DRIVERS ASK, TOM ANSWERS:

TRANSMISSION PROBLEMS SOLVED

Dear    Tom,

Q I’m having a problem with my ‘97 Pontiac Grand Prix (3800 engine). I

have to add transmission fluid to it over a long period of time, about a gallon
or more in 25,000 miles. I cannot find any fluid residue under the car. What
could be causing this loss of fluid?

John—LaGrange,  Georgia

John,

A Check to see if the transmission is equipped with a vacuum modulator

valve. This valve operates off engine vacuum to smooth out the transition
between shifts. If the valve had a pinhole in the diaphragm, transmission
fluid would be sucked up into the intake manifold and burned in the engine.
Also, a small leak at the cooling lines will drip onto the highway while
driving or be burned off on the exhaust pipe. Finally, the transmission oil
cooler in the radiator tank may be leaking a small amount over time into the
engine coolant. Check to see if the coolant has a milky, oily, strawberry color
look and feel to it. If it does, the oil cooler is leaking into the radiator. Get it
into a transmission shop and have it checked out to pinpoint the cause of
fluid loss.

Good    luck.