really) once you get a good sized space, use the screwdriver to pry it out.
     
  7. jekquistk5

    jekquistk5 Weld nekid Premium Member GMOTM Winner

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    I'm taking my tranny out to do the samething today. Atleat I hope everything goes right. Anything I have to watch out for when taking the tranny off?
     
  8. Jagged

    Jagged 1 ton status

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    Don't drop it? :haha:

    On a serious note, some PB Buster might help a lot. If you havent had to unbolt the bellhousing or the flexplate cover (aka rock shield), or any of the braces and mounts recently, those bolts will be a bit of a bear. If you have access to air tools... use them.
     
  9. 89newtome

    89newtome Registered Member

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    replaced my front seal 3 times

    I know this post is a little late, but maybe it may save you some trouble that I had. I replaced my front seal 3 times. It started leaking about 4 days after I changed it the first time, kinda aggravated me, I thought I got a defective seal. Changed the seal a 2nd time, started leaking again within a week, so I thought maybe I screwed it up when I installed it. Changed the seal a third time. Then it started leaking again, now I knew something was wrong. I wasnt going to do it again, so I checked to see how much to have a transmission shop change it, well I figured I would drive it for a while until I came up with some more money. drove it for about a month, well now I am looking for a new trans. I talked to the trans shop, they said that there is a bushing in the pump where the torque converter rides that wears out and the converter will wobble and wipe out the front seal. This maybe something you want to look at while the trans is out.
     
  10. Jagged

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    Yeah, I just changed the fluid and filter today in an attempt to avoid changing the pump seal. The 700R4 is getting ready to bite the dust according to what I saw in that pan.

    Good news is, I have a TH400/NP205 on the way :)
     

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