Im planning on flushing my transmission through my cooler lines. I have a 94 gmc sierra, the return line is on the left side top of my radiator correct? and also do i pour new fluid in while im running my trucks old out? or wait till it stops flowing and turn off truck then refill? seems better to pour in while draining so nothing is empty.. im about to do the auto rx treatment... any advice would be swell!!! thanks
flushing transmission
- Thread starter johnnyrandal
- Start date
- Status
Find a clear/translucent container...I use an old washer fluid bottle...measure 2 QTS, make a mark on the side. Connect a hose from the cooler line that drains into your container.
If possible, start by draining the pan (even if you don't or can't this still works) and refilling with fresh fluid.
Start the engine, idle it until 2 Qts are pumped out. shut off the engine, add 2 Qts.
Repeat until clear...
If possible, start by draining the pan (even if you don't or can't this still works) and refilling with fresh fluid.
Start the engine, idle it until 2 Qts are pumped out. shut off the engine, add 2 Qts.
Repeat until clear...
Last edited:
If you run it till it sputters, you will introduce air bubbles. The 2qt method is usually pretty safe. If you can do a standard drain/fill first, it will help. I have even hear of people overiflling by 1 qt so that they can force 3qts out each on/off sequence.
Drop the pan and clean it , replace the filter with new. you can keep on adding fluid with the engine running. The fluid coming from the cooler lines is the oil directly from the torque converter. years ago the torque converters would have drain plugs.
Much easier method. Get a mity vac or a johnson evinrude lower unit fluid pump. put a length of 3/8 clear hose on it. drop it down the dip stick hole. pump out 3-5 quarts. Then do the pan drop and filter change. Put the pan back on and refill the trans. Now do the 2 quart method. Much less mess.I use my mity vac for brakes , vacuum checks, fluid exchanges like ps pumps trans and gear oil.
How do you clean the mityvac once you have used it on fluids?
Do some shopping around for a good price using a BG fliud exchange machine. They are all over the place. Lot less mess, disposal plus a better job.
Last edited:
If you pump a little water through it and let her dry and blow out the hoses with compressed air it works fine. If i am doing different oils the same day just keep pumping the fresh fluid then change to the newer one pump till it fills up with the new fluid. . .I have used it only on trans, ps ,and brake, fluid so far. When it dries it works fine on vacuum again.
No contamination of fluid if that is what u mean.
No contamination of fluid if that is what u mean.
The dealership repair manual method for draining most transmissions is to unplug the return line, run the engine in park or neutral (whichever the transmission pumps in) until it stops pumping out liquid and then turn it off. By stops pumping out, I mean slows to a crawl, it's a noticeable difference when it hits this point. When you reach this point you drop the pan or release the drain plug. Then add however many quarts you pumped out back into the transmission and run it in park or neutral again until it stops pumping. Then fill the transmission to the proper amount as per the owners manual. This generally means running it until it's operating temperature and checking the dipstick, some require you to idle it in park or neutral (whichever it pumps in).
This uses ~10 quarts for my 8.66 quart transmission sump and should be a 100% exchange of ATF.
I say most because I have not serviced a car where this wasn't the preferred non-machine method, but I am sure they exist.
This uses ~10 quarts for my 8.66 quart transmission sump and should be a 100% exchange of ATF.
I say most because I have not serviced a car where this wasn't the preferred non-machine method, but I am sure they exist.
Popular Mechanics - Directions for doing a transmission flush. Ask here and you'll get different answers about running until the cooler line spit air. Some say run until it spits, others (my preference) like to do 2 or 3 quarts and refill through the dipstick hole. Looking above, most prefer to not take the chance running the pump dry.
http://www.popularmechanics.com/cars/how-to/maintenance/1272521
http://www.popularmechanics.com/cars/how-to/maintenance/1272521
Last time I did mine, I would let it pump out about 3 quarts, and then refill.
Originally Posted By: Letter_K
Popular Mechanics - Directions for doing a transmission flush. Ask here and you'll get different answers about running until the cooler line spit air. Some say run until it spits, others (my preference) like to do 2 or 3 quarts and refill through the dipstick hole. Looking above, most prefer to not take the chance running the pump dry.
http://www.popularmechanics.com/cars/how-to/maintenance/1272521
Can someone explain to me how running the pump until it stops pushing liquid is damaging to the transmission. I really don't understand this concept but it's reiterated very often on various forums. A link to an article on the damaging effects of this would be really appreciated.
And your link says: "Many professionals enhance this procedure by pouring a few quarts of fresh fluid into the dipstick tube at roughly the same rate that the old fluid is coming out, thus adding flushing action."
Sure that's fine and good, it's going to suck up any fluid in the pan that's above the level of the pump. It's basically faster than the service manual way but less fluid use conscious. However, it doesn't say how it's damaging to the transmission to run it until it pumps air. I really am thoroughly ignorant to how the pumping air damages the transmission.
Popular Mechanics - Directions for doing a transmission flush. Ask here and you'll get different answers about running until the cooler line spit air. Some say run until it spits, others (my preference) like to do 2 or 3 quarts and refill through the dipstick hole. Looking above, most prefer to not take the chance running the pump dry.
http://www.popularmechanics.com/cars/how-to/maintenance/1272521
Can someone explain to me how running the pump until it stops pushing liquid is damaging to the transmission. I really don't understand this concept but it's reiterated very often on various forums. A link to an article on the damaging effects of this would be really appreciated.
And your link says: "Many professionals enhance this procedure by pouring a few quarts of fresh fluid into the dipstick tube at roughly the same rate that the old fluid is coming out, thus adding flushing action."
Sure that's fine and good, it's going to suck up any fluid in the pan that's above the level of the pump. It's basically faster than the service manual way but less fluid use conscious. However, it doesn't say how it's damaging to the transmission to run it until it pumps air. I really am thoroughly ignorant to how the pumping air damages the transmission.
I don't see how it would do damage either, but avoiding the possibility never hurts.
Originally Posted By: rslifkin
I don't see how it would do damage either, but avoiding the possibility never hurts.
That's entirely valid. My problem really is not with the different method, they both work; it's that I have heard that scenario over and over again on various forums and most people claim it damages the transmission to not refill after pumping a quart or two.
I find my car shifts seamlessly with the "boutique" ATF so I try and minimize my losses as much as possible to avoid spending a small fortune in ATF. Of course if it does damage the transmission then it's obviously not worth it to cheap out.
I don't see how it would do damage either, but avoiding the possibility never hurts.
That's entirely valid. My problem really is not with the different method, they both work; it's that I have heard that scenario over and over again on various forums and most people claim it damages the transmission to not refill after pumping a quart or two.
I find my car shifts seamlessly with the "boutique" ATF so I try and minimize my losses as much as possible to avoid spending a small fortune in ATF. Of course if it does damage the transmission then it's obviously not worth it to cheap out.
I guess one could not fill a clean bucket with the proper amount of fresh fluid and allow the transmission to pull in the fluid from the return line while the output line is depositing old fluid in another bucket?
What about if the clean bucket was significantly higher than the transmission?
What about if the clean bucket was significantly higher than the transmission?
I've never been able to pour new fluid down the skinny dipstick tube as fast as it was pumping out.
There is no suction pump. It won't pull the fluid in. And gravity flow through the skinny return line will be slooooow.
Pan drain & refill, then two quarts out/engine off/two quarts in works well. A mechanic might just let the engine keep running and squeeze the cooler line with vice-grips...my nephew, a mechanic, told me about that...but I wouldn't do it.
There is no suction pump. It won't pull the fluid in. And gravity flow through the skinny return line will be slooooow.
Pan drain & refill, then two quarts out/engine off/two quarts in works well. A mechanic might just let the engine keep running and squeeze the cooler line with vice-grips...my nephew, a mechanic, told me about that...but I wouldn't do it.
Originally Posted By: cmf
Originally Posted By: Letter_K
Popular Mechanics - Directions for doing a transmission flush. Ask here and you'll get different answers about running until the cooler line spit air. Some say run until it spits, others (my preference) like to do 2 or 3 quarts and refill through the dipstick hole. Looking above, most prefer to not take the chance running the pump dry.
http://www.popularmechanics.com/cars/how-to/maintenance/1272521
Can someone explain to me how running the pump until it stops pushing liquid is damaging to the transmission. I really don't understand this concept but it's reiterated very often on various forums. A link to an article on the damaging effects of this would be really appreciated.
And your link says: "Many professionals enhance this procedure by pouring a few quarts of fresh fluid into the dipstick tube at roughly the same rate that the old fluid is coming out, thus adding flushing action."
Sure that's fine and good, it's going to suck up any fluid in the pan that's above the level of the pump. It's basically faster than the service manual way but less fluid use conscious. However, it doesn't say how it's damaging to the transmission to run it until it pumps air. I really am thoroughly ignorant to how the pumping air damages the transmission.
I never said running dry would hurt the pump. My preference is better safe then sorry, but that is just my preference. I'm guessing the real reason why is that most see the fluid keeps the pump cool and lubricated.
Running dry and shutting off right away probably doestn't do harm and probably cuts the refills in half.
Why do we do what we do? Someone else gave a good reason and we said that sounds plausible. Look with a critical mind and you'll see it throughout BITOG and internet forums. Why is Pennzoil so popular here? It has factory cleaning power - why, because it was posted over and over again and Pennzoil marketing told us so. Same with Auto RX and many other products.
Some things get repeated so much they become gospel. There is probably a bit truth and a bit fiction in these ideas.
It's the same with stock tips. Why do people trust a hot tip from a stranger?
OK, I'll stop being a philosopher now.
Originally Posted By: Letter_K
Popular Mechanics - Directions for doing a transmission flush. Ask here and you'll get different answers about running until the cooler line spit air. Some say run until it spits, others (my preference) like to do 2 or 3 quarts and refill through the dipstick hole. Looking above, most prefer to not take the chance running the pump dry.
http://www.popularmechanics.com/cars/how-to/maintenance/1272521
Can someone explain to me how running the pump until it stops pushing liquid is damaging to the transmission. I really don't understand this concept but it's reiterated very often on various forums. A link to an article on the damaging effects of this would be really appreciated.
And your link says: "Many professionals enhance this procedure by pouring a few quarts of fresh fluid into the dipstick tube at roughly the same rate that the old fluid is coming out, thus adding flushing action."
Sure that's fine and good, it's going to suck up any fluid in the pan that's above the level of the pump. It's basically faster than the service manual way but less fluid use conscious. However, it doesn't say how it's damaging to the transmission to run it until it pumps air. I really am thoroughly ignorant to how the pumping air damages the transmission.
I never said running dry would hurt the pump. My preference is better safe then sorry, but that is just my preference. I'm guessing the real reason why is that most see the fluid keeps the pump cool and lubricated.
Running dry and shutting off right away probably doestn't do harm and probably cuts the refills in half.
Why do we do what we do? Someone else gave a good reason and we said that sounds plausible. Look with a critical mind and you'll see it throughout BITOG and internet forums. Why is Pennzoil so popular here? It has factory cleaning power - why, because it was posted over and over again and Pennzoil marketing told us so. Same with Auto RX and many other products.
Some things get repeated so much they become gospel. There is probably a bit truth and a bit fiction in these ideas.
It's the same with stock tips. Why do people trust a hot tip from a stranger?
OK, I'll stop being a philosopher now.
Last edited:
Running dry most definitely carries a chance of RUINING the trans pump! Absolutely, positively!
Just like running the engine with no oil in the crankcase, except that transmission fluid is not nearly as good a lubricant, so things get buggered up quicker.
If you watch the exit line and shut the car off the second you see air you are extremely unlikely to damage anything.
Just like running the engine with no oil in the crankcase, except that transmission fluid is not nearly as good a lubricant, so things get buggered up quicker.
If you watch the exit line and shut the car off the second you see air you are extremely unlikely to damage anything.
The method I was presenting is not something I randomly came up with, it's the method that the service manual for my car and every car I have worked on uses. These service manuals are made by the manufacturer of the automobiles, not me. I really have no interest in the success or failure of the method, beyond my own use.
I was more wondering where it came from that it damages the transmission to do the service manual method. Most automobile companies have some investment in their transmissions not failing; at least enough invested to not recommend to the dealerships to perform dangerous repair procedures. Despite that, it is consistently reiterated the method people use is to pump a few quarts and refill; I guess I was hoping it had some basis in fact and not just follow the leader. Oh well, I'll let it go.
If someone is going to do the refill method I'd suggest draining the ATF first, adding new ATF, and pumping from there. This allows it to pump new ATF and you are not mixing old ATF with new ATF in the drain sump. I feel this is important because manufacturers that expect you to "replace" the fluid expect it to be a near 100% exchange.
I was more wondering where it came from that it damages the transmission to do the service manual method. Most automobile companies have some investment in their transmissions not failing; at least enough invested to not recommend to the dealerships to perform dangerous repair procedures. Despite that, it is consistently reiterated the method people use is to pump a few quarts and refill; I guess I was hoping it had some basis in fact and not just follow the leader. Oh well, I'll let it go.
If someone is going to do the refill method I'd suggest draining the ATF first, adding new ATF, and pumping from there. This allows it to pump new ATF and you are not mixing old ATF with new ATF in the drain sump. I feel this is important because manufacturers that expect you to "replace" the fluid expect it to be a near 100% exchange.
Originally Posted By: SteveSRT8
Running dry most definitely carries a chance of RUINING the trans pump! Absolutely, positively!
Just like running the engine with no oil in the crankcase, except that transmission fluid is not nearly as good a lubricant, so things get buggered up quicker.
If you watch the exit line and shut the car off the second you see air you are extremely unlikely to damage anything.
My car's service manual says you can run it for up to a minute.
Running dry most definitely carries a chance of RUINING the trans pump! Absolutely, positively!
Just like running the engine with no oil in the crankcase, except that transmission fluid is not nearly as good a lubricant, so things get buggered up quicker.
If you watch the exit line and shut the car off the second you see air you are extremely unlikely to damage anything.
My car's service manual says you can run it for up to a minute.
- Status