Monday, April 06, 2009

Cummins Diesel Repair - ISC Model

This particular Cummins diesel repair was necessary because of an indirect code that was finally traced to the camshaft endplay. There are 2 sensors installed to the backside of the timing cover just below the top drive gear (the 2 black round shaped sensors are visible to the right of the cam shaft bearing bore). One is the camshaft position sensor the other is the engine speed sensor.

The camshaft has been removed as well as the cam gear (above). You can see the tone wheel that the sensors read and send a voltage signal to the engine ECU. When there is a problem with these readings an engine code appears and a driveability problem arises. There is a specified air gap between the cam gear and sensors, if that gap is not maintained an inaccurate signal is produced. This is typical for most electronic diesel engines and care has to be taken when handling these components.
To remove the camshaft the rocker arms and shafts must be removed first. The wooden dowels act as holding devices that jam into the solid lifters that ride on top of the cam lobes. Once the dowels are installed elastic bands are used to hold them secure while removing the camshaft. This saves a lot of time not having to pull the cylinder head.

The camshaft endplay was excessive which caused the sensor problem/codes to become a regular occurrence. The first step we took was to change the sensors, this cured the problem for several weeks but the fault always came back to haunt us. The camshaft showed signs of wear on the shoulder where the gear sits and the cam lobes as well. There is a thrust washer that goes between the gear and the engine block to help with endplay movement.

If you have to do this job in a Thomas ER Pusher Bus you will have to remove the rear engine mounts and lower the engine enough to get the rear pushrods out of the engine. The solid floorboards above are not designed to allow the pushrods enough headroom for removal.
The cam gear has to be heated to 400 degrees Fahrenheit to install back onto the camshaft. We elected to replace the gear as well as the camshaft. If you are a Diesel Mechanic this is a Cummins Engine repair you may have to go through one day. I hope this mechanic info has helped you understand the procedures involved in this operation.






5 comments :

Anonymous said...

We've got 14 ISC engines and I've seen this problem before. If your lucky one guy in the shop has small arms and hands and ca reach between the Caps and the engine and change those sensors.

Anonymous said...

2006 Ram3500 cummins 5.9l. Intermitent cam sensor dtc that does not occur at idle but happens regularly at 1500rpm or more. graphed cam sensor and spikes intermitently. engine has 240 oookm and cam end play may be cause. new sensors and wiring have been checked... may have to remove timing cover to check end play. thanks for this post.

Richard. said...

A simple high school certificate coupled with technical training certification will make one eligible for the job of diesel mechanic.


diesel mechanic

Anonymous said...

on that ISC doing that you did a cam replacement on what size are the wood dowels

John Whelan said...

The wood dowels are 1/2 inch and 12 inches long.