To flush or not to flush?

ProbablyBroke

ProbablyBroke

does not torque to spec
Joined
Nov 7, 2012
Location
Reidsville
To flush or not to flush...That is the question; Automatic transmissions that is. I have a 1991.5 dodge d350 that I'm going through to get ready for dd duty. I believe it has the a518 automatic with overdrive. I am resealing a few systems and changing fluids and intend to drop the pan of the transmission and change the filter/fluid.

I have a friend with a transmission flushing machine. He runs a lube spot. I asked him about flushing the trans, and he said unless it's slipping or shifting hard, don't bother. I would risk dislodging gunk that's found a happy place and gaining trans issues. I'm already set on changing the trans fluid for peace of mind, as well as knowing a. What fluid is in there and b. That my filter and levels are correct.

Opinions on these sort of trans flushes?
Worth the risk? First hand experience of everything going to hell in a handbasket following any trans flush?

Currently my trans shifts as it should and that allows me to sleep at night. I have flushed fluids before in my 7.3 with the e4od, but that was into a bucket under the power of the transmissions pump itself.
 
I'm with your buddy. I think a simple pan drop, filter, and some fresh fluid would be good enough. Although, if memory serves me, they only drop 4 or 5 qts with a pan drop on the Dodge transmissions...kinda disappointing. At least that's what my buddy's 47RE took.
 
I support dropping pan and changing filter. Residue in pan is a good evaluation of trans condition. A little grey sludge is normal. Lots of metal not good. Fluid should not smell burnt.
 
Not to sound like an echo but:

Jody Treadway said:
IMO- drop the pan, adjust the bands, replace fluid and filter and adjust the TV cable.
Click to expand...

Never been a fan of power flushing, usually just drain and refill. If the fluid is still nasty after that just repeat until it's clean.
 
So do I :D
 
You did not mention the mileage, but it's my understanding that flushing an older transmission with high miles is not a good idea. I would not do it.

Another question... most rebuild shops say to leave the bands alone... do not adjust them, ever. The truck forums, etc. say it is a must to periodically adjust the bands. I have a written procedure for doing it, but due to mixed info I am afraid to do it. Anyone have any factual experience with this?
 
Granny said:
You did not mention the mileage, but it's my understanding that flushing an older transmission with high miles is not a good idea. I would not do it.

Another question... most rebuild shops say to leave the bands alone... do not adjust them, ever. The truck forums, etc. say it is a must to periodically adjust the bands. I have a written procedure for doing it, but due to mixed info I am afraid to do it. Anyone have any factual experience with this?
Click to expand...

a_kelley said:
If you have to adjust the band, likely it's worn out.. probably why trans shops say don't.
Click to expand...


Regarding getting adjusting the bands...like most things in life I choose to find an expert an follow their advise.

Oh lookie here we have a dodge transmission expert:


Jody Treadway said:
I've been into a lot of them post-flush when I was the dealer.
IMO- drop the pan, adjust the bands, replace fluid and filter and adjust the TV cable.
She'll shift like butter assuming there aren't any failed hard parts inside the trans.
Click to expand...
 
BTW just playing, love yall
 
@Ron

"Assuming there aren't any failed hard parts.."

Band wear/stretch would be negligible, from what I have seen, without failure.. open to correction but I've rebuilt a couple.. bands aren't made of much, sheet metal and a thin coat of friction material.

But since you got it apart, it doesn't hurt to bring it back to spec, but I'd bet it's within spec when it is being adjusted. ;-)
 
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