Auto Service World
Feature   February 1, 2001   by Rick Cogbill a.k.a. Slim Shambles

The KSB and the Cold War

Long-Haul Herman was used to getting his own way. He made that obvious when he tossed the keys to his '92 Dodge 4x4 on the counter. "Check out my glow plugs, Slim. The old truck ain't starting so good...


Long-Haul Herman was used to getting his own way. He made that obvious when he tossed the keys to his ’92 Dodge 4×4 on the counter. “Check out my glow plugs, Slim. The old truck ain’t starting so good.” The toothpick in his mouth waggled from side to side. “I’ll be back tomorrow.”

I looked out the window at his 3/4-ton pickup with the 5.9 litre turbo-charged diesel engine. “I don’t think the Cummins diesel uses glow plugs, Herm. Instead they…” But I was cut off.

“I drove rigs for thirty years,” growled Herman, gripping the counter. The coiled cobra tattooed on his bulging forearm rippled dangerously. “Every diesel I’ve ever owned had glow plugs, an’ I know what happens when they don’t work!” His eyes narrowed. “Figure you can handle this?” he asked.

“No sweat,” I replied hastily, wiping my brow. Herm grunted and rumbled out the door. This was going to be interesting.

Tooner pulled the truck inside and got to work. The complaint was poor starting cold and lots of white smoke. “Hey,” he said, after a quick inspection. “There’s no glow plugs on this engine.”

“I know,” I answered. “I tried to tell Herman that, but he wouldn’t listen.” I pointed to a pair of large solenoids on the left inner wheel well. “Cummins uses an Air Intake Heating system to warm up the incoming air. These solenoids supply battery voltage to the twin heating plates in the throttle body assembly.”

Tooner tested the solenoids, then did a resistance test on the plates. “Seems okay here,” he said. The air charge temperature sensor that governed the system tested fine as well.

Glancing at the clock, Tooner put down his tools and hollered for our apprentice. “Beanie, get your backside over here and start surfing the electronic repair manuals; I need some more info on this cold-start system.” Then he sauntered off to find a cup of coffee. Tooner could fix just about anything, but he and computers just didn’t mix.

The Bean, on the other hand, was more at home in cyberspace than anywhere else. And it wasn’t long before he appeared with a handful of printouts. We spread them out on the coffee table.

“Besides the Air Intake Heaters, there’s also a Fuel Heater, located just above the fuel filter,” announced Beanie. “Says here that a defective fuel heater can cause hard starting, miss-fire under load, and blue or white smoke from the exhaust.”

Tooner scratched his chin. “Hmm, could be the problem.” But it wasn’t. After verifying that the circuits involved were working properly, we were no further ahead.

At that point Basil entered the conversation. “Have you checked out the KSB circuit?” he inquired.

Tooner was mystified. “What’s the KGB got to do with this?”

Basil closed his eyes and sighed painfully. “The KSB solenoid is a valve on the side of the injector pump,” he continued, “that is energized when the intake manifold temperature is below 15C. It prevents venting of the injection pump pressure regulator, causing injector pump pressure to increase at idle. This advances the injection timing for better cold-start operation.”

“Cool,” said Beanie. “A diesel with a choke!”

We put the truck outside to cool down, and when we tested it later, discovered that there was no power getting to the KSB solenoid. A faulty air temperature switch in the intake manifold proved to be the culprit, and with a new one installed, the truck started and ran beautifully. But now I had a problem. Even though we’d fixed the truck, Long-Haul Herman would not take kindly to being proven wrong.

The following morning Herm came in to pay his bill. His toothpick was still as he looked over the invoice. “Repair glow plug circuit: labour time and one sensor,” he read with a pleased look on his face. The toothpick started to move again, which was a good sign. He plunked his credit card down on the counter.

“Ring ‘er up, Slim,” he boomed. “Nice to see you boys know how to take a little advice from someone who knows.”

I kept my thoughts to myself as I ran his card through the machine. The bill is paid, the vehicle works great, and the customer is happy. What more could you ask for in this business?

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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