any potential harm if underfilled ATF?

[danz75]

Subject: 03 Outback legacy wagon A/T fluid low

I recently checked my ATF and realized that I needed quite a bit more. about a quart and a half. There are no leaks in the garage and the last time I crawled underneath(June 07), I did not see any obvious signs of leaks. I have to admit that I have not kept up with checking the fluids as often as I should be.

ATF was replaced with mobil syn dexron III ATF about 2 years ago. No obvious signs of distress with the tranny except that when switching from N to D or R, there is a few second delay for it to engage. I figured it's was normal.

 

I topped it with more fluid until it was above the hot low level and i'm not sure if it's a mental thing but accelerating and climbing hills feels more confident, the gears would not switch to higher or lower until there was enough speed. changing gears also felt smoother.

 

My concern is I'm not sure when the fluid got so low and would it have done any damage to the tranny? the other question is how I would lose so much ATF without any leaks on the garage floor?

 

BTW, in case anyone asks, I did drive around for awhile till it reached operating temp and then parked it on a level surface. Went through all the gears, moving the car a few feet each gear and then left it in P with the engine idling. Waited for a couple minutes for the fluid to settle before putting the dipstick in to check level.

[Setright]

Is it possible that the 'box was underfilled at the change 2 years ago?

 

If your car still performs well, now with the correct the amount of oil, you've probably not damaged it very much.

[danz75]

Is it possible that the 'box was underfilled at the change 2 years ago?

 

If your car still performs well, now with the correct the amount of oil, you've probably not damaged it very much.

 

Since I did the conversion to synthetic ATF, I did the drain and fill process 4 times to get as much fluid replaced as possible and I remember clearly that each time, I checked the fluid level at operating temp. It might be possible that I underfilled it but I doubt it since I did it 4 times and had to check it each time. I'll go under the car again this weekend and see if I can find any leaks.

[crazyhorse001]

The primary causes of tranny leaks are lines, fittings & seals. My money is on a pinhole in a line.

[davebugs]

I bought a 97 0r 98 Legacy outback one time with a tranny leak.

 

Ended up being the external filter had a pinhole in it.

 

38 bucks it seems to me for a dealer filter. I just priced a Wix ATF filter for my girlfriends 2006 Impreza. Dealer is like 39, Wix is like 8 bucks.

 

Check that filter - not just the seating area - my leak was coming from the opposite end.

 

Dave

[OB99W]

[...]the other question is how I would lose so much ATF without any leaks on the garage floor?[...]

Assuming the loss was actually due to a leak (three pints is a lot to lose without any obvious external sign), consider that the leak may occur only under pressure, and with the engine turned off in your garage it might not happen. Or, it may be that a shaft seal only leaks when under certain operating condition stresses.

 

Have you checked your other fluid levels; front diff, for example?

 

The radiator has a transmission cooler mounted inside it, and a small hole in that could cause some ATF to mix with the coolant. However, three pints would normally cause a noticeable increase in the coolant reservoir level (as well as obvious "gunk"), so that's not very likely, and in addition some coolant usually winds up in the ATF.

 

Do you always do your own engine oil changes, or occasionally go to one of the "quick-change" places? Sometimes the guys at those places yank the wrong drain plug. If they realize it, they might put the plug back rapidly and ignore the loss of ATF, or underfill it even if trying to correct the mistake.

[OB99W]

I bought a 97 0r 98 Legacy outback one time with a tranny leak.

 

Ended up being the external filter had a pinhole in it.[...]

I've had them rot through from road salt. It starts out with very slow seepage. However, the garage floor did not remain dry.

[johnceggleston]

in other threads , for earlier years, there has been a good bit of discussion about the difficulty in reading the AT dip stick. i would check it cold over time, not for proper level so much as to see if it changes. if the cold level drops over time, you have a leak.

[danz75]

Have you checked your other fluid levels; front diff, for example?

When I changed the ATF, I also changed the front and rear diff. I just checked them last week and they're at the right levels.

 

The radiator has a transmission cooler mounted inside it, and a small hole in that could cause some ATF to mix with the coolant. However, three pints would normally cause a noticeable increase in the coolant reservoir level (as well as obvious "gunk"), so that's not very likely, and in addition some coolant usually winds up in the ATF.

I did look into the overflow bottle but did not notice any obvious gunk.

 

Do you always do your own engine oil changes, or occasionally go to one of the "quick-change" places? Sometimes the guys at those places yank the wrong drain plug. If they realize it, they might put the plug back rapidly and ignore the loss of ATF, or underfill it even if trying to correct the mistake.

 

Yes. I've not taken it to any quick lube shops. Apart from the coolant(which I had smart service in seattle do), I've done all fluid replacements myself.

[danz75]

in other threads , for earlier years, there has been a good bit of discussion about the difficulty in reading the AT dip stick. i would check it cold over time, not for proper level so much as to see if it changes. if the cold level drops over time, you have a leak.

 

I do agree that it is a little more confusing. I'll take your suggestion of checking it cold and monitor it over a few months to see if there's any obvious level changes.

[danz75]

I bought a 97 0r 98 Legacy outback one time with a tranny leak.

 

Ended up being the external filter had a pinhole in it.

 

38 bucks it seems to me for a dealer filter. I just priced a Wix ATF filter for my girlfriends 2006 Impreza. Dealer is like 39, Wix is like 8 bucks.

 

Check that filter - not just the seating area - my leak was coming from the opposite end.

 

Dave

 

it was replaced with the subaru atf filter. I'll look at it this weekend to see if there's any leaks around there. ATF should be quite noticeable because the fluid is red and not like motor oil or gear oil. When I pulled the diptstick, the ATF was still nice and red so any drips should be obvious.