Unexpected RPM increase after changing Trans fluid

[aircraft engineer]

OK - drew out 5 qts and replaced it. RPM seems to be up a thou or so (I haven't driven it, this is hearsay)

 

It supposedly did the same right after she bought it but then it settled down a couple hundred miles later.

 

I pulled out the dipstick and it was "brown" (it WAS red when I looked at it right after she bought the car), so did a 5 qt swap and I suspect that it had been done the same right before we looked at it (since I ALWAYS look at ATF on a "new purchase")

 

She says she will do a total flush when she gets to PHX next week

 

Ideas?? (didn't smell "burnt" though, just brown color)

[four-fleet-feet]

Ok, as he forgot to mention, it's Dragon again. See to right for what she is. Auto trans.

 

RPMs are up to over 3000 while climbing at freeway speed, and won't come down unless I manually punch and release the gas pedal to make her shift. I've never had a car with a tach before, and she did this the first two weeks I had her, then stopped. I thought it was due to the snow we were having at that time.

 

Before the fluid exchange she was climbing at 60 about 2500 max, maybe a spike just over the line of 2500. Now it's up to 3250 and stays there unless I level out or make her shift.

 

The only other thing I've been doing is using the engine to brake going into/out of aircraft-engineer's house (farm area, hilly and winding roads). I've been putting her into 3rd and not going over 38 down the hills. Could this have caused the abrupt fluid color change? Dragon's a lead sled compared to my old truck (over 1,000 lbs more weight than an S-10). I'm going to really fly down the Siskiyous if I have to rely on brakes alone. I know better than to overheat them on that descent.

 

If we'd known about this a month ago, I'd have taken her into a dealer for a flush then. Too late now. I'm leaving St. Pat's day OR ELSE. Anyone have any thoughts about what to do/not to do between Grants Pass and Redding so I don't have a broken-winged Dragon upon arrival in Hades? (Uh, I hate Phoenix, can't you tell? Only for you, Mom...)

[OB99W]

[...]Ideas?? (didn't smell "burnt" though, just brown color)

Assuming a cause/effect relationship, perhaps the fresh fluid broke free some "crud" that's now sitting somewhere detrimental. Or maybe the trans isn't happy with characteristics of the new fluid (true Dexron-II or -III are no longer available). What fluid was used?

 

OTOH, the problem arising and change of fluid might just be coincidence; possibly something else got disturbed while the work was being done. TPS, VSS, etc., difficulties could cause the symptom described.

 

A recent somewhat-related thread:

http://www.ultimatesubaru.org/forum/showthread.php?t=85096

[four-fleet-feet]

Valvoline Dexron-Mercon. The red bottle. Says it's good on all Subarus. Found out later National actually did stock Dexron III (at less than 1/2 the price). I just had to get the new guy. He didn't know they carried it in the back.

 

I'd like to do the flush before I leave, but there's no time. I think I'll have a PHX dealer do the flush even if the problem stops - the problem might be the fluid the previous owner used and the Valvoline just don't mix with whatever was in there before December of last year. Who knows what was in my poor car before that?

 

Previous owner seems to be the 'buy it, drive it, kill it, buy another used car, repeat' type. Although she said otherwise, I don't think she did any regular maintenance. Thank goodness it's hard to kill an Imp.

 

Not that I can call and ask - no answer on phone # of previous owner.

[86BRATMAN]

Not sure on your terrain, but here in the mountains its not uncommon for my mom's 98 Legacy to run a touch over three on a hill to keep highway speed. From what I can tell from here, it almost sounds like the torque converter isn't locking/unlocking like it should. And causing it to hang in gear.

[OB99W]

Valvoline Dexron-Mercon. The red bottle. Says it's good on all Subarus. Found out later National actually did stock Dexron III (at less than 1/2 the price). I just had to get the new guy. He didn't know they carried it in the back. [...]

The Dexron-III is likely old stock, since GM stopped licensing it a while back; it also might list Mercon on the label, since the frictional and other characteristics allowed for that. What you got is probably "compatible", but as you mentioned who knows what was in there before.

 

I didn't mention this previously, because I don't see a connection to an ATF change, but seemingly unrelated things can cause strange shifting in electronically-controlled transmissions. Somewhat-dragging brakes can confuse the ECU/TCU, since throttle angle that's detected would be higher than expected for the road speed; the electronics "thinks" you're on a steeper hill than you actually are and upshifting can be suppressed. If you have any reason to suspect the brakes aren't releasing fully, it might be worth looking into that.

[aircraft engineer]

nope - gathers speed downhill just a soap box derby racer. No indication of dragging brakes

[86BRATMAN]

Even a seamingly non noticable brake drag can effect fuel mileage. I have no reason to doubt that it *could* be causing this problem as well.