Radiator replace turns into plenum...
Captain
Joined: Nov 2010
Posts: 632
Likes: 4
From: SE Tx
No, the reason you shouldn't flush a transmission is because it is typically done with a machine that hooks to the dipstick and reverse flushes the fluid, pulling the fluid in the opposite direction of normal flow. This in turn pulls all the junk trapped in the filter up into the valve body and jams up the internals of the VB.
If a trans needed burnt clutch material to act as a friction modifier to function it would:
1. Slip like a mother when it was new
2. Not use a filter as it just collects all that precious clutch material
3. Not have a magnet sunk in the pan for the reasons stated above.
4. Use a type F or other fluid that already has "the grippy stuff" in it.
Shops back flush for one reason. It saves time. They don't have to drop the pan and change the filter, they just reverse the flow and pull the crap right up the VB.
If a trans needed burnt clutch material to act as a friction modifier to function it would:
1. Slip like a mother when it was new
2. Not use a filter as it just collects all that precious clutch material
3. Not have a magnet sunk in the pan for the reasons stated above.
4. Use a type F or other fluid that already has "the grippy stuff" in it.
Shops back flush for one reason. It saves time. They don't have to drop the pan and change the filter, they just reverse the flow and pull the crap right up the VB.
1. A new tranny doesnt need this modifier because there is enough clutch there for it to engage without added assistance (mine shifted hard and fast for 3 months after my rebuild)
2.The filter traps the larger pieces, but the very fine, particulate matter I am speaking of passes straight through
3.Some of the clutch material is nonmagnetic
4.Chrysler is the sole patent holder of atf+4 and they stand to gain more $$$ from using it exclusively in their trannies. I believe they designed it to use this clutch material as the tranny ages to account for the absence of the "grippy stuff"
Last edited by Mad_Scientist; Jan 29, 2011 at 12:38 AM.
Administrator
Joined: Apr 2010
Posts: 87,461
Likes: 4,218
From: Clayton MI
When I worked at the dealership, if we had a customer come in for a trans service, we would very pointedly ask how long it had been since they had last done one. For those that answered that they didn't know, or, it had been some very long period of time/mileage, it was standard procedure to warn them that the mere act of doing the service may kill their trans. (just changing out filter and whatever fluid was lost in the process) I watched this happen on several transmission. The old crappy fluid worked acceptably well, but, change out the fluid, and the trans was now slipping...... (GM dealership.)
Flushing the trans does indeed circulate all the crap throughout the trans, and cooler, etc. Doing so on an older trans, that hasn't been well maintained, is pretty much a guarantee of trouble. Just not a good idea.
Flushing the trans does indeed circulate all the crap throughout the trans, and cooler, etc. Doing so on an older trans, that hasn't been well maintained, is pretty much a guarantee of trouble. Just not a good idea.
Legend
Joined: Jul 2007
Posts: 7,843
Likes: 13
From: DFW, Texas
My understanding of a poorly maintained trans was that the new fluid with its replenished detergent package will loosen deposits and collections of debris and send them flying thru the lines, much like a blood clot thru an artery.
Administrator
Joined: Apr 2010
Posts: 87,461
Likes: 4,218
From: Clayton MI
True. But, much like the human body, there are many possible failure modes that flushing can induce. It is simply a bad idea in general. Unless it is something done on a regular basis anyway. (but, I really don't see any benefit in that.....)
Legend
Joined: Jul 2007
Posts: 7,843
Likes: 13
From: DFW, Texas
My understanding of a poorly maintained trans was that the new fluid with its replenished detergent package will loosen deposits and collections of debris and send them flying thru the lines, much like a blood clot thru an artery.
Administrator
Joined: Apr 2010
Posts: 87,461
Likes: 4,218
From: Clayton MI
It is seriously a crap shoot.
