Interesting way of flushing an AT transmission

[mililani]

Hi folks, I'm new here. Long time lurker, first time posting. I have a Honda Civic 2001 LX. It has about 110k miles on it and is due for a transmission fluid change. I've read that Honda recommends three drain and refills. I was browsing around and found this video: http://www.youtube.com/watch?v=MsdPAadc9fY Basically, the guy suggests that you drain the transmission and clean out the metal shavings on the drain bolt. He fills up the transmission with new fluid. Then he finds the transmission coolant supply line and removes that and hooks up another line to a bucket or reservoir. He then starts the car. The idea is to let the engine flush out all of the fluid from the tranny and torque converter into the reservoir thereby clearing out ALL of the tranny fluid. As the engine is dumping out the old fluid, the new fluid is added to maintain, more or less, the level of ATF in the tranny. When the engine starts pumping out clear fluid, the engine is turned off, the fluid levels topped off, and supply line reconnected. So, has anyone tried this before? Thoughts?

[BlueEM2]

This is an awesome way to clog the internal filters on the transmission. Which will restrict oil flow and destroy it over time. On a car with an external filter that's great but our civics have an internal filter which cannot be changed without opening the transmission.

[CrewChief]

Anything at the bottom of your tranny will now be in your filter after the flush so you will have to change the filter. Bad move on our cars. Your best move is to drain, refill and then repeat. Hell if your that worried about stuff at the bottom of your tranny you could always open the bottom drain plug and fill the tranny from the top and let it run out the drain untill it gets mostly clean. Sounds like a big waist of fluid to me.

And if your tranny has thgat much stuff in it you have bigger problems then just needing a fluid change.

[pjb3]

I don't think there would be a problem with clogging the filter. All you are really doing is adding clean ATF. If adding fluid is causing particles to be loosened and circulated then that will happen no matter if the old fluid is drained from the pan or the cooler line.
A couple of things in the video make me uneasy. First, I don't like using Dexron fluid in a Honda. I know he is doing it because the manual says you can use it in an emergency and because it is cheaper and he plans to do a second flush with Honda ATF. No flush ever removes 100% of the fluid so some Dexron will remain. I would just do a single flush with Honda ATF. I have heard other people suggest a slightly different method in which the line going to the cooler is placed in a bucket like the video but a second line is attached to the return line from the cooler and placed in a large, clean container with fresh ATF. The difference is the transmission is sucking clean fluid at it's own rate instead of pouring it down the filler tube and hoping you keep up or don't overfill. You simply stop before all the fluid is gone from the clean fluid container.
My Civic is a MT, but I also have an Integra and Camry that are automatics. In both the ATF got a little darker than I liked before I realized it. In both I did 3 drain and fills each about a week apart to get the fluid clean again and now I do a drain and fill every 10k miles and the fluid looks perfect.

[BlueEM2]

^ I'm not reading your whole post because it's long. I assure you, it plugs up the internal filter. You drain the bottom of the tranny which is full of shavings and debris and jam it into the filter which would in no way happen anyway. It's your choice, but it will destroy the transmission. The only time you ever flush these transmissions is if they are coming out of the car for repair. That's Honda's own recommendation.

[mililani]

Originally Posted by pjb3

I don't think there would be a problem with clogging the filter. All you are really doing is adding clean ATF. If adding fluid is causing particles to be loosened and circulated then that will happen no matter if the old fluid is drained from the pan or the cooler line.
A couple of things in the video make me uneasy. First, I don't like using Dexron fluid in a Honda. I know he is doing it because the manual says you can use it in an emergency and because it is cheaper and he plans to do a second flush with Honda ATF. No flush ever removes 100% of the fluid so some Dexron will remain. I would just do a single flush with Honda ATF. I have heard other people suggest a slightly different method in which the line going to the cooler is placed in a bucket like the video but a second line is attached to the return line from the cooler and placed in a large, clean container with fresh ATF. The difference is the transmission is sucking clean fluid at it's own rate instead of pouring it down the filler tube and hoping you keep up or don't overfill. You simply stop before all the fluid is gone from the clean fluid container.
My Civic is a MT, but I also have an Integra and Camry that are automatics. In both the ATF got a little darker than I liked before I realized it. In both I did 3 drain and fills each about a week apart to get the fluid clean again and now I do a drain and fill every 10k miles and the fluid looks perfect.

Yeah, that's pretty creative putting the new fluid into the receiving line to maintain equilibrium of the fluid. And I agree. I don't see how debris and shavings on the bottom of the tranny will be perturbed by this method. Wouldn't the tranny do that when the clutch is engaged? I digrees. I'm no transmission expert. Oh well, tbohar seems to disagree with this method. Honda also recommends the drain and refill method.

[mililani]

Originally Posted by tbohar

^ I'm not reading your whole post because it's long. I assure you, it plugs up the internal filter. You drain the bottom of the tranny which is full of shavings and debris and jam it into the filter which would in no way happen anyway. It's your choice, but it will destroy the transmission. The only time you ever flush these transmissions is if they are coming out of the car for repair. That's Honda's own recommendation.

Tbohar, I mean this as no offense, but how do you know this for a fact? Are you a Honda certified mechanic? Just curious.

[CrewChief]

I say its your car and you do it your way. You are obviouly convinced that it will work.

But I ask you please report back to us when your tranny filter being clogged blows your tranny. the fliter is before the coller lines and the fills back through the tranny. Think of it like an oil pickup and oil fliter or a return fuel system. Same concept. The more nasty shit you unearth from the tranny the more your filter picks up.

But I stand by saying that if you drain your tranny fluid and there is metal shavings in your tranny you have bigger problems than dirty fluid.

[BlueEM2]

Honda knows these cars better than me, and you. They say to drain and fill for a reason. So, drain and fill unless you want transmission issues. The reason they recommend this is so the oil at the bottom which has the shavings does not pass through the filter. I'm going to leave this at that because you will do what you want anyway, and I'm not going to argue it. I'm going to use my better judgment and listen to the engineers with many years of education who get paid way more than I do and designed the system.

[BlueEM2]

Well, I just put some thought into this and this method would be pretty similar to a drain and fill. You would not drain all the old fluid out though. I don't understand why you would ever do this when the drain and fill is so easy. Not only is it less risky because you don't have to start the car but you also don't have to remove any cooling lines. I guess if your not draining all the oil out and your pulling oil out of the return line on the tranny you shouldn't pull shavings, hopefully. I'd stick to drain and fill though.

[gearbox]

filter clogging aside, adding a whole 9 qts of new fluid to an old trans with deposits is gonna cause alot more problems than only changing 3 qts with new fluid and still having alot of old mixed in. less chance for a big fail. i hear it all the time. trans is fine, they do a flush, then its slipping afterwards. and there is no going back, youre screwed until a rebuild.

[mililani]

Well, I guess I'm going to stick with the drain and fill method. Sticking with the Honda recommended way.

[BlueEM2]

Glad gearbox chimed in here, he is the guy that knows

[pjb3]

I'm not a big fan of transmission flushes. In many cases I think that shops push then as a profit center. They bought the machine and it needs to make money. To make matters worse some push a "flush" instead of just a fluid change. For a flush they run a fluid that is supposed to clean deposits and condition seals and then they replace the ATF. I agree that if a transmission has been neglected then a flush that removes deposits is NOT a good idea, especially if you can not replace the filter. At the same time I don't think that just replacing the ATF should cause a problem.

The one time I would recommend a fluid exchange with a flush machine is if the fluid is badly contaminated or burned. Most flush machine leave 10 to 15% of the old fluid behind while changing 3 qts of ATF 3 times in a transmission that hold 9 qts leaves 29% of the old fluid behind.

[TXFred]

I ran across this thread while researching the transmission oil change on my 04 DX.

I have a question. Why is a large amount of new transmission fluid a bad thing? Is the old fluid beneficial in some way?

[02civicsi02]

This method will clog the filter and cause alot more damage than you think just trust us ok. And like gearbox said flushing an old tranni is a very bad idea especially with that much fluid. Even honda recommends not to flush a high mile tranni cause it will cause the tranni to mess up and slip. You are only suppose to flush the tranni with low miles. Just drain and fill like you are suppose to.

[BlueEM2]

^ I wish I could agree with you but you aren't supposed to flush even a low mileage transmission. During the manufacturing process and first few thousand miles a lot of shavings build up in the transmission casing that will clog the filter just as quickly as with an older transmission. So, you aren't supposed to flush ANY transmission Not in our civics anyway.

[02civicsi02]

Originally Posted by tbohar

^ I wish I could agree with you but you aren't supposed to flush even a low mileage transmission. During the manufacturing process and first few thousand miles a lot of shavings build up in the transmission casing that will clog the filter just as quickly as with an older transmission. So, you aren't supposed to flush ANY transmission Not in our civics anyway.

True but Honda does say to flush it only with low miles. I have never flushed any of my transmissions and never will unless I have to crack it open and rebuild it or something like that.

[mililani]

Originally Posted by TXFred

I ran across this thread while researching the transmission oil change on my 04 DX.

I have a question. Why is a large amount of new transmission fluid a bad thing? Is the old fluid beneficial in some way?

Uhhhh, new transmission fluid is never a bad thing. Old fluid is definitely not beneficial. If there was a way to get all of the old fluid out without clogging the AT filter and replacing it with new fluid, that would be the best route. However, since the Civic AT is designed with a built in filter, nearly unreplaceable filter, you can't do it. After reading johndeerebones' thread on his tranny problem, I can now understand why people on here are against the aforementioned method on flushing the tranny fluid.

[Nosepicker]

Originally Posted by mililani

After reading johndeerebones' thread on his tranny problem, I can now understand why people on here are against the aforementioned method on flushing the tranny fluid.

Link please.

[02civicsi02]

Originally Posted by mililani

After reading johndeerebones' thread on his tranny problem, I can now understand why people on here are against the aforementioned method on flushing the tranny fluid.

We are all against it because honda says not to flush the tranni easy as that.