I predict more head-gasket failures. Gas-price-driven head-gasket failures.

When fuel goes up, more drivers choose the lowest grade, even if it makes the engine knock (or "ping," for the those to whom KNOCK sounds like ping) as a consequence.
 
Knock was a big deal in the early '70s, when cheaper, lower grades of fuel came onto the market. State laws also began to curb the use of lead as an octane-enhancing additive, a practice which seems as weird to us today as spiking your dinner with ground glass to cure constipation.

Big old V-8s with 10:1 compression ratios rebelled, however, knocking like ten-pins on acceleration, particularly in the summer under high ambient temperatures and the load of air-conditioning.
 
Oil companies accordingly raised the price of higher-octane fuels as they became more popular. (Can't argue with that, though it doesn't sweeten our relationship.) So cash-strapped customers kept buying the lower grades, and their motors kept on knocking.
 
Modern engines aren't supposed to do that, of course: They're made to run on the lowest-grade fuel, which in the U.S. is about 87 octane. Onboard computers adjust for it, so there's no reason to buy 89 or 92.

In theory and design, of course. Reality is somewhat different.

I'm convinced many of the problems people have with cars are attributable to Detroit's climate. (Yes, GM also has an Arizona Proving Ground. But Arizona is not Georgia, where humidity matters. It took the 1993 switch to R-134 refrigerant—and its serious heat-transfer problems—for carmakers to build air-conditioners lean enough to make commuting comfortable in a Houston summer.) There is a tremendous loss in efficiency when an engine is breathing 100° humid air vs. 40°. Engineers know this, but I don't think they consider it important. After all, EPA tests mileage under "normalized" conditions that never change, and that's what goes on the sticker customers see.
 
So when we stamp on the pedal climbing a hill in July with the MAX AC loading not only the compressor but the alternator, we are pretty much on our own. Throw in low-octane gas that bursts into flame before the spark plug gets around to snapping, and you have KNOCK: Pistons compressing a fuel-air mixture that is already afire and expanding. Irresistible force meets immovable object. Victim: head gasket.
 
No one in my family has ever blown a head gasket. I used to replace them on other people's cars, and it always baffled me how they blew out in the first place. This is a flat sheet of (used to be) asbestos with big holes in it, and it seals the space where the hollow cylinders mate with the domed head. Lots of heat and pressure happen right there, and that's why head gaskets are reinforced with copper or steel rings that flatten out when the head is torqued down at 50+ foot-pounds. A bullet cannot penetrate a head gasket once it is installed. But a few thousand attempts to contain expanding, burning gasoline can.

My dad always taught us to back off the throttle if our engine knocked. The sound told you something was wrong, and out of respect for the mechanicals you ought to do what you can to stop that noise.

Others I knew would just keep on driving, or stab the gas pedal to "drown it out." Having rebuilt engines by hand, I could only cringe.

As people of the land, we were reared to know that machines are supposed to break. It is entirely unnatural for an invention of man to go on forever. Only the spinning earth does that. Everything else is subject to wear, tear, and time.

So I've never blown a head gasket. With any luck, neither will my wife, daughter, or son.

Posted by: Michael Rittenhouse at 07:58 PM | No Comments | Add Comment
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