diy trans triple flush question
Thread Starter
Melting Slicks
Joined: Apr 2001
Posts: 2,104
Likes: 220
From: Ca.
diy trans triple flush question
I have everything ordered and on the way, but do have a question for anyone that's already done the triple flush. If you have added trans fluid thru the fill hole until it's dribbling out the check hole with the engine running-you plug the check hole-when you shut off the ebgine will fluid come out of the fill hole if you don't put the plug in first before you shut off the engine? Thanks for the help!
Burning Brakes
Joined: Sep 2010
Posts: 931
Likes: 381
Yes, put the level check plug back in before you turn the engine off. If you don't, fluid will come out of the level check hole. You can wait and install the fill plug after the exhaust has cooled.
Last edited by MissileDoc; Mar 24, 2026 at 02:13 PM.
Le Mans Master
Joined: May 1999
Posts: 6,514
Likes: 1,301
From: Windermere FL
You can leave the fill hole open - fluid will not spill out unless you have grossly over filled it.
You must put the plug back in the check hole before you shut off the engine else fluid will come out after you shut off the engine.
What I did is carefully measured the amount I pumped out to match what I added.
You must put the plug back in the check hole before you shut off the engine else fluid will come out after you shut off the engine.
What I did is carefully measured the amount I pumped out to match what I added.
Thread Starter
Melting Slicks
Joined: Apr 2001
Posts: 2,104
Likes: 220
From: Ca.
Thank you for that info! The check hole is easy to get to so no problem closing that up with the engine running. I was afraid that I would have to get the fill hole plug in too and wasn't looking forward to burning myself since it's a tight fit to get to that one. I'll just leave it on the lift untill it cools back off to get the fill hole plug back in.
Thread Starter
Melting Slicks
Joined: Apr 2001
Posts: 2,104
Likes: 220
From: Ca.
I dropped by my local Chevy dealer to ask how much for a triple flush-$1500! So for $300 all in 24 qts filter and gasket I'll be a happy camper. It should go quick with a pump I put together and my quick jack. I upgraded the secondary booster fuel pump in my SC C4 and had a walbro 255l/hr pump leftover, so wired it up and added hoses to pump out and back in.
Thread Starter
Melting Slicks
Joined: Apr 2001
Posts: 2,104
Likes: 220
From: Ca.
Another question on this-I was only getting out 6 qts per flush, not 8qts. even with a pan drop. My old fuel pump died after the 3 flushes, but it only used 18 qts for the three not 24qts. Is that normal? I could always do one more after buying a drill powered pump.
Pro
Joined: Nov 2021
Posts: 513
Likes: 185
From: Pittsburgh, PA
I believe the only way to flush it properly is at the dealer. They have the special equipment to do it. Otherwise you are only changing the fluid in the pan. You need the whole system flushed, tranny, cooler and converter. I had this done on my 2015 Yukon Denali. My wife had someone try dropping the pan, changing the filter and refill and it did not work.
Thread Starter
Melting Slicks
Joined: Apr 2001
Posts: 2,104
Likes: 220
From: Ca.
I believe the only way to flush it properly is at the dealer. They have the special equipment to do it. Otherwise you are only changing the fluid in the pan. You need the whole system flushed, tranny, cooler and converter. I had this done on my 2015 Yukon Denali. My wife had someone try dropping the pan, changing the filter and refill and it did not work.
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Pro
Joined: Nov 2021
Posts: 513
Likes: 185
From: Pittsburgh, PA
Actuqlly it's been stated that there is not enough room on the corvette to attach the lines to the the "official machine". And the dealer does the exact triple flush for the corvette of dropping/draining the pan three times. I did the 3 flush but only used 18 qts and immediatley after the shudder was gone. I will drain and refill with the last 6 qts I already have after I get my drillpowered pump.
Drifting
Joined: Sep 2019
Posts: 1,355
Likes: 635
From: St. Louis
That's crazy... So basically you are diluting the old fluid with new fluid multiple times. Hard to believe that is the only way to flush the system on a Corvette. It seems like the majority of the time when someone has a transmission failure is shortly after they did a transmission flush.
And yes, if you have a transmission that has not had its fluid changed on a regular schedule, doing a flush kicks up all the wear particles that have been sitting quietly in cozy places inside the transmission. Those particles then clog up fine passages and stick control valves and boom! You have yourself a transmission failure!
