ATF Change

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Apr 14, 2006 | 08:34 PM

FussBudget

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Instructor

Joined: Jul 2003

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From: Fairfax, VA

ATF Change

I have a 93 C4. Can one of you smart guys tell me if it is worth it to have my ATF changed with a "pump inlet flush machine? If so, where can I get it done in Northern Virgina? Thanks.
Jim

Apr 14, 2006 | 08:40 PM

Pete K

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I have never done it. The machine usually flushes it through the old, dirty filter. I am a believer in dropping the pan, changing the filter and adding the 4 or 5 qts of fluid.

Apr 14, 2006 | 08:45 PM

FussBudget

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From: Fairfax, VA

There are two types of machines used for flushing. As I understand it, the pump inlet flush machine replaces all the ATF. I believe that they also drop the pan and change the filter.

Apr 14, 2006 | 10:15 PM

Weldmeister

Intermediate

Joined: May 2005

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From: Racine WI

I just had my Trans fluid/filter changed by a GM mechanic (friend of the family) and he explained that by flushing the system you remove all the old fluid (approx 8 qts(?) that normally would be left in the trans. If just dropping the trans cover and changing the filter your only replacing 4 qts.. Trans takes a total of 12 qts I believe. This mechanic felt the best way is by flushing and replacing all fluid with new.

Apr 15, 2006 | 11:37 AM

RAGOVET

Burning Brakes

Joined: Jun 2005

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From: Hyde Park NY

St. Jude Donor '05

Quote:

Originally Posted by Pete K

I have never done it. The machine usually flushes it through the old, dirty filter. I am a believer in dropping the pan, changing the filter and adding the 4 or 5 qts of fluid.

Change the filter too......

Apr 15, 2006 | 01:52 PM

newbecorvetteguy

Melting Slicks

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From: OR

I did mine by removing the top transmission line from the radiator, slipping a length of 5/16 fuel line over the end and ran the other end down to a gallon jug. Started the car and let it idle till the jug was full. Put another gallon in the trans, repeat the process 3 times. The last time, don't put in another gallon. Drop the pan which is now empty, and change the filter and gasket. Rei-nstall the transmission line, put in the last gallon of fluid and it's done. Easy to do and it's got all nice clean fluid now. Just dropping the pan gets less than 1/2 the fluid out. That's ok if you're servicing the transmission kind of early (30k miles, easy driving) all the time. Mine looked and smelled a little toasty so I wanted it all out.

My opinion is just draining what's in the pan is ok if the fluid is still pretty clean anyway. If it's a little burned like mine was, it's better to change it all. If it's really really bad, fluid very dark, smells burned, feels like thicker oil, it's best to leave it alone if you want the trans to keep functioning without having to rebuild it right away. I'm not a transmission guy, it's just my opinion.

Apr 15, 2006 | 08:56 PM

FussBudget

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From: Fairfax, VA

I had a guy just drop the pan, change the filter and replace what drained out with Dexron III. Everything seems just fine. Actually the old AFT looked pretty good. It is about 1/2 inch over filled, but as I understand it, that should not be a problem.

Apr 15, 2006 | 09:00 PM

Pete K

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Quote:

Originally Posted by madmanjim

I would siphon it out. It could become an issue. On a 98 degree day, while climbing a long, high grade, it will heat the fluid and it will rise higher. When idling at operating temp, before taking it for a ride, I aim for the bottom part of the safe zone. XXXXXX. Them it will have room to grow from heat.