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Editor’s Note: This is the latest in a series of articles written by Bruce Mallinson for Big Rig Owner magazine. Bruce owns Diesel Injection of Pittsburgh, Inc. If you love high performance engines or just a good running truck, then you should enjoy this article and all the ones to come.

Why do some things break on trucks?  We just installed a Lipe Clutch in an FLD120 Freightliner powered by an N-14 Cummins Engine.  The Eaton Clutch was installed 120,000 miles ago and the owner-operator drives without using the clutch, except to start out.  The Freightliner had about 1.2 million miles on the odometer and the N-14 engine was rebuilt some 600,000 miles ago.  The engine ran great; however clutches just would not live behind the stock 500 horsepower N-14. 

Notice the springs are falling out of the center of the disc.

If you look at the pictures of the clutch disc, you will notice the springs are falling out of the center of the disc.  I have never seen anything like this in my 43 years of working on engines; and the owner-operator was a mechanic turned owner-operator, and they are usually pretty gentle on equipment.  After talking with the owner, he did mention that the alternator bracket has broken a couple of times, the bell housing bolts sometimes break, and the truck has a slight vibration to it.   

For those of you who have been reading my articles, you know what my next question was, “How many miles are on your crankshaft damper?”  The answer was, “I’m not sure, I purchased the truck used and all I know is the engine was rebuilt 600,000 miles ago.”  He did not know if the crankshaft damper was ever changed;  so we removed it, cut it in half on a ban saw and you guessed it - the floating plate (which floated in silicone) was locked up.  There is no way of telling if the damper is shot other than if you feel vibrations or by cutting it in half.  They are only good for 500,000 miles, and this is a fine example of the problems that worn out dampers can create.   

This owner-operator has spent more than $4,200 in unnecessary repairs because of the worn out damper on the front of his engine.  By the way, the cost of the N-14 damper is $630.00. It is the largest of all dampers on semi-truck engines.  The Cat Damper is only $490.00 and the Detroit is $330.00.  When the damper goes bad on a 3406-E Cat, it will break the Crankshaft; and the average rebuild with a new crankshaft is $25,000.00.  Why can’t I get you guys to be more aware of your crankshaft damper?  Please believe that the Teflon bearing on the moving plate inside the damper moves with every injector firing. It does wear out and contaminates the silicone. When the silicone hardens, the damper is worn out and damage is created to your truck.

It might not be the crankshaft. It could be the nose of the camshaft, accessory drive shaft, air compressor, flywheel bolts, or input shaft of the transmission. What about this?  Recently I have heard about gears in the transmission being completely stripped of all their teeth.  That’s right; gears completely stripped as though they were put in a lathe and machined off.  Could it be the damper? Torsional twisting of metal will always break it.  Something in the engine or driveline will suffer when the plate in the damper will no longer move.  Its cheap insurance to replace the damper to protect your truck, your wallet and to eliminate downtime. You know this stuff doesn’t break when your at home!

Want to squeeze the nickel until the buffalo squeals? Please don’t do it when it comes time to change the damper on your crankshaft.  I can give you several names of owner-operators that have been the victim of faulty crankshaft dampers.  The biggest victim came to our booth in Louisville last year. He had a 5-EK 550 hp. Cat Engine and it cost him 25 grand to have the engine rebuilt and a new crankshaft installed. The dealer installed the old damper because some people think the damper is good forever.  Guess what? In 45,000 miles, his crankshaft broke again. Another 25 grand was spent. 

Do you think this owner-operator is going to have to work a few more years before he can retire because of the $50,000 he spent in 45,000 miles of driving?  In 1983, I was a guest of the Cummins Recon Facility in Memphis, TN. As I was watching the crankshaft dampers being rebuilt, I asked the engineer in charge of the rebuild Department, “how often should the damper be changed?”  He said the operations manual calls for replacement every 380,000 miles; however, if he owned a truck it would be changed every 300,000 miles.  Today the dampers are NOT rebuilt, the price has been lowered on new dampers and the life has been extended to 500,000 miles.  I have worked truck shows and shared a booth with the owner and builder of the dampers and he also says that at 500,000 the damper is worn out.  I hate to keep preaching about these things. However, if you sat at my desk and talked to 45 owner-operators per day, you would be surprised at what you would hear about parts breaking for no apparent reason.   

By the way, I love the 5-EK Caterpillar Engine, and I am in the process of building one for a race truck. The 5-EK Cat Engine equipped with a Pittsburgh Power Computer, FASS Fuel System, new damper and mercury-filled balancer will give you the ultimate driving experience of a life time and 6-plus miles per gallon as long as nobody put Low Knox setting in your ECM.

I hope you have enjoyed reading this article as much as I have enjoyed writing it. My booklet is now available on the Internet at http://www.dieselinjection.net. If you would like a hard copy of our booklet, give Aimee a call at 724-274-4080. There is a $9.00 charge for shipping and handling. Just call us with your Master Card, Visa, AMEX or Discover card number and we will get one out to you. Or send a check or money order to: