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Old 10-01-2018, 02:27 PM
ruffyz ruffyz is offline
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Default Why does my transmission fluid look clean, but is dirty

I just drained my transmission fluid on my beater and the fluid was nasty, but the fluid on the dipstick currently does and has always shown nice and clean.

My first guess would have been a busted pump, but when I disconnected one of the cooler lines fluid does pump out. What gives? How is it possible for the diptstick to have clean fluid on it but the rest of the system have some really dirty stuff?

The car is a 1998 Volvo S90 with an Aisin AW30-40LE (seen in some Toyota trucks and a few Lexuses). I'm draining, replacing filter, and flushing the fluid because it started to throw selector switch and lock up solenoid codes.
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Old 10-01-2018, 03:11 PM
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Heard from my son when he was a Tech, if the fluid is clean when pumping it out to flush, don't bother replacing the filter. If filter has crap in it transmission is probably toast.
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Old 10-01-2018, 07:58 PM
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Originally Posted by ruffyz View Post
I just drained my transmission fluid on my beater and the fluid was nasty, but the fluid on the dipstick currently does and has always shown nice and clean.

My first guess would have been a busted pump, but when I disconnected one of the cooler lines fluid does pump out. What gives? How is it possible for the diptstick to have clean fluid on it but the rest of the system have some really dirty stuff?

The car is a 1998 Volvo S90 with an Aisin AW30-40LE (seen in some Toyota trucks and a few Lexuses). I'm draining, replacing filter, and flushing the fluid because it started to throw selector switch and lock up solenoid codes.
Sample size and presentation format. Looking through 1/32 of an inch of fluid on a metal stick is not same as looking at a drain pan full.
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Old 10-02-2018, 09:29 AM
ruffyz ruffyz is offline
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Quote:
Originally Posted by Vicegrip View Post
Sample size and presentation format. Looking through 1/32 of an inch of fluid on a metal stick is not same as looking at a drain pan full.
The dispariy is too great for me to think this is the case, but that would have been great.
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Old 10-02-2018, 10:41 AM
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The dispariy is too great for me to think this is the case, but that would have been great.
Am not there so donít know the conditions observed You could stick the dipstick into the used fluid you drained and see if it looks the same as when you sampled from the trans.
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Old 10-02-2018, 10:56 AM
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I would be concerned as to why the tranny fluid is that dirty.
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Old 10-02-2018, 11:10 AM
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I just flushed the trans on my track only 944. I was surprised that it still came out blue like the Swepco that went in. It still had some grunge in it like Vice says. Even engine oil is cleaner on the stick than the pan.
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Old 10-02-2018, 12:12 PM
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I thought it was just the sample size and light, just like looking at a cup of coffee. Plus, you are getting all the debris from the sump/pan from the drainplug and not the dipstick. But, I like to boil things down, limited brain power I guess.
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