Tranny Flush Method - good or bad?

BrandonMc · January 26, 2017, 07:10 PM

I recently saved a Toyota of mine by doing an overly late and very necessary transmission flush.

The method for this is to:
1. Set parking brake, disconnect a transmission cooler line, put it into a bucket.
2. Turn the car on and place in neutral to engage the pump and drain out all the fluid into bucket until it starts to sputter empty.
3. Put in park, shut engine off, reconnect tranny cooler line.
4. Turn engine on, place in neutral, and start re-filling the fluid from the dipstick neck.
5. Drive for a few miles through all gears and check to top off.

Here's a video actually where I learned this method.

Does anyone see a problem with this method on a 454 Chevy Transmission? Worked very well for a Toyota Truck.

tmsnyder · January 30, 2017, 07:40 AM

I don't want to be a nay-sayer but man that seems like an aggressive way to do it. Hey if it works for you go for it.

I tend to just drop the pan and change the filter. It's not getting it all but after 2 or 3 changes it gets most of it.

brians1969 · January 30, 2017, 11:47 AM

My concern would be internal transmission parts moving without the benefit of fluid.

Think of getting a blood transfusion that way.....

Surfinhurf · January 30, 2017, 12:12 PM

I have done this on the Chevy T400 trans in my Winnie.
I have someone on the top side pouring in new fluid at the same time.
When I have drained/refilled 90% of the volume, I quit
Like a blood transfusion, the tranny is never starved for fluid.

Good Luck

HURF

turbinebronze · January 30, 2017, 12:58 PM

I would be very careful doing this. Trans fluid is a high detergent fluid. We have seen transmissions fail shortly after doing this procedure. Particles break loose in the trans that have been sitting from those detergents and move into places they should not be.
You are better served by dropping the trans pan and filter, and refilling. Drive the vehicle a few hundred miles to do a "soft clean", and drop the pan again.
I use to suck out the fluid thru the dipstick tube with a hand pump and refill at every oil change. This kept the trans fluid fresh and did the soft clean also. I would be changing only a few quarts of fluid at a time.
Just my 2 cents, Craig

CapnDirk · January 30, 2017, 05:00 PM

Unlike the oil pan and filter (pull the plug and swap the filter, you got it all) the problem with the trans is the great amount of fluid that is stuck in the converter. Some manufacturers got smart and put a plug in the converter and an access plug in the bottom of the bell housing to drain the converter to. The first time I came across this I thought "smart people" . Later I was working on some Ford that had a damaged radiator in a collision and I needed to top off the trany. Looked and looked could not find the trans dipstick. Finally a call to Ford resulted in "they don't have a dipstick, it's a sealed system"

"So how do I put transmission fluid in it?" "You take it to the dealer"

So, you can get a siphon jug at auto part stores (looks like a weed sprayer) used to get the oil out of boats since the drain plug of the engine is just over the bilge, it feeds down the dipstick tube. Suck the trans dry, refill, run a few hundred miles and do again. At that point you got most of it all. First time of course drop the pan to change the filter, clean the magnet and pan. Unless you found one whole lot of junk in the pan the first time, I don't think you have to drop it the second time.

IMO! I think this is a reasonable, safe, and pretty effective way to go in light of the fact that the trans system is used to going a lot longer than your engine.

cosmic · January 30, 2017, 06:56 PM

I am with craig ... 100% and most especially if it already has that burn smell...
I put a half bottle of ac delco transmition conditioner in every spring and under no circumstances put anything else in a tranny ever....(told to me from my retired transition guy who owed his own shop for 38 years)
The conditioner will freshen up that old fluid.
I remember a few years back telling this to someone and had people tell me I was wrong. I have since put another 15000 miles on my tranny and I have a new one in the garage.. but the old one is still working just fine. Those who know me also no that I use my rig and also travel great distances in it every year...
my 2 cents

hawkaleuge · January 31, 2017, 10:40 AM

Probably as important as changing fluid and filter is adjusting the bands on the 727. I do 20,000 oil and filter change by dropping the pan and while the pan is off I adjust the bands. They always need a little adjustment.
Ed L.

BrandonMc · January 31, 2017, 11:38 AM

Thanks for your replies everyone! Well, I took the radiator off yesterday, and found the fluid in it to be particularly red and looking fresh. Although the transmission does clunk a little while shifting which made me think it would be older fluid. So I guess it's okay but keeping an eye on it.

By allowing the transmission pump to pump that old fluid out in neutral means there's no gearing or other shifting taking place. Meaning this flush method works particularly well. And that's only if my understanding of how it all works is correcxt, which I could most definitely be incorrect. Hm?

Quote from: hawkaleuge on January 31, 2017, 10:40 AM
Probably as important as changing fluid and filter is adjusting the bands on the 727. I do 20,000 oil and filter change by dropping the pan and while the pan is off I adjust the bands. They always need a little adjustment.
Ed L.

Bands, huh? Well last time i dropped the pan and changed the filter a 1000 miles ago, I had no idea there are bands to adjust in there..

tmsnyder · January 31, 2017, 01:21 PM

No bands on your TH400 to adjust that I know of, he's talking on a 727 which is a dodge tranny I believe.

Check out your U-joints if you are getting clunking, there's probably about 3 of them going between the tranny and the rear differential. Make sure you are well chocked if you pull it to thoroughly check it though b/c that's a good way to get killed if you pull the driveshaft w/o chocking.

BrandonMc · January 31, 2017, 07:40 PM

Quote from: tmsnyder on January 31, 2017, 01:21 PM
No bands on your TH400 to adjust that I know of, he's talking on a 727 which is a dodge tranny I believe.

Check out your U-joints if you are getting clunking, there's probably about 3 of them going between the tranny and the rear differential. Make sure you are well chocked if you pull it to thoroughly check it though b/c that's a good way to get killed if you pull the driveshaft w/o chocking.

I'll give that a try thanks. Ad thanks for the kind tip. Perhaps those 6 dollar solid rubber chocks at Harbor Freight are looking nice!

bluebird · February 05, 2017, 10:54 AM

Quote from: BrandonMc on January 31, 2017, 07:40 PM

I'll give that a try thanks. Ad thanks for the kind tip. Perhaps those 6 dollar solid rubber chocks at Harbor Freight are looking nice!

I wouldn't trust any chocks made of rubber or plastic for a MH. Maybe a solid chunk of wood or metal. I made my chocks from an old tree with my chainsaw.