Monday's rain helped swell to 2,764 the number of calls stranded motorists made over the holiday weekend to the emergency number of the Potomac-area American Automobile Association.

That total, about 600 more than the AAA logged over the Independence Day weekend a year ago, continued a pattern that has kept area towing companies busier than usual this rainy year. So far, the AAA number has averaged 681 calls a day, 250 more than last year's average. Most of the recent calls have come from motorists whose engines have stalled or batteries have died due to the rain, AAA officials said yesterday.

Once water creeps into an engine, even a good car will fail, said Allan Wilbur, AAA spokesman.

"If it's wet, school is out until it dries out," he said. "There's nothing you can do once it happens."

So what is a driver to do? The Washington area has had 10 more inches of rain this year than at this time last year, according to the National Weather Service. The water table is 1 1/2 feet higher than normal, and the likelihood of flooding increases each time it rains.

One thing to do when the rain starts, motorists are advised, is to detour around roads in low-lying areas or roads along rivers or creeks. The other: Know what to do if, despite your best efforts, your car is flooded anyway.

Wilbur advises motorists to drive at a walking pace so that water will not splash into a car's vulnerable areas. Once water reaches the center of a wheel, the chances increase that it will reach the engine, the car will stall and be almost impossible to start again without drying out, he said. If the car stalls, turn off the ignition, and, if possible, push the car off the road.

The driver who makes it through deep water should keep driving slowly, but with one foot on the brake and the other on the accelerator, for 5 to 10 seconds. This will help the brakes dry out and decrease the chance of their failing, Wilbur said.

When driving on a highway, motorists should pull off at the nearest exit if they cannot maintain 70 percent of the maximum speed limit, Wilbur said, because drivers of large trucks may not be able to see them through heavy rain and may not be able to stop in time to avoid a collision.

Pulling onto the shoulder of the road is dangerous during a storm, he added, and working under the car hood will not help if it is still raining.

Motorists should not take chances driving through high water in cities, according to Chuck Stewart, a District of Columbia traffic engineer, because manhole covers often come off and roads sometimes cave in before the driver knows what is happening.

"You should always back up and take an alternate route," Stewart advised.

Once the car engine is flooded, most service stations can do what they call an engine flush, according to the AAA. An engine flush includes cleaning, draining and flushing the engine, wiping off all electrical or electronic circuits, and clearing out sand or silt, and may cost about $150, Wilbur said.

The next step is to wait and see if there is any permanent damage, which may include rust and corrosion, Wilbur said. A driver can rustproof the body of his car, but there's nothing he can do about rust in the engine, he said.