Worth trying to fix water-damaged car?
Question: With the recent flooding here 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?
S.E. Answer: Ugh! You’re unlikely to have any success if you drove through anything deeper than 60 centimetres or so. Many years back, the college where I’m an auto instructor received a dozen or so new Ford vehicles that had sat in up to a metre 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. 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 labour 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? S.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-thannormal-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.
Q: My 2010 Saab 9-3 has a front-end shimmy at 110 to 120 km/h. The wheels have been rotated and rebalanced a couple of times, and it still vibrates. Any suggestions?
L.C. A: If you have returned to the same shop to have the wheels rotated and balanced, you may want to visit a different shop — one with a Hunter “Road Force” wheel balancer. Unlike the majority of balancers, this one applies force against the tire tread with a drum to simulate actual driving conditions. The machine also has a device for checking the wheel for an out-of-round condition, which could happen from hitting a curb. The correct weight is calculated and a laser line shows the correct attachment point.
Q: I drive about 150 kilometres daily, and 80 per cent of the time I am on the highway. When I get on the highway, I turn on the exhaust brake to assist when slow, gradual braking is necessary. Is using the exhaust brake beneficial in these conditions?
K.B. A: The exhaust brake simply creates some back-pressure, making it more difficult for the pistons to move. The air that would normally flow freely on the exhaust stroke gets bottled up — partially. Using the exhaust brake on the highway won’t hurt anything, and it won’t help anything around town. But it really helps when you have a heavy load, especially descending a hill, and saves the brakes from overheating.
Q: I have a 2014 Dodge Journey with a V-6 engine. The car has been excellent. However, when I have brought it in for oil changes, the dealer tells me that I should clean out the throttle body every 16,000 kilometres. I now have about 45,000 km on it, but haven’t taken their advice, because the manual doesn’t say to do it. The dealer says the cleaning will improve mileage. During the cold weather I notice a drop in mpg, but I think it is due to longer idling periods. Should I follow the dealer advice, or just stick with the manual?
J.V.
A: Follow the manual. Although cleaning the throttle body may marginally increase fuel economy, it is not required maintenance. Cold weather affects fuel economy not only due to longer idling times, but greater accessory loads such as window heaters, wipers, headlights and so on. Also, until everything warms up, the various lubricants (transmission, differential, wheel bearings and so on) are thick and until they thin out, they can cause drag. Brad Bergholdt is an automotive technology instructor at Evergreen Valley College in San Jose, California. Readers can email under-the-hood@earthlink.net; he cannot make personal replies.