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suck up tranny fluid??


jaansu's Avatar
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03-15-05, 12:20 PM   #1  
jaansu
suck up tranny fluid??

My shop recommended their tranny fluid 'vacuum' service in place of the usual drain and replace service for my '90 Camry, claiming this machine removes more fluid than simple draining which gets only ~75% of it. If true, couldn't I just hook up my shop vac to a suction flask, sort of what operating rooms use to catch fluids, connected to a length of plastic tubing, stick this large straw into the fill port and do this myself? What I'm wondering is if the fill port allows access to near the bottom of the fluid reservior as the tubing is not very pliable. I'd be interested in comments whether this would work for this or other cars. I've heard it is done with oil changes.

 
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03-15-05, 12:40 PM   #2  
there is alot of transmission drain and fill machines that hook into the transmission cooler lines to completly change out all the fluid by using the pressure that is normaly produced from the transmission it pumps the fluid out while at the same time fills it with new fluid. this may have been what the shop was refering to if not I would suggest you find a shop that can perform this service.
by just using a vacum I dont see any way to change out all the fluid as you would just be able to suck up the few quarts in the pan and not remove any of the fluid from the torque convertor.

 
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03-15-05, 01:23 PM   #3  
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Bejay: I'm still hoping to avoid the shop charges and find a DIY method. I assume the drain via the bottom port method as recommended in my manual similarly only removes part of the fluid. If so, it seems simplier to try the vacuum method. I'm assuming it's not likely I would damage any internal component trying this? Since it's simple, my theory is to repeat this service, whether draining it or suctioning it, several times between short trips which should replace the majority of the tranny fluid at the end. A lot cheaper throwing away some good fluid than paying the shop. What do you think?

 
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03-15-05, 01:45 PM   #4  
our maxima has a drain plug for the tranny fluid pan. Lots of cars don't have it. I did exactly as you are planning. I would drain what would come out, then refill, drive a couple days, and repeat the same thing. It's a 86 maxima with 261,000 and still has a strong tranny. don't get me wrong. Sometimes I did remove the pan & gasket to change the filter. but mostly it was the add & remove method for me!
-Bob

 
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03-15-05, 03:05 PM   #5  
I experimented with the DIY vacuum method, only to discover that the shop vac is too high volume, low pressure device. Within a few minutes, you will burn up the vac motor, without extracting much fluid, if any. I then stepped the design up and used an old hvac vacuum pump and special resevoiur metal can setup. It works at a very slow pace and I found it to slightly undesirable too, although it did work. However you end up chasing vacuum leaks from pump, thru metal can and lids, etc.

I ultimately installed a drain plug in the transmission pan. Of course, you have to remove the pan to install it, but auto parts stores sell these specialty drain plugs for just that application. I recommend the plug, but be sure it is designed for tranny pans because there is almost no clearance to install a nut on the inside of the pan.

 
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03-15-05, 03:16 PM   #6  
Bob - just curious about your method. How many times did you drain and refill before concluding your process? Assuming you remove about one third with each drain but then when you refill you are adding new oil to old and at some point it makes sense to cease the replacement process. There probably is a mathematical formula which can tell you when to stop. For years the accepted method was to replace only the fluid which drained when the pan was dropped so your DIY replacement method makes sense, but I must admit that I pay for a total replacement every 30,000 miles and view any interim drain and fills as icing on the cake.

 
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03-15-05, 03:57 PM   #7  
It would be a total of 3 drains then alternating to 2 drains the next time then 3 again. I would purchase the fluid by the case when on sale. You are correct about a formula tho! Those total # of drains would be over a period of 85K miles.

 
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03-15-05, 09:18 PM   #8  
As I see it mathematically it would go something like this. If the torque converter holds 1/3 of the fluid which does not get changed out then after the second change the amount of old fluid will be a third of that or 1/9th. After the third change this will be 1/27th. It will never get to zero but will if you kept on doing this an infinite no of times it will tend to zero. The question is at what point should one stop. To me it seems like 3 chnages should be good enough to stop - possibly 4 as this will contain between 3.7% and 1.23% of the orginal fluid (last figure for 4 changes).

 
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03-15-05, 10:53 PM   #9  
tranny

Is it a front wheel drive or a rear?

 
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03-16-05, 09:58 AM   #10  
if you have time...

...or it's worth nothing, then filling and draining repeatedly makes sense altho you'll never get all the old fluid out as previously stated. the fluid exchange procedure is quick and gets virtually all the fluid in one fell swoop. i'd also add that once the fluid is exchanged, the pan should be dropped and the filter replaced. there are advantages to both services (fluid exchange AND filter/gasket replacement) and ideally, both services create the best value for the customer and longevity for the transmission.

 
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