Driving through deep water not worth risks
Question: On the news, I’ve seen many cars driving through flooded areas. I’ve always thought that cold water hitting a hot engine block could crack or warp the block. I’ve also thought that the water could short out many of the car’s electrical components. Are my concerns justified? Is there a rule of thumb as to how deep you can safely drive your car without damaging it? H.J.
Answer: I also wonder how some of those vehicles will fare later. Driving very slowly through perhaps four inches of water is the limit I would subject my car to. My main concerns at this depth are thermally shocking a hot catalytic converter, possibly fracturing its fragile honeycomb core, and possible damage to brake rotors, should they be at an elevated temperature.
Water deeper than this or a wave generated by another vehicle can splash upward toward transmission and differential vents, a split CV joint boot, a low-slung alternator or starter, or an air-filter pickup tube. Gritty water entering a lubricated mechanism will certainly accelerate wear.
I’m not certain if some water entering the alternator will create a short circuit, but it certainly isn’t a good thing to try. Water in a non-operating starter isn’t a big deal other than possible grit left behind. A wave of water up into the air box and filter could cause severe engine damage if it gets past baffles and the throttle and enters the engine. The ingested liquid isn’t compressible, so really bad things happen when the pistons try to squeeze the airwater-fuel mix.
I don’t think damage to the engine block is highly likely as the hotter parts of most engines are typically up high, with the exception of Porsche, Subaru and Toyota BRZ horizontally opposed engines. Most other auto parts, including electrical components and connections, are pretty well sealed, making damage possible but not that likely.
The bottom line is damage is possible, and unless it’s an urgent situation to get through the water, it’s best not to do it. And if it’s salt water, you might as well just throw the vehicle away afterward.
Q: I’ve noticed the outer edges of my front tires are wearing prematurely. The car doesn’t pull, the steering wheel is straight and the tires are full. What could cause this? M.E. A: You mentioned two symptoms of a wheel-alignment problem, but there can be two more that are less noticeable. Also, good job on keeping the tires properly inflated.
Camber is the inward or outward vertical tilt of the tires/wheels, as viewed from either front or rear. Straight up and down seems like an obvious attribute, but many vehicles are set up with slightly positive or negative camber by design to help with turning geometry. If excessively positive (tire leans outward at the top), this can accelerate outer edge wear. Vehicles that are driven aggressively on winding roads often benefit from camber being adjusted (if possible) to the negative end of the specification range, and frequent tire rotation. Improper toe (tires are non-parallel as viewed from above or below), can scrub rubber away more visibly on the tire edges than the centre. Assuming you’re rotating the tires regularly, an alignment check is recommended.
Q: Do you recommend having a fire extinguisher in one's vehicle? If so, what size and type? And how should it be stored?
G.B. A: We have not seen many car fires since the demise of carburetors, which would occasionally ignite from engine backfires. Nevertheless, if you are someone whose motto is better safe than sorry, get a dry-powder extinguisher sold for automotive use. Keep the extinguisher within the driver's reach.
Q: I own a 2005 Toyota Camry with 70,000 miles. When starting first thing in the morning smoke comes from the exhaust for a minute or less. The balance of the day it is OK. It does not seem to be losing any oil. Please advise.
S.R. A: Some oil is probably seeping past the valve stems and into the combustion chambers. Two typical causes are worn valve guides or valve stem seals. It only takes a couple of drops of oil to make visible blue smoke before the catalytic converter reaches operating temperature. Brad Bergholdt is an automotive technology instructor at Evergreen Valley College in San Jose, Calif. Readers may send him email at under-the-hood@earthlink.net; he cannot make personal replies.