Auto Service World
Feature   April 1, 2002   by Rick Cogbill a.k.a. Slim Shambles


My Dear Bean.

No matter how hard you try, there is one element of the automotive trade that you can’t get away from, and that’s free advice. I’m not saying that we can’t afford to do a little pro bono work for our customers (for you non-lawyer types that means free work), but if we got paid for every problem we solved during soup at a dinner party, a lot fewer technicians would be leaving this trade.

However, I have to be honest and admit that I enjoy solving some particularly difficult mystery. Like my literary hero, Sherlock Holmes, there is a certain thrill when “The hunt is on!”

Such was the case when Woody brought in his engine for our inspection. “Open the hood,” I commanded, standing by the front of the pickup. “Let’s take a look.” Woody went to the back and opened the tailgate. “This ain’t my truck,” he said. “It’s my buddy’s; my engine is back here.”

We peeked into the box and there, in a dozen pieces, was Woody’s tired mill. The heads and intake manifold of the Ford 5.0 litre fuel injected engine were off to one side, and the engine block was propped up with 2x4s like a patient on an examining table. “Here’s the problem,” he grunted, pointing to cylinder #8.

Like a gaggle of geese jostling for position, we all crowded around for a look. The edge of the piston in the offending cylinder was melted right down to the top ring land, and the cylinder was badly scored. All the other pistons looked fine. “Okay, all you hot-shot detectives, how come just this one burnt up?” Woody asked, knocking the ash out of his pipe on the bumper.

Basil popped an all-day sucker into his mouth to help him concentrate. Tooner buried himself in a cloud of cigarette smoke, while Beanie stuck his hands in his pockets. Clearly, this was beyond his area of expertise. “What do you think?” I asked Basil. He pulled the sucker out of his mouth and waved it in Woody’s direction. “I’ll tell you what I think. To start with, your truck runs on dual-fuel, propane and gasoline; you have recently replaced the head gaskets and the piston wasn’t like that then; it has been running poorly on gas, but propane was okay, until last week, when cylinder #8 lost compression, which is why you took it apart.”

Woody almost dropped his pipe. “You can tell all that from looking at my engine?”

“No,” said Basil. “Your wife called to tell us you were coming up. She told me the whole story.” He pointed his sucker at the melted piston. “Slim, what does that remind you of?”

I had an idea where he was going. “It reminds me of a carburetted engine on dual-fuel, if you switch to propane before running all the gas out of the carb. Sometimes the two fuels will catch fire and melt the venturies into a puddle of aluminum.” Tooner climbed into the box to examine the intake manifold. “Look here,” he said, “the runner to #8 is washed clean, probably by gasoline.”

Beanie was puzzled. “But this has port injection; how could gasoline get into the intake manifold?”

Basil pointed to the vacuum tree on top of the upper intake plenum. “Through the vacuum line of a ruptured fuel pressure regulator,” he surmised. “Since the runner to #8 is lowest, the gasoline would pool there and be sucked into the cylinder. The extra heat of the combined fuels is too much for the aluminum pistons.”

Woody stared in disbelief. “You mean a bad fuel pressure regulator ate my engine?” I slapped him on the back. “Maybe you should have looked a little sooner into why your truck ran so poorly on gas. Could have saved yourself all this expense.”

As Woody drove off dejectedly, Beanie was in awe. “That’s amazing, Basil.”

Basil crunched his sucker one last time. “Elementary, my dear Bean, elementary.”

(Thanks to John Cornett-Ching of Summerland Auto-Tech in Summerland, BC, for this month’s technical problem. If you’ve got a good story to tell, e-mail Rick at

About The Writer

Rick Cogbill is a freelance writer living in the Okanagan valley of Southern British Columbia. A licensed technician with over 25 years in the automotive repair industry, including ten years as a shop owner, Cogbill creates his comic scenarios with Slim, Basil, Tooner, and The Bean out of actual case histories. “What you have just read is true,” drawls Slim Shambles. “Only the names have been changed to protect my hide!”

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