Toyota Repair: Transmission Noise, metal particles, picket fence

Question
Hi Ted,

I have a 1995 Camry LE with 4 cyl engine and 158K miles. The first letter of the VIN is a J.

The automatic transmission has been making a noise in first and second gear that is hard to describe. I hear this noise while driving in the passenger compartment. The noise can be described as between the sound of running a stick across a picket fence and a rattling sound.

When I have the car up in the air on a rack and I am sitting under the motor, I hear a distinct rattling sound which I am not sure is coming from the engine's oil pan or transmission.

When the transmission gets very warm after say 5 to 10 miles of driving, the noise decreases to the point I don't really detect the noise from inside the passenger compartment after the transmission is warmed up.

I started noticing this sound in June after cleaning the EGR valve at 156K miles. To clean the valve I removed the big EGR metal tube from the motor's block pulling both the tube and EGR valve as a unit from the car. Then I removed the EGR valve from the metal tube. Cleaned the valve, connected the tub with the big nut back to the EGR and attached the  big pipe to the motor's block again.

At first I thought maybe the sound was coming from this metal EGR tube or connection, but when the sounds changed shifting from 1st to 2nd then disappears in 3rd, I assumed it must be the transmission.

Transmission fluid was changed by my local Toyota garage in July of 2007.

What could be causing these sounds, Ted?

Many Thanks!

Mike

Answer
The problem is most likely in the differential, when the transmission fluid is changed the differential oil is not,there is no passage for the transmission fluid to go through, I would recommend draining the differential oil for inspection, look for metal particles on the drain plug magnet.