Best method for full transmission flush?

[Jimbo052]

I am looking for a way to exchange all the fluid in my transmission including the fluid in the transmission cooler. I've looked around here as well as the old site for a technique that covers all the bases but with no success. This is what I'm looking for:

1. Minimal fluid and equipment cost.
2. Exchange as much fluid as possible.
3. Pan drop with filter change.

I know the professional machines pump new fluid through the entire system until the fluid is clean. It also seems that a commonly used DIY method is to disconnect the line at the cooler and let the transmission pump the dirty fluid out, but this method misses the transmission cooler and the line back to the transmission. Does anyone have any ideas or tricks they use? Thanks!

 

[Jimbo052]

So far I've found these which may or may not be useful:

First of all, the transmission cooler flush looks like this:
View attachment 19342
and can be found here.

A transfer pump may also be useful:
View attachment 19343
and can be found here.

Finally, as pointed out in another post, this fitting can be used to attach to the transmission cooler:
View attachment 19344
and can be found here.

I'm just throwing these out there to see if they spark any ideas.

 

[RedEnvoyDenali]

You will find several opinions on how to do this.

I have used the Gerotor pump to extract fluid at the input to the tranny cooler (passenger side of radiator). I used a labeled bucket to keep track of the volume of oil withdrawn. I don't think the fluid volume you would leave in the In Radiator Cooler and return line would be enough to worry about,so I don't. I also advise to change the fluid in the pan and filter each time you change the fluid. You also want to clean the magnet in the pan, again each and every time. I also advise installing a drain plug in the pan to make draining the pan easier.

Some folks don't recommend use the Gerotor pump for this, as you run it with very little or no oil for a short period of time. I don't think you hurt it since the time is short and with the engine at idle you aren't putting any stress on the parts. "Just my opinion".

I am a firm believer in changing the tranny fluid regularly (something less than every 10 years or so depending up mileage) and adding a tranny cooler even if you don't tow anything. Heat kills transmissions and a cooler will assist in keeping the transmission from overheating. Transmissions generate their own heat at an amazing rate. I have posted a chart several times showing the tranny life compared to the running temps.

Transmission temperature/failure chart.

This is simple, if not somewhat messy job (the first time) but an afternoon spent in the garage every couple of years or so should save the transmission from turning into a grenade.

 

[MAY03LT]

I know the professional machines pump new fluid through the entire system until the fluid is clean.

Every fancy trans flush machine that I have used uses the trans pump to do the pumping part. You unhook either one of the cooler lines at the cooler and put one hose from the machine to the cooler line and another hose to the cooler (it has the adapters). The point of that was, doing the 2 bucket method will do the exact same thing that the fancy one will, including flushing the cooler. The machine has a 14 qt capacity and that's about what it takes to get it all flushed in 99% of vehicles, including ours.

 

[Mark20]

So you fill one - clean - bucket with the new fluid and let the other collect the old? Is the Gerotor pump strong enough to pull from the new fluid bucket?

 

[Jimbo052]

Can we use the transmission to suck new fluid from a bucket while pumping the old fluid into another bucket? The tube from the bucket to the cooler would have to be primed with fluid, right? I guess it could be started with a hand pump and then it would function like one of the professional machines.
View attachment 19351
Sorry for the bad artwork.

 

[Jimbo052]

So you fill one - clean - bucket with the new fluid and let the other collect the old? Is the Gerotor pump strong enough to pull from the new fluid bucket?

This is a good point. The bucket with new fluid should probably be elevated and if it was elevated enough, gravity could prime the tube.

 

[RedEnvoyDenali]

This is a good point. The bucket with new fluid should probably be elevated and if it was elevated enough, gravity could prime the tube.

If you aren't concerned about the waste factor this should probably work. The only problem I would see would be the 5 quarts in the pan and the large amount in the torque converter (I think about 5-7 quarts). With so much old fluid mixing with the new you might have to pump 20 quarts or more, through instead of the required 12 just to get the old fluid out. Even with the previous method of just disconnect and drain there still is a couple of quart overlap and it takes a bit to change the color from brown to red.

 

[Jimbo052]

So I was thinking about doing it this way:

1. Disconnect the return line at the cooler. (Where the fluid leaves the cooler)
2. Attach a clear tube to the cooler using the adapter pictured earlier in this thread. Place the end of the tube in a 5 gallon bucket.
3. Put on the parking brake, put the transmission in neutral, start the engine, and finally put the vehicle in drive. Shut the engine down when the fluid coming out of the hose starts to sputter. Return to neutral.
4. Drop the pan, change the filter, and clean the pan/magnet.
5. Install a drain plug in the pan. (Optional)
6. Re-install the pan with a new gasket.
7. Fill the transmission to approximately the correct level.
8. Find a buddy. Have your buddy start the engine and put the transmission in drive. Pour new fluid into the dipstick at about the same rate it is being pumped into the bucket. Tell your buddy to shut the engine off when the fluid coming out of the hose is clean.
9. Remove the tube and re-install the return line on the cooler.
10. Add fluid to the transmission as you normally would to get it to the proper level.
11. Done

I wrote that the transmission should be in drive while pumping the fluid out because I have heard that fluid is only pumped through the torque converter in either drive or neutral in many vehicles. Can someone with specific knowledge of our transmissions confirm or debunk this? Using this procedure will pump fluid through the cooler before expelling it into the bucket. What do you guys think?

 

[Sparky]

I did those steps for the most part. The differences was at the end I didn't do #8. But I don't think it was necessary because 1) After it sputtered and I shut it down, there was very little fluid in the bottom of the pan and 2) I put in at least 11 quarts of trans fluid when I filled it back up.

At the same time however, I was doing a cooler line replacement (fancy that) and also installed a Transgo kit in the transmission, so it was open and dripping for a lot longer than just a normal fluid change. Removing the extra stuff for the Transgo kit also let out a little more fluid from various accumulators and such as well.

 

[groundshock]

JMO, but I'd just pay the money and get it done right.

Buckets? Adapters? Buddies? Sounds like a recipe for disaster to me.

 

[Sparky]

I don't know, I wouldn't trust a shop in general to do it right. My brother is not a car guy but he asked the one place he was at about dropping the pan, changing fluid, etc. They told him that they do a flush to get the most of the old fluid out vs just a pan drop. Ok... so he commented that of course they still drop the pan to replace the filter. Oh no they said, they BACKFLUSH and that knocks everything off the filter so it doesn't need replaced. Um, WHAT? Where does all that crap go? Some gets lodged in various places in the transmission I'm sure

Maybe I'm paranoid, but I'd rather do it myself for something relatively simple and know nothing funny went on in the garage while I wasn't looking Similar reason why I don't have my oil changed anywhere, I don't trust the jiffy lube type shops (that, and I'm particular about the oil I use).

 

[lint]

Can we use the transmission to suck new fluid from a bucket while pumping the old fluid into another bucket? The tube from the bucket to the cooler would have to be primed with fluid, right? I guess it could be started with a hand pump and then it would function like one of the professional machines.
View attachment 4685
Sorry for the bad artwork.

some guy had pics up on trailvoy awhile back ,the same way but he cut a hole on the side at the bottom of the bucket with the new fluid in and put a off and on flow value .and hooked his hose up to it and elevated it. so it would just poor out of the bucket and in to the trannie. as the old came out. I dont remember if he had it hooked in the same place or put the hose dont the fill tube.

 

[Mark20]

If you have a homebrew beer and wine making shop near you, pick up a bottling bucket. Five gallon pail with a valved spigot on it. Perfect for this kind of job.

 

[Mooseman]

I basically used the method from the OS, which didn't mention anything about putting it in drive. Just running it in park still pumped the fluid. Basically the same method as explained here except skip no.3 and the part of no.8 to put it in drive. Just start the engine and the pump will pump. In fact, you would not want it in drive if you are draining it out now do you?

My fluid was a funky brown and it came out nice and pink after. No issues with it since.

 

[Sparky]

VERY good point. You don't want anything actually moving inside except the pump when pumping it dry.

 

[Jimbo052]

I was just thinking...I hate using perfectly good (and expensive) fluid to do the flush. Considering the oil in my trashy is currently conventional Dexron III, couldn't I just use a cheap oil to do the flush and then full up with the good stuff?

I was eyeing this up: http://www.amazon.com/gp/product/B0026L2M0C/?tag=gmtnation-20

 

[gmcman]

I removed the line from the passenger side cooler but when I do it again, I will get the Hayden 397 fitting so I can tap the drivers side of the trans cooler in order to flush it out.

Hayden Automotive 397 - Hayden Transmission Line Adapter Fittings - Overview - SummitRacing.com

1. Purchase the fitting
2. Purchase 4 gallons of some quality ATF, Amsoil, Mobil 1, Valvoline Maxlife, or whatever you choose...just get Dex 6.
3. Pull the driver's side trans cooler line from the radiator and push the fitting into the radiator, run a hose from the fitting to a 5 gal bucket. Easier to raise the vehicle on jack stands or use a lift.
4. Start the engine and run it until the flow sputters.
5. Pull the pan and change the filter, reinstall pan then refill about 1 gallon into the dipstick tube.
6. When tightening the bolts on the trans pan, use a torque wrench and tighten to 100 INCH POUNDS. Start at about half that on the first pass then set it for 100. You need to go around the pan 3-4 times with the torque wrench with the same setting to get the bolts torqued....each subsequent pass will compress the gasket more and more until the bolts no longer turn at the desired setting.
7. Start engine again and run until it sputters.
8. Refill with another gallon and run until it sputters.
9. Reattach the cooler line
10. Use the last gallon to top off the fluid
11. Check the trans level with engine idling and in park and set to FULL COLD. Drive about 5-10 miles or so and then ensure the fluid level is FULL HOT.

 

[Mooseman]

I was just thinking...I hate using perfectly good (and expensive) fluid to do the flush. Considering the oil in my trashy is currently conventional Dexron III, couldn't I just use a cheap oil to do the flush and then full up with the good stuff?

I was eyeing this up: Peak Performance PDT007 Dexron III/Mercon Automatic Transmission Fluid - 1 Quart, Pack of 12:Amazon:Automotive

Why mix? You would dilute the benefits of the DexVI with the DexIII. A fair amount will stay in the torque converter despite the flush.

 

[deekster_caddy]

Personally I advise against flushing. I've had more people report issues after a transmission flush than I'd care to talk about. Maybe this platform is more robust, but still - I have a really bad taste for flushes.

I advise people to a drain plug to the pan (about $5) and change the pan fluid every time you change your engine oil, and every other year doing a pan drop/filter change. The drain plug makes this possible - no need to drop the pan and what's a few more bucks worth of fluid into your baby anyway? (more frequently if you are a high mile driver of course) This works well if you use synthetic oil and go longer intervals on engine oil changes. Otherwise you could do every other oil change...

Transmission fluid is one of the most underserviced fluids on the road, IMO. Take care of the fluid changes and a flush won't be necessary.

 

[Mooseman]

That's like saying "my engine oil hasn't been changed in a long time so I'll just replace a third of it". More than likely, if a tranny dies after a flush, it would have died no matter what you do because it was so badly neglected and/or abused. Or the misconception comes from lube places with their flushes where they don't drop the pan and replace the filter, and likely with cheap DexIII instead of DexVI.

My truck was badly neglected by the previous owner and the tranny fluid was a skanky brown. I flushed the tranny last July using the method above, no problems at all.

 

[Sparky]

Also I think depends on what you mean by "flush."

If by flush you mean "attach a pump and force fluid backwards through the system maybe at increased pressure" which is what some places do, then yeah that could cause some issues by knocking stuff back off the filter and running it through the system to get caught in places it shouldn't be.

I don't think a forward flush at normal pressures and then a proper filter removal should damage a thing.

My brother's old beat 95 taurus is a great example of a car that needed a proper flush to even shift properly again. It's been fine since the flush.

 

[deekster_caddy]

That's like saying "my engine oil hasn't been changed in a long time so I'll just replace a third of it".

Yes, but if you change the fluid by dropping the pan like the service manual says, you really are only replacing a third of it. Most of the old fluid stays in the converter. I'm just suggesting to do it more frequently by making it easier to do.

 

[deekster_caddy]

There are also Chemical Flushes that use a cleaning agent in addition to the machine that exchanges the fluids.

There is a LOT of heresay in this topic, because there are so many different possible methods to use, and when people refer to the 'flush' they had done rarely are they talking about the same thing.

If you aren't having a problem, the "frequent 1/3 of your fluid at a time" change method works very well and has never caused a problem that I'm aware of. That's why I recommend it. Changing out all of the fluid at once HAS caused problems for some people, but was their transmission in trouble before that happened? I don't know and neither do they.

 

[davenay67]

There are also Chemical Flushes that use a cleaning agent in addition to the machine that exchanges the fluids.

There is a LOT of heresay in this topic, because there are so many different possible methods to use, and when people refer to the 'flush' they had done rarely are they talking about the same thing.

If you aren't having a problem, the "frequent 1/3 of your fluid at a time" change method works very well and has never caused a problem that I'm aware of. That's why I recommend it. Changing out all of the fluid at once HAS caused problems for some people, but was their transmission in trouble before that happened? I don't know and neither do they.

I am planning on installing a transmission drain plug on my next pan drop. That way I can do somewhat regular drain / refills, the regularity of replacing 1/3 capacity will keep the fluid in pretty decent overall condition. Simply drop the pan and replace the filter every 30,000 miles or so. If the tranny is in decent condition then this regime should keep it alive for the duration of the vehicle's life.

Whicever way you change the ATF, it will be better than ignoring the tranny and never / rarely ever changing ATF..!!