Q: With the recent flooding in California, it's possible some folks will want to keep their cars even after driving them through substantial amounts of water. Some might not have sufficient insurance to easily replace their autos, for example. Do you have any tips for mechanically cleaning up and refurbishing a car that got soaked? I realize that newer, completely computerized cars are probably toast. But is there any hope for older cars with fewer computers?
_ Seth E.
A: Ugh! You're unlikely to have any success if you drove through anything deeper than 2 feet. Many years back, the college where I'm an auto instructor received a dozen or so new Ford vehicles that had sat in about 2-3 feet of water. It was a huge job to remove, dry, disinfect, clean and reinstall all the interior carpet, upholstery, door panels and other components. All the powertrain and chassis fluids were drained, flushed and refilled. Starters, alternators and such were disassembled, cleaned and lubricated. Then the real fun began: Diagnosing erratic electrical problems, noisy power steering, malfunctioning transmissions and more. It seemed the grit left behind caused more problems than the water.
As you mentioned, more sophisticated vehicles will likely have more problems, making repair attempts unreasonable. If the car was in water that went high enough to reach the instrument panel and mid-to-higher parts of the engine, it's time for the scrap heap.
However, if you're a patient do-it-yourselfer and the vehicle wasn't flooded too badly, attempting repairs could be worth the trouble. Taking such a car to a shop probably won't be worthwhile once you factor in labor rates.
Q: My truck recently began idling really rough. On a friend's suggestion, I connected a vacuum gauge to the intake manifold. It read about 13 inches. I'm not really sure what the vacuum measurement should be. Can you help?
_ Scott P.
A: Intake manifold vacuum is a helpful indicator of engine happiness, and your engine, my friend, isn't happy.
Intake vacuum, which should measure about 17-21 inches, is created by the cylinders attempting to draw in air and the throttle denying it. Lower-than-normal-yet-steady vacuum could be the result of incorrect valve or ignition timing, a giant vacuum leak, a stuck-open exhaust gas recirculation valve, clogged catalytic converter, or worn piston rings. A fluctuating vacuum reading could be the result of low compression in one or more cylinders.
Since you didn't mention performance issues at higher speeds, it's unlikely the problem's being caused by a clogged exhaust or by incorrect valve or ignition timing.
I'm wondering, when you apply the brake pedal, does it go stiff, do you hear a whooshing noise, or does the idle change? If so, the brake booster may be leaking.
Try spraying a mist of water around the intake manifold gasket-component connections and pinching off vacuum hoses close to their source at the intake manifold and throttle.
If none of that checks out, we're left with the exhaust gas recirculation valve. Removing it and temporarily blocking the exposed manifold passages is a surefire way to see if the valve was passing exhaust when it shouldn't. You'd need to next check to see if it's mechanically stuck open or being falsely commanded to do so.
