To Flush Or Not To Flush?
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From: Regina, Saskatchewan, Canada
Car: 1990 Trans Am GTA
Engine: 350 TPI
Transmission: 700R4
Axle/Gears: 3.42's
To Flush Or Not To Flush?
That is the question with my current transmission. My car has just over 171km's and the tranny fluid is still pink but is a somewhat dirty. I've owned the car for 2 years so far and have done no maintenance on the tranny. I am not sure what the previous owners have done on it either. I was thinking of doing a flush but heard they can be destroy your transmission but also hear they are vital. So maybe just change the tranny oil and filter first then see? One more thing, awhile ago I noticed something on a few receipts from the previous owner. Short story, the odometer may have been rolled back over 50,000 kms. I heard tranny flush's are not recommended over 200km's sure not sure if I want to risk it. Any ideas or advice? Thanks, Josh
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Member
iTrader: (1)
Joined: Oct 2007
Posts: 141
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From: Regina, Saskatchewan, Canada
Car: 1990 Trans Am GTA
Engine: 350 TPI
Transmission: 700R4
Axle/Gears: 3.42's
Thread Starter
Member
iTrader: (1)
Joined: Oct 2007
Posts: 141
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From: Regina, Saskatchewan, Canada
Car: 1990 Trans Am GTA
Engine: 350 TPI
Transmission: 700R4
Axle/Gears: 3.42's
Re: To Flush Or Not To Flush?
I asked to get a general consensus of the people on thirdgen.org what they would do since we all own thirdgens not just from some random site. That's why this site is there to help others and give advice jeeze...I rather ask and know rather than having my transmission going from something that could of been prevented.
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Joined: Apr 2008
Posts: 77
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From: Goddard, Kansas
Car: 1990 iroc-z
Engine: 350 tpi
Transmission: 700r4
Axle/Gears: 3.23 posi
Re: To Flush Or Not To Flush?
dont flush just have the fluid changed ive heard horror stories where people flushed a transmission and it stirred up all sorts of junk in the convertor and tranny and caused failure ive always just changed fluid and filter
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Joined: Nov 2006
Posts: 248
Likes: 0
From: Tx
Car: 86 Camaro
Engine: 305
Transmission: 700r4
Axle/Gears: 3.73
Re: To Flush Or Not To Flush?
Just drop the pan and change the filter and fluid. Any trash that might be left floating around will get trapped by the new filter. Some years back I had this same discussion with a custom trans builder who sells nationally for everything from serious sled pulling trucks to drag cars and that's what he recommended, never had a problem.
Dan
Dan
Joined: Jul 2005
Posts: 1,428
Likes: 2
From: Guilford, Connecticut
Car: 1988 IROC-Z camaro
Engine: 355 TPI
Transmission: tko 500
Axle/Gears: Dana 44 3.31 posi pbr brakes
Re: To Flush Or Not To Flush?
Dropping the pan and just changing the filter and filling it up again does nothing. There is something like 11 quarts of oil in the transmission and lines. When you drop the pan you only replace around 6. The second you fire it up and drive it around the block the fluid will be dirty again anyways. Do yourself a favor and get it flushed. I have flushed a tranny with 120000 miles and it had no ill effects. I have also flushed my current cars tranny twice now (72k).
To put it another way...if your tranny is only being held together by the fluid like some claim theirs were...then its on its way out anyways. If it seems to shift fine the way it is and the fluid is just a bit gross...flush it.
To put it another way...if your tranny is only being held together by the fluid like some claim theirs were...then its on its way out anyways. If it seems to shift fine the way it is and the fluid is just a bit gross...flush it.
Re: To Flush Or Not To Flush?
Dropping the pan and just changing the filter and filling it up again does nothing. There is something like 11 quarts of oil in the transmission and lines. When you drop the pan you only replace around 6. The second you fire it up and drive it around the block the fluid will be dirty again anyways. Do yourself a favor and get it flushed. I have flushed a tranny with 120000 miles and it had no ill effects. I have also flushed my current cars tranny twice now (72k).
To put it another way...if your tranny is only being held together by the fluid like some claim theirs were...then its on its way out anyways. If it seems to shift fine the way it is and the fluid is just a bit gross...flush it.
To put it another way...if your tranny is only being held together by the fluid like some claim theirs were...then its on its way out anyways. If it seems to shift fine the way it is and the fluid is just a bit gross...flush it.

I agree with the above Post and I also stated this in my previous Post. If you want to belive in this Shadetree Mechanic Myth, go ahead. But my opinion will always be a FLUID change for anything mechanical is always better then none.
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From: Cleveland, Ohio
Car: 89' IROC-Z
Engine: LO3
Transmission: 700R4
Axle/Gears: 10-Bolt/2.73
Re: To Flush Or Not To Flush?
My transmission shifts horrible. I plan to adjust the TV cable and have my transmission flushed, torque converter and all. I will also be replacing it with a new filter and seeing if that helps my shifting problem...as I don't think my trans is bad, just not adjusted correctly (as it just had a motor rebuild done before I bought it, and I'm hoping they never adjusted it back).
If time comes, I will post my results with pictures of before and after of my fluid, as well as a report on how my transmission will then shift.
P.S. My buddy does trans flushes and says all they do is drain all the fluids (TC as well), add new ATF fluids. Then they run the car for 30 minutes or so. Shut it off, drain the fluids again and refill again, then your good to go. This is what I will be doing except I will replace the filter ($12 new so no big expense) with the new fluids, have the car ran then drained and a new filter put in again in which I will have my RP put in for the final change, kind of changing it twice to ensure I can get the most crap out of my transmission.
Take care.
If time comes, I will post my results with pictures of before and after of my fluid, as well as a report on how my transmission will then shift.
P.S. My buddy does trans flushes and says all they do is drain all the fluids (TC as well), add new ATF fluids. Then they run the car for 30 minutes or so. Shut it off, drain the fluids again and refill again, then your good to go. This is what I will be doing except I will replace the filter ($12 new so no big expense) with the new fluids, have the car ran then drained and a new filter put in again in which I will have my RP put in for the final change, kind of changing it twice to ensure I can get the most crap out of my transmission.
Take care.
Supreme Member
Joined: Dec 2005
Posts: 1,244
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From: Texas City, Texas Area
Car: 89 RS, 92 Z28
Engine: 305 TBI, 350 TPI
Transmission: 700R4 Both Cars
Axle/Gears: 3.23 Posi.. 4 wheel disc both cars
Re: To Flush Or Not To Flush?
I did mine a long time ago, and have had no problems with that aspect of it..My car had 136,000 miles on it when I did it, it has about 170,000 on it now...
Supreme Member
Joined: Nov 2008
Posts: 1,146
Likes: 6
From: Houson
Car: 86 Firebird
Engine: 305 SBC
Transmission: 700 R4 TCI
Axle/Gears: 3.42
Re: To Flush Or Not To Flush?
Take it to a Trans shop and get a fluid and filter change once a year. Other than that don't worry about it untill it starts slipping and then get a TCI built one to replace it. Flushing is just a waste of fluid however you could put an inline trans filter on the out Lower line to the radiator. Some trans shops recommend it.
Last edited by mmadden55; May 21, 2009 at 11:42 AM.
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From: mocksville nc
Car: '68 corvette '73 Corvette
Engine: 427 454
Transmission: TH400
Re: To Flush Or Not To Flush?
I have always changed the fluid myself. I have a piece of trans. line that I hook to the return line on the cooler. I drain the fluid, and change the filter, then fill the pan with about 2 qts. I cut the car on till i get about 2 qts. in the bucket and repeat till I know it is all new fluid and it turns back to bright red.
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Myself I would do it. 

