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Old 10-11-2004, 07:41 PM   #1 (permalink)
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700R4 question..

Hey guys, can you help me out with my wife's van?? She has a 94 Chevy G-20 van 4.3l and the 700R4 tranny. She has had a leak which is what I think was / is the front input shaft seal. Well today it started to leak really bad to the point that it was smoking from the fluid on the exhaust. So I dropped the tranny out and the seal really don't look bad. A friend / mechanic told me that these are common to have the pump go bad. So how can I tell if the pump is bad? Is it hard to change and just what do I have to do to replace it. It is not really hard to pull out, and I could "test" it with a new seal, but it is quite a waste of time.. Can somebody help me here??

BTW, I am going to copy this to the general board..
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Old 10-11-2004, 08:45 PM   #2 (permalink)
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Originally Posted by Firefyter_Emt
Hey guys, can you help me out with my wife's van?? She has a 94 Chevy G-20 van 4.3l and the 700R4 tranny. She has had a leak which is what I think was / is the front input shaft seal. Well today it started to leak really bad to the point that it was smoking from the fluid on the exhaust. So I dropped the tranny out and the seal really don't look bad. A friend / mechanic told me that these are common to have the pump go bad. So how can I tell if the pump is bad? Is it hard to change and just what do I have to do to replace it. It is not really hard to pull out, and I could "test" it with a new seal, but it is quite a waste of time.. Can somebody help me here??

BTW, I am going to copy this to the general board..
First thing to check is the convertor-has it turned blue or burnt the paint off if it's painted? Check the hub where the seal rides-no imperfections allowed. Behind the seal in the pump is a bushing that the convertor hub rides on. If there is too much clearance between a worn out bushing-then the front seal gets flooded with oil and wahlah leaks. In short yer going to pull that pump for inspection. Also there is a rubber o-ring around the outside of it-if there has been an overheating problem these will shrink and allow seepage-sometimes age just catches up to them. At any rate you need to pull the pan and remove the lockup solinoid and filter before you pull the pump. If you are in territory that you are not comfortable with-you may chose to find someone who can assist you. This is a pricey trans to begin with and several special tools will be needed/should be used. The thing that screws these pumps up is metal contamination-since the pumps are aluminum. So when the pan comes off-hope there are not metal cuttings in the magnet-if so yer looking at more time and dough fixing it right. As to the seal not looking bad-they too can shrink or lose their ability to seal on their own. Hang in there its not all gloom and doom.
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Old 10-11-2004, 09:27 PM   #3 (permalink)
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Damn Damn Damn... Not what I wanted to hear!! Friggin' Chevy only has 70K on it.. I just replaced the heater core that went out last spring (at 61k) on Friday

~Sigh~ What ya gonna do, Eh?

The converter is not painted, but has a swatch of paint near the hub that is just fine, the converter seal surface looks just fine too. I can drop it out in an hour or two, so I suppose the best thing is to replace the seal and hope for the best.. It will have to go out to someone if the seal does not do the trick..

Personaly, I think I should take the auto and stick it!! Hmmm, move the TV / VCR, drop in a 5spd... Yea, yea.. My wife knows how to drive a stick..
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Old 10-11-2004, 10:07 PM   #4 (permalink)
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Hmmm.. been searching a while now and it turns out I in fact really have a 4L60E.. But I assume that the same will go for this tranny as well??
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Old 10-12-2004, 06:53 PM   #5 (permalink)
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Well, I decided to go for it and put in the new seal and try it out.. So far so good, Not a drip out of it. (I tempoarly left the lower shield off so I could look in with a flashlight and see the seal itself..) I have let it idle for about an hour and drove it about 10 miles and it is still good.. So, how long before I can talk myself into the fact that it may of only been a seal?? It was dripping for a couple of months before it just let go and puked enough fluid to make it un-driveable.

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Old 10-12-2004, 08:36 PM   #6 (permalink)
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Well, I decided to go for it and put in the new seal and try it out.. So far so good, Not a drip out of it. (I tempoarly left the lower shield off so I could look in with a flashlight and see the seal itself..) I have let it idle for about an hour and drove it about 10 miles and it is still good.. So, how long before I can talk myself into the fact that it may of only been a seal?? It was dripping for a couple of months before it just let go and puked enough fluid to make it un-driveable.
If they are gonna leak=usually after a hard run-say like after a buzz on the freeway-or towing. Temp of the fluid has to operating temp cuz then it thins out some Hope u got it licked-but sure odd for a trans with that low of miles to have a seal crap out.
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Old 10-13-2004, 08:03 AM   #7 (permalink)
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Nope.. she puked out a bunch of fluid today.. So where do I go from here??
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Old 10-13-2004, 08:11 AM   #8 (permalink)
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Where did she puke from?
You did replace all the seals while you had it out right? Front, back, dip stick tube, speed sensor.
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Old 10-13-2004, 03:34 PM   #9 (permalink)
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Nope, just the front seal.. I didn't open the tranny up.. It was leaking from the input shaft. So tonight I pull it again and bring it to a tranny shop for them to look at it.. The tranny guy said that that bushing is a common problem as well.
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Old 10-14-2004, 06:51 PM   #10 (permalink)
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Well, all done and said.. it was the bronze bushing the torque converter rides on. It also damaged the hub of the converter enough to need replacement.. Not too bad, $211 to repair the tranny, $120 for a new converter..
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Old 10-14-2004, 07:12 PM   #11 (permalink)
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Well, all done and said.. it was the bronze bushing the torque converter rides on. It also damaged the hub of the converter enough to need replacement.. Not too bad, $211 to repair the tranny, $120 for a new converter..
It seems odd that a pump bushing would go at 70K until I read where it was a bronze bushing. I have yet to see the factory put one in a 4L60 or the 4L60E. Whenever they are used the convertor hub has to be hardened to withstand the extra hardness of the bronze. If you are the original owner and no one has been in the trans before now, then the factory installed that bronze bushing.
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Old 10-14-2004, 10:19 PM   #12 (permalink)
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It seems odd that a pump bushing would go at 70K until I read where it was a bronze bushing. I have yet to see the factory put one in a 4L60 or the 4L60E. Whenever they are used the convertor hub has to be hardened to withstand the extra hardness of the bronze. If you are the original owner and no one has been in the trans before now, then the factory installed that bronze bushing.
Well don't hold me 100% on it being bronze.. I am almost positive that is what the tranny guy told me and he is a very good shop.. But it was that bushing that let go. he said that it spun and also had slightly damaged the converter hub. He said it was unlikely to seal and highly recomended replacing the converter. He poked around the tranny to see if all else looked go and said it was better than he expected. So that is good.

BTW, with a new converter, what is the best way to fill it?? Should I try to pre-fill it prior to installing it on the tranny or just add the fluid like normal and let the pump fill it up?? I have never put in a new one before.. Any idea on capacity for this tranny (100% positive it is the 4L60E now)
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Old 10-15-2004, 02:23 AM   #13 (permalink)
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yes the bushing goes out every so often. on one tranny i did, the pump housing was cracked and let the bushing spin, new pump half was ordered to solve that problem. this tranny was also a 4l60E and yes it is a bronze bushing from the factory.

put atleast 1 quart in the coverter.

filter change is 5-6 rebuild with new converter is 9-10 (don't recall off hand). i usually just buy a case for every tranny i do.
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Old 10-15-2004, 06:30 AM   #14 (permalink)
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In order for that bushing to spin in the pump-there would usually be some history of overheating causing the aluminum pump bore to expand defeating the interference fit of said bushing in the bore or enough heat or lack of lube causing it to momentarily seize to the convertor hub. Hang in there-sounds like yer gonna be fine.
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Old 10-15-2004, 06:05 PM   #15 (permalink)
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WTF!!!!!!!!! So tonight, I pay the $211 bill at the tranny shop, brought my new converter for him to measure the hub (they said it looked just fine as they didn't want me to buy a $120 converter, but to buy their $275 one.) I get it all in and it is leaking just a fawkin bad!!! What the hell!! I have to pull this out a thrid time this week!! Now i can't wait for them to say that the "other brand" converter is all the problem.. Is this possiable?? The guy checked the hub with a caliper and checked it against a good unworn spot on my old one and they were the same.. We are talking about a small stream at a low rev..
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Old 10-15-2004, 06:14 PM   #16 (permalink)
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did they tell you what they replaced? do you know if they removed the pump?
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Old 10-15-2004, 06:22 PM   #17 (permalink)
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He said that they inspected the pump closely and there was no cracks or damage.. Ther replaced that bushing, some seals and the filter. I know they did remove the pump.. I just don't buy the "could by my converter bought for that application" and measured by them, to of been so poorly built that it is leaking this bad. I pulled into my garage with it running, less than 5 min later there is a 1 foot puddle on the floor. When, my wife reved it a little a small steady stream ran out of it right at the front seal.
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Old 10-15-2004, 06:47 PM   #18 (permalink)
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where did you get the converter, and what brand is it if you know. i only use a few brands of remanufactured converters.

there is nothing other than the bushing and seal, unless the pump body is wore. but if they inspected it

i wonder if you have another problem, are you 100% positive that its coming from the seal? there are orings inside the head of the bolts for the pump, i don't think any of them would leak that much tough. but they do screw into the pressure ports. if they took the pump off they should have replaced them, i always do.
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Old 10-15-2004, 06:49 PM   #19 (permalink)
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Quote:
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He said that they inspected the pump closely and there was no cracks or damage.. Ther replaced that bushing, some seals and the filter. I know they did remove the pump.. I just don't buy the "could by my converter bought for that application" and measured by them, to of been so poorly built that it is leaking this bad. I pulled into my garage with it running, less than 5 min later there is a 1 foot puddle on the floor. When, my wife reved it a little a small steady stream ran out of it right at the front seal.
I expect the coverter to be fine. What has happened is that they have not fixed the original leak. What to do? Well, either the pump has a crack through the bushing bore to the outside-or the bushing has spun and slid forward blocking/restricting the drain back hole and the seal is getting flooded with oil and some gets by. The interference fit of that bushing is important and once they spin then that fit is compromised. Builders are aware of the procedure to stake the bushing to prevent it from spinning again and walking forward into the seal cutting off the drain back hole in the pump. Next time you pull that trans-yank the convertor and carfully remove the seal-then get a strong light and look at the bushing it better be flush with the bore and not walked out towards the seal. Yes you are gonna destroy the seal in doing so-they are like 2-3 bucks retail. Hang in there.
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Old 10-15-2004, 08:09 PM   #20 (permalink)
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Well, damn thing is back out and sitting in the trailer.. I agree with the builders point that he only likes to use his brand of converters, but we are still talking about a brand new (for this application combo) that they personaly inspected and checked the hub of the new one with calipers.. When I got back from test driving it and found the leak I dropped the Y pipe and removed the lower cover. I then bolted back the Y pipe and started it up. small drip from the seal when I had my wife rev it a little bit I got a bath that looked like a dog pissing on me. nice small steady stream from the seal area. I am not going to yank out the seal, It is going back to them to look at it. Not bad time to R&I though. 1.5 hours to jack & secure it, yank the tranny, hook up my trailer to the Jeep, put the tranny in a constructiuon trash bad & wire tie it (it's raining) and then go take a shower & get dressed.. I have done this too often this week..

I still think there is a underlining problem they missed (or they just screwed it up)
I'll let you all know...
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Old 10-15-2004, 08:52 PM   #21 (permalink)
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I am not going to yank out the seal, It is going back to them to look at it. Not bad time to R&I though. 1.5 hours to jack & secure it, yank the tranny, hook up my trailer to the Jeep, put the tranny in a constructiuon trash bad & wire tie it (it's raining) and then go take a shower & get dressed.. I have done this too often this week..

I still think there is a underlining problem they missed (or they just screwed it up)
I'll let you all know...
I believe you beat flat rate time on that
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Old 10-15-2004, 09:18 PM   #22 (permalink)
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Oh yea.. and I don't have a tranny jack.. That was with using ratchet straps!!

Wish I could have the pay for that flat rate job right about now..
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Old 10-18-2004, 03:45 PM   #23 (permalink)
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Well, much to my joy.. I dropped it off today and they didn't make a fuss. Called me about an hour later and said "the input seal was defective" I am like, Ok... So wehn I put a seal in and it leaked, they you all put a couple hundred bucks in it and it still did the same thing, it is just a bad seal, Eh? Once at the shop the guy told me a second story, seems as though that this tranny can have 2 seals depending on application. The wrong seal was installed and not checked against my new converter (though, they did have the old one..) So I put it in and have driven it about 20 miles and it is bone dry.. Time will tell. I am just happy it did not cost me more $$$
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Old 10-19-2004, 01:40 AM   #24 (permalink)
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acording to my books, there is only 1 seal for all 700r4 and 4L60E trannies.

im wondering if they put a seal for a th350 in it, the seal hub on a th350 is a bit bigger (1.873 for th350 and 1.748 for 700r4) and the outside dimentions are identicle.

i wonder if they said that to cover their ass cause someone doesn't know how to tell the difference.

i think when you replaced the seal, the bushing was bad.

glad you got it fixed.

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Old 10-19-2004, 07:51 AM   #25 (permalink)
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That very well may be the case. He was hitting more on the point that their stock room was messed up and that the outside of the 2 seals are the same, but one is a little larger. They fully admitted it was their screw up. I also believe the bushing was bad. I am an Insurance Appraiser and deal in this city/town and know the overall reputation this shop has and it is very good. I am just glad it is done with.. Damn, I must of gone thru 8 gallons of fluid this week!! My wife is more glad it is done.. Now here heater core has been replaced, new Pioneer front speakers, tranny leak fixed.. Now all I need to do is send it down for an alingment and have a new pair of tires I have sitting in my shop installed before the snow hits..
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