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Cummins ISC Diesel Engine Repair

After the Cummins C series (Bosch fuel injection) diesel engines did their time in our fleet we were introduced to the ISC electronic model. A high pressure fuel accumulator supplied the injectors using a distributor pump. There were a few of these “CAPS” pumps that failed but that was over a long period of time.

They were very costly to replace but over 10 years is not a bad record. The other failures were the fuel transfer pump and failed injectors. These repairs are to be expected when accumulating mileage on a diesel engine. As the saying goes “nothing lasts forever”.

Every Video Tells A Story

The video below shows you a repair we did which was an unusual problem involving the valve train. A valve spring broke and caused the push rod to bend and break the lifter. You can just imagine if this engine was humping along at 2000 RPM and how fast this failure would occur.

As you can see in the photos the damage has been done. The camshaft had to be replaced along with the lifters and valve springs. The head needed repair so we sent it out to the machine shop. To play it safe we changed all the valve springs. The lobe on the camshaft got the worst of the failure.

The front of the engine had to be disassembled to remove the camshaft. This invlolved removing the vibration dampner and the timing gear cover. The lifters on these engines have to be suspended using wooden dowels.

With two dowels for every cylinder they have to be tied together with elastics to make them tilt at an angle and secure them in the lifter bores. They sit on top of the cam lobes…. so to remove the cam the lifters can not be allowed to drop down and make contact or else the camshaft would jam up while trying to slide it out from the front of the block.

It was 1999 when we first started buying buses with the ISC Cummins. They proved themselves well over the years along with reliability and great service from the local Cummins dealer. Although the price tag was around 4,000 dollars to replace the CAPS assembly it was not until after 2010 when they began to falter. The up time with very few failures made this one time expense well worth it.

If you’ve had any experience with the Cummins ISC please leave your comment below. It would be nice to see others share their information here. Also, if you want to hang out with other diesel engine minded individuals join the mechanicshub.com community. This is where you can help others and ask questions or just hang out.