Mechanics

AUTO TRANSMISSION ********"

1998 Mercury Mystique • 4 cylinder 2WD Automatic • 153 miles

The transmission has had no issues in the past, but did have the trans fluid changed around 2 years ago as regular maintenance. A few days ago it started slipping on the freeway, around 65-70mph. The engine would rev to about 3,000rpm very suddenly, then the trans would *****" back into gear very roughly and the rpm's would go back down to around 2500 or so. Even going at a steady 65, without braking or letting off on the gas, it would still randomly slip***** like this, maybe every couple minutes, give or take.

This does not seem to happen in the first 2 (maybe 3) gears. It seems to be mostly in 4th gear and the lowest mph that I have noticed it at is around 40mph.

Checked the fluid and the level is normal, color is deep redish-brown. Looks normal and no metallic specs can be seen.

I'm just wondering if anything could be causing this OTHER than the gears themselves. Perhaps electronic, or sensor related, etc.

One other thing that I noticed under the hood is that there is a vacuum hose that is coming out of the top of a case that appears to be attached to the side of the transmission. The tube is coming right out of the top of the case and goes over to the battery area, but just stops there, and it is not connected to anything (perhaps a breather?). It is very deteriorated and cracking, especially at the base where the hose clip attaches it to the case. Don't know if this is even critical, since the tube goes nowhere, but I thought I should mention it.

Anyway, I just want to make sure any reasonably simple options/possibilities are ruled out before I take it in.

Thanks so much for your advice!
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Ben Lee
January 13, 2011.




I just went through this with another Ford in another thread. It eventually turned out to need to be rebuilt. The hose is a breather, Ford transmissions are electronically actuated these days, they dont use vacuum modulators. The condition of the fluid could indicate internal band/clutch degradation.

Dr. Hagerty
Jan 13, 2011.
Does my description of the fluid not sound like what the "normal" appearance should be? I thought deep redish-brown was normal. It's definitely not black and is still transparent, and there are no metallic flakes or anything like that.

Oh, and there are no stored codes and no pending codes.

I also noticed in some other question threads that very similar instances could be caused by various sensors, such as the speed sensor, the throttle position sensor, the mass airflow, etc.

My scan tool allows me to view live data, but I don't know what values to look for. I can also use my DVOM to test applicable sensors, but again, I don't know what values to expect.

Thanks!
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Tiny
Ben Lee
Jan 14, 2011.
By all means, follow the path that the other threads have laid out. If there is something that can be done such as replacement of the fluid or the replacement of a sensor, then there is where I would follow. The single biggest disadvantage to cyberspace (in my opinion) is that I can't lay my hands on the car.

Dr. Hagerty
Jan 14, 2011.

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