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Last Post 19 Dec 2008 06:36 PM by  atcovan
External filtration for automatics
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atcovan
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10 Dec 2008 04:18 PM
    I see there is a filter specific for trans fluid, such as the WIX 57702 cartridge for the Super Duty Fords, rated for 1 micron. Can I use a standard engine oil type, which are usually rated at 19 microns, or is that useless because of the larger micron rating? I have an Aveo which has no filter at all, so I'd like to try something external. Your thoughts, please.
    Steve Hoelscher
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    10 Dec 2008 05:03 PM

    atcovan wrote:
    I have an Aveo which has no filter at all, so I'd like to try something external. Your thoughts, please.

    You're towing with an Aveo? [;)]

    I can assume your Aveo is an automatic? It does have a filter. However, most automatic's filters look like a piece from a pair of nylon stockings stretched over the opening in the fluid pickup. There are a few with true external, spin on type filters. The early Saturns had them.

    The OE filter is going to work fine so there is no need for additional filtration. The reason is that the ATF in your automatic doesn't get contaminated like the motor oil does in your engine. There is no combustion process, nor induction system, to contaminate the fluid. The only thing that is there to contaminate the fluid is clutch material or debris off the internal metal components.

    True, you don't want the clutch material or the metal debris circulating through your transmission but if there is enough of that stuff suspended in the oil to cause a problem, you already have a problem. That clutch material or metal debris is the symptom of a bigger problem, its not the cause of a problem.

    Also, modifying the transmission to put an external filter on it isn't easy. About the only option is to do an inline filter in the cooler lines. However, that is a flow restriction and you really don't want. Also, if the fliter plugs up or developes a leak, you could cause a much bigger problem than you prevent.

    atcovan
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    10 Dec 2008 05:30 PM

    Thanks for the reply, Steve. While I won't be towing with my little Aveo, I figured auto-x may be as stressful, and yes, it's an automatic. I will keep to a regular replacement schedule (say, 15k?) and use a quality fluid. I haven't dropped the pan to see, but the dealer and Kragen each said there's no filter in there. I'll find out soon.

    PS If the drain oil looks like brown motor oil, can I assume something bad is going on, or about to happen? I don't know the service history on this unit, but at 45k miles, it still runs well, with no noticeable slipping at WOT shifting.

    Steve Hoelscher
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    10 Dec 2008 08:04 PM
    atcovan wrote:

    Thanks for the reply, Steve. While I won't be towing with my little Aveo, I figured auto-x may be as stressful, and yes, it's an automatic. I will keep to a regular replacement schedule (say, 15k?) and use a quality fluid. I haven't dropped the pan to see, but the dealer and Kragen each said there's no filter in there. I'll find out soon.

    Its possible it doesn't have a filter. No telling with Daewoo. The Aveo came out about the time I left the biz so I never saw one in my shop. For the most part, the "filter" in an automatic is only there to keep the pump from ingesting large chunks of stray transmission parts. So eliminating the filter isn't a big deal.

    atcovan wrote:

    PS If the drain oil looks like brown motor oil, can I assume something bad is going on, or about to happen? I don't know the service history on this unit, but at 45k miles, it still runs well, with no noticeable slipping at WOT shifting.

    At 45K miles, its due for a fluid change. Check with the dealer as to what type of fluid it takes. If its a specialty fluid, let me know. Otherwise, if it uses a Dextron fluid (and it likely does) then buy a quality, name brand fluid. Castrol, Havoline, etc.... And then change it annually from now on.

    When you drain the fluid, it should have a pale red appearance and have a sweet smell. A light brown tint is normal for old, high mileage fluid. A darker brown color is varnished. Very dark brown or black is burnt. A pale yellowish brown (like cooking oil) colorand a sickening smell is badly overheated fluid. If it has a sheen too it that's metal contamination (aluminum).

    I would expect it to be pretty close to normal with that mileage. But that doesn't mean it doesn't need changing. I change the fluid in all of my automatics annually. It always looks like new when I drain it. If its looking nasty, its already too late.

    atcovan
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    11 Dec 2008 12:44 PM
    Hi Steve, After a bit of research, this is an AW81-40LE manufactured by Aisin in Japan. There's just a screen pickup and it calls for Dexron III fluid. The initial drain was kinda dark red, almost brown, but no sign of sheen or rainbow metal and no awful smell. The next drain came out almost the same, just a bit more red. Each time takes 3 quarts, so I'm going to flush it out a couple more times, until it's clean. There was no debris in the pan, so I hope I have many more miles to go. I'm planning to install a big cooler after the radiator, as a precaution. Thanks for all your help.
    Steve Hoelscher
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    11 Dec 2008 01:58 PM

    atcovan wrote:
    Hi Steve, After a bit of research, this is an AW81-40LE manufactured by Aisin in Japan. There's just a screen pickup and it calls for Dexron III fluid. The initial drain was kinda dark red, almost brown, but no sign of sheen or rainbow metal and no awful smell. The next drain came out almost the same, just a bit more red. Each time takes 3 quarts, so I'm going to flush it out a couple more times, until it's clean. There was no debris in the pan, so I hope I have many more miles to go. I'm planning to install a big cooler after the radiator, as a precaution. Thanks for all your help.

    OK, that's an Aisin/Warner. I know Aisin/Warner but that must be a new unit. Not suprized. Aisin makes a pretty good unit as a general rule. It should be fine.

    When you drain the fluid remember that nearly half its total volume is trapped in the torque converter and cannot be drained. So changing it multiple times is a good idea. Each time the fluid will get better as it dilutes the fluid that can't be drained from the torque converter.

    For this reason, its always a good idea to change fluid BEFORE it gets ugly. Most people assume that because it looks good, it doesn't need changing. Then when it gets to looking nasty, because you can't change the entire volume of fluid, it takes a thorough flush (and that doesn't get it all) or multiple changes to do the job. So if you change it regularly, on a frequent schedule, before it gets dirty, it never gets that way and you are always in good shape.

    Primetime Glick
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    18 Dec 2008 09:25 AM
    Steve Hoelscher wrote:

    Also, modifying the transmission to put an external filter on it isn't easy. About the only option is to do an inline filter in the cooler lines. However, that is a flow restriction and you really don't want. Also, if the fliter plugs up or developes a leak, you could cause a much bigger problem than you prevent.

    http://perma-cool.com/Catalog/Cat_page25.html

    This diagram sure as hell makes it SEEM easy, except for tapping the pan to accept the supply/return line fittings. An email is in to Perma Cool to supply me with an instruction manual... I also don't know how the whole system is pressurized.

    This is what I want to install in my next tow vehicle (in conjuction with a cooler), because it seems like it makes it easier to change fluid and clean the filter, and it packages in the temp gauge and fitting.

    Steve Hoelscher
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    18 Dec 2008 05:06 PM

    Primetime Glick wrote:

    This diagram sure as hell makes it SEEM easy, except for tapping the pan to accept the supply/return line fittings. An email is in to Perma Cool to supply me with an instruction manual... I also don't know how the whole system is pressurized.

    It is easy, on your truck. Its a lot more difficult in the confines of the front end of an Aveo. Not to mention, that kit is designed for a truck, not a tiny little Aveo. And you don't need to tap the pan for a return line. There already is a return line in the case. You simply cut the cooler line and plumb in the filter.

    Primetime Glick wrote:

    This is what I want to install in my next tow vehicle (in conjuction with a cooler), because it seems like it makes it easier to change fluid and clean the filter, and it packages in the temp gauge and fitting.

    I wouldn't. These spin on external filters are more of a problem than a help. The transmission isn't designed to pump through that dense a filter. You will end up with a pressure loss and a flow restriction. And as I previously stated, if there is enough material in the filter to need filtering out, you already have a problem. Ultimately, the filter will stop up and fry your transmission. Dodge trucks are famous for this.

    If you want to make it easy to change the fluid, install a valve in the pan. And changing that external filter doesn't do a thing for the internal filter. You still have to drop the pan to change that one.

    There simply isn't a need for an additional filter.

    atcovan
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    19 Dec 2008 01:28 PM
    So, if I have understood correctly, if we change the fluid and factory filter regularly with a quality fluid and not wait for it to get ugly, plumb a big-ass cooler on the return line (after the radiator has done it's best) and mount it front/center for maximum cooling airflow, and don't exceed the manufacturer's weight recommendations, we should get reasonable service from our automatic transmissions without spending hundreds for gadgets that may do more harm than good. Hmm, makes sense to me! All great advice, Steve.
    Steve Hoelscher
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    19 Dec 2008 03:28 PM

    atcovan wrote:
    So, if I have understood correctly, if we change the fluid and factory filter regularly with a quality fluid and not wait for it to get ugly, plumb a big-ass cooler on the return line (after the radiator has done it's best) and mount it front/center for maximum cooling airflow, and don't exceed the manufacturer's weight recommendations, we should get reasonable service from our automatic transmissions without spending hundreds for gadgets that may do more harm than good. Hmm, makes sense to me! All great advice, Steve.

    Yep. Pretty much. [:)]

    You really don't need a big-ass cooler. One of these would work just fine:

    http://www.oregonperformancetransmission.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=OPTI&Category_Code=HAY

    That's what I use on my daily drivers. And I bypass the radiator. The van that I tow with has a standard external cooler. No issues.

    atcovan
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    19 Dec 2008 06:36 PM
    The link didn't work, but I did go see their site. I have the big Hayden on my 8-passenger Chevrolet van I use as an airport shuttle. I can see the potential issues with water getting into the trans with a rotted-out heat exchanger, but wouldn't this help warm things up in the very cold climate? Or, do you see this as another unnecessary load on the engine cooling system? I'm in the central CA valley, so it rarely gets under 30 degrees.
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