February 2008 - Performance Zone
PUMPING UP YOUR OLD CAT
By Performance Specialist Bruce C. Mallinson
The mechanical Caterpillar fuel pump and entire fuel system is a masterpiece of engineering marvels and, when properly maintained, will live for decades. Proper maintenance of this system includes tune-ups, keeping the oil clean with regular changes, and keeping the fuel filters clean. But there is another aspect of the Cat fuel system that many mechanics are missing and that is the replacement of the wear items in the timing advance and the governor. If you are a Caterpillar mechanic, please don’t be offended by this article. I’m not questioning your ability to work on these engines – in fact, you probably know more about the internal workings of them than I do. However, we have found that these certain items, which can cause power and fuel mileage problems, are often overlooked.
Mechanical 425B and C Cats are great older engines. When properly built and maintained, these engines can produce awesome horsepower and good fuel mileage, and last a long time. Every mechanical Caterpillar engine that comes to our shop for a tune-up will have the timing advance rebuilt, the timing set, and the worn out parts in the governor replaced. At about 500,000 miles, the fly weights and the washers that the weights push against wear out. These parts are not expensive, but very technical to replace. What a difference in the sound and the responsiveness of the engine when the proper torque spring, governor spring, and other worn out parts are replaced. I know that your Cat mechanic says he went all through your engine, and that he is a great guy, but many Cat mechanics just don’t understand the fuel system.
Every mechanical Cat that has been in our shop for the past year has had worn out parts in the pump and timing advance. The owner of the truck always tells us that his mechanic had just gone through everything, but if this really is the case, why didn’t they change the crankshaft damper that is only good for 500,000 miles? Just last week we had a freshly rebuilt Cat in our shop and the old rusted crank damper was still on the front of the engine. His timing advance was rebuilt and the timing was set correctly, however there was worn out parts in the governor assembly of the injection pump. All it takes is just one worn part in this intricate assembly of parts to screw up the entire operation of this wonderful engine.
At our shop, it takes about six hours to repair and set up the timing advance, governor assembly, and to change the torque and governor springs. We now keep these parts in stock, along with the high-flow nozzles and performance turbochargers, to better serve you and minimize downtime. In one day we can take your 425B or C engine from stock to 600 horsepower and improve the fuel mileage (you need to make an appointment in advance to get in and out in one day). And when rebuilding a mechanical (or any) engine with aluminum pistons, it is worth the added expense of about $400 to ceramic and Teflon coat the pistons. Since discovering this process in 1983, a high performance engine rebuild has never left our shop without coated pistons. It is not uncommon for a high performance mechanical diesel engine to run in excess of 600,000 miles without a piston failure. You younger people may think this is low mileage, however, back in the 1970s and 1980s, 300,000 miles was the average life of a diesel engine.
You might think my ways are strange, but I have been dragging trailers around since 1971. Over the years, I have towed with small and big block Chevys, Dodge Cummins-powered pickups and a T-600 Kenworth. I currently own six trailers and four turbocharged diesel engine powered vehicles to tow them around. I never go on vacation without a trailer behind me hauling Harleys, bicycles, snowmobiles or jet skies. The Kenworth hauls an RV trailer with a garage trailer behind that and is 83’ long and has six axles, 18 wheels, and weighs 49,480 pounds. I have towed over most of the major mountains in the USA. Along with towing the trailers, I also build my own engines and have been since 1965 when I was 16 years old. The only place I have ever blown an engine was on the race track at Summit Point in Winchester, Virginia and Nelson Ledges in Warren, Ohio, where I held the track record from 1973 until 1979 in a 1966 Corvette. Back then when I raced, I always loved to hear my name mentioned as the “FTD” (which stands for Fastest Time of the Day)!
Back in my racing days, I devoted my life to building the fastest race car on the circuit and now, for the past 30 years, I have devoted my life to improving the performance of diesel engines. And yes, I have been asked often, “Why can’t you be normal?” This is why I get along so well with performance-minded owner-operators – when God was passing out the gene for “normal” he missed you, too! Welcome to the club!! Just think how boring a normal life would be. It’s a good thing that Cleesie Cummins made the diesel engine street able! Clessie really did change our lives and the Miller Family of Columbus, Indiana made it possible for him to perfect Rudolph Diesel’s invention. If it wasn’t for these few people, you just might have a gasoline engine under the hood of your semi truck.
And for any of you Cat mechanics out there that feel attacked by this article, please accept my apologies. That was not my intent. My intent is always to teach the performance-minded truck owners out there how to properly maintain their rigs for the best power and efficiency – and to help put a smile on their face when they press down on their right foot! As always, if you have any horsepower or other performance-related comments or questions, feel free to call me at Pittsburgh Power Inc. in Saxonburg, PA at (724) 360-4080 or send me an e-mail to bruce@pittsburghpower.com.