AT Trans Fluid Overflow

[DavidPeab]

After I drive my 2000 H4 2.5L OBW long enough for it to warm up, when I check the trans fluid the dip stick "pops" when I take it out without the engine running, the ATF flows out of the dip stick tube. It literally burbles out like the fluid is way overfilled. It seems a bit clunky when shifting up or down. Sometimes at stop lights I smell something hot or burning. I assume it is the ATF flowing out and hitting the manifold. Otherwise it runs fine and shifts well enough to get around. Also, the fluid level looks fine (a 1/4" high due to my earlier work - below) when the engine is running.

I noticed it was high the last time I checked it, so I took a siphon and sucked out a couple of quarts. After checking it with engine running it seemed a bit low, so I added a quart and it seemed spot on. The fluid I took out looked pretty brown so I order an OEM Subaru filter and was planning on changing it, using the method I read about here: Changing Automatic Transmission Fluid (is easy)

I don't think this is normal and hope someone here can give me a clue as to what the problem might be.

[cardoc]

There are vent tubes running from the top of the transmission that may be clogged. The pressure is building within the case and when you pull the stick, the pressure is released.

When pressure builds up, flow suffers, so it is possible that the clutches may have begun to slip, you just haven't noticed it much because of the adaptive shift programming in the TCM.

Flush the system good. Pull off the vent tubes and clean them out. If the tubes end up being free from debri, you have an issue with venting inside the case.

[subiesailor]

If the vent tube cleaning doesn't change the over flow issue. Another possibility good friend had this very same issue with a Ford for years and years took it to several different dealers and got the same old story. 5yrs of this finally some old grizzled mechanic at the local dealer listened to his description of what was happening took a 30 second look at the truck and told the lacky shop crew to check the cooling lines and cooler for any blockages. Bingo blockage in the cooler caused by a rock strike that pinched the feed line. New cooler and the old truck was perfectly fine he had it till just 2yrs ago 200,000 miles the last 100K was trouble free of the AT fluid over flow issue.

Good luck

For sure flush it good and clean up the vents see how that goes.

[DavidPeab]

OK, can you guys describe where the vent tubes are? Will I be able to see or find them when I am under there to change the ATF and filter? Any suggestions on how to clean them - coat hanger, compressed air, etc.?

I had a radiator flush and fill when I had the timing belt, water pump, idlers, etc, done. Could something during that process have caused these symptoms?

[ntippet]

They are located on the top of the trans under the firewall/bulkhead.
Behind where the air intake bracket support bolts to the transmission.
In this photo the black line on the RH (passenger) side is the transmission vent.
The line on the LH (drivers) side is the front differential vent.

[ntippet]

There is also another slightly different vent tube design, but the vent location is the same.
The small upside down U shaped tube is the trans vent.

[DavidPeab]

So they are the two hoses in your pic running from the top of the trans over the electrical connectors just where the trans mates with the diff, forward of the filter but NOT the metal and rubber tubes right beside the filter?

Bear with me. I've never done any tranny work. Are they accessible? If so, how would you recommend unclogging them?

Could this also be related to blocked cooling lines (mentioned by Subiesailor above) that may have occurred during my recent timing belt/water pump replacement and cooling system flush and fill?

[DavidPeab]

The small upside down U shaped tube is the trans vent.

It's much easier to see in that pic. Same questions as above though.

[ntippet]

Yes the 2 lines on the top of the trans.

Depending on the size of your hand and how flexible you are they can be accessed from the top.
They are in a tough spot to reach, from the bottom may not be easier since the exhaust is usually blocking any ability to reach up that high.
To (check) unclog them simply disconnect from the vehicle, remove and blow out with compressed air.

[DavidPeab]

I'll give it a shot and let you know how it goes.