Transmission Flush not recommended for 850's

[polskamafia mjl]

FYI, the DIY replacement here on MVS is called a Drain and Fill. A flush is a flush and is completely different from the drain and fill.

[Jasle]

Hmmm. I worked my way through college at an auto shop. I've done tons of "Power Flushes" and rebuilt transmissions both auto and manual. What I have read is sounding like its not based on fact. 1st...When synthetic oils first came out they did have problems eating seals...No longer a problem. Not even a problem in the last 10 years. 2nd a "Power Flush" is a misnomer. The only reason for the "Power" in the "Power" flush is for a small pump to fill the trans with oil. You remove the line going to the cooler and plumb it to the capture tank. This empties the crappy fluid into the tank. The "Powered" pump, which is a lower pressure pump, simply fills the line with clean fluid you have put in its reservoir. It in no way breaks the filter, welds, or anything else related to the trans.
Nothing exchanges the fluid as completely as the flush machine which I refuse to call power flush. Try this. Fill a cup with water. Then drop some metal shavings and dirty oil in it. Dump out half and refill with clean water. Would you drink it? Sure it will taste better than if you did not swap half...but dirty water is dirty water. Just as dirty fluid is dirty fluid. I have 202K on my V70...I perform all my maintenance...except paying someone $79 to flush my fluid at 50k miles only because I don't have a machine at home.
I now work on particle accelerators. I wish the maintenance was as straight forward as a transmission flush. And oh by the way...that brake fluid flush they try to sell you...Worth it, just most people don't understand what goes on with a flush...and that is where you really "Power Flush" a system.

[Hoov]

I now work on particle accelerators. I wish the maintenance was as straight forward as a transmission flush. And oh by the way...that brake fluid flush they try to sell you...Worth it, just most people don't understand what goes on with a flush...and that is where you really "Power Flush" a system.[/quote]

Actually, I believe you are somewhat brighter than some of your co-workers.
I don't know which equipment your shop used but the Ford-Mecury shop I worked in had a "flusher" with adjustments as to pressure. We were supposed to look up the the "pressures" but fact is, they were all pretty close so ... ... ...?

Then, there were explicit directions as to how to hook the thing up ... Uh-huh ... & I know EVERYBODY (all 29 of us) followed those directions to the letter even though three 1989 ford vehichles were reversed. ...
Damn! Where IS that "Sarchasm" font? ...

You are 100% correct about Brake fluid flushing!! Fact is, I now have a diy one I assembled yesterday from directions I found in a post here that allowed me to use my own air compressor. $8.00 Bucks ... & Easy.

I think your post is 100% on the mark as to the facts but frankly the other facts are that a drain & fill always works well! If some idiot at the shop isn't paying attention, who loses? ... I also think your explanation is the best one I have heard! (This is not the only thread here that discusses this topic.)

I also believe (No facts to back it up) high milage transmissions need a little more consideration. ... I do have a Nissan Pathfinder W/156,000K that I'm venturing into a wilderness area you would not want to WALK into in a few months. Fact is, most folks could NOT walk into. But she will get me there & back. I have no doubt! Drain & fill. Yes! ... Power flush? ... Not even going to happen.

Hoov

[polskamafia mjl]

I have no first hand experience in what happens during a power flush. I have however talked to a mechanic and he himself told me never to flush a high mileage tranny as it will force all of that gunk out that is keeping the seals tight. Good think I'm not drinking my ATF fluid, I suppose. Word of advice, DON'T flush your trannies. The drain and fill method is MORE than adequate.

[Craigd2599]

okay boys but back to my question...what is described here is not a power flush is it? I mean the new fluid is being sucked in at normal operating pressure and in the usual direction of flow. Is this really going to dislodge anything serious? Isn't this really just replacing it by drain and fill except all at once?

[Hoov]

okay boys but back to my question...what is described here is not a power flush is it? I mean the new fluid is being sucked in at normal operating pressure and in the usual direction of flow. Is this really going to dislodge anything serious? Isn't this really just replacing it by drain and fill except all at once?

Confusing huh?
A "drain & fill" is simply removing the trans drain plug & emptying the three or so quarts that run out &. Then you put the the plug back in & replace the same amount of fluid that was drained. You're done!

A drain & "flush", as described here, is the same thing but you don't quit there. You disconect the upper trans coolant hose at the radiator & pump out another 2 quarts or so, stop, refill the amount pumped out. Continue doing this until the fluid runs out clear. This will take a total of 12 or so quarts of new fluid.

There is some controversy about doing the "flush" part & the drain & fill all at once on high milage transmmissions if the fluid has never been changed.
Several folks here believe a "drain & fill" should be done & then the car driven for a couple weeks before doing it again.
I did mine all at once. (164K miles). My trans was functioning well, no leaks & I have had no problems since. My fluid was not all that gunky but it was dark & smelled burnt. I doubt there was or is anything to dislodge.

These transmissions run between 90 & 100lbs of pressure. A power flusher can produce a lot more than that. (seperate machine pump) Personaly I don't think they are a good idea. Others will disagree.

Hoov

[polskamafia mjl]

+1

[Craigd2599]

mine just hit 200,000 miles. Fluid is pink and no unusual odor. Might go ahead and do the "flush" and just make the last quart Lucas trans treatment just for safe measure. I am a big Lucas additive fan.

[Timberwolf530]

okay boys but back to my question...what is described here is not a power flush is it? I mean the new fluid is being sucked in at normal operating pressure and in the usual direction of flow. Is this really going to dislodge anything serious? Isn't this really just replacing it by drain and fill except all at once?

No it isn't a "flush". You are just basically changing all the fluid in the pan, then pumping the new into the TC while simultaneously pumping out old fluid that would normally go back into the pan. So, drain & refill pan with new fluid, pump out 4 qts(that's what the pan holds), turn off the car & refill the pan, pump out 4 qts, turn off the car & refill the pan. Repeat until clean fluid starts coming out the hose, your done. Re-attach the hose and top off the pan. I've never done this procedure on my 850, so I'm not sure what the total capacity of the tranny is, but a good rule of thumb is that the pan usually holds between 1/3-1/2 the total volume of the system. It's perfectly safe because you are not doing anything the transmission doesn't do every time you run the car, except you are acting as a human return hose.

[Craigd2599]

That's what I thought Timber. Didn't seem too likely to upset anything.