CM870 ISX EGR Cooler and Oil Cooler

[Chamberpains]

How many miles on it? Has it ever been apart for inframe or head work? How many gallons of oil is used in your normal oil change interval? How long are your oil change interval? Any small oil leaks? How many?

Have you ever checked you fuel metering and timing actuators? They're the same as on the cm871 and Rawze has instructions on checking them. This may be the cause of the rough running on start up.

Also pressure test your charged air system. All the piping, clamps, CAC, intake gaskets. Check that little rubber hose that connects your intake line to your air compressor. Its right behind the air compressor about 3-4" long. They split frequently. A few small leaks in the charged air system adds up to big fuel mileage loss and excess soot out the stack.

You can buy a full coolant pressure test set on ebay or Amazon for $60-$100. Don't be surprised if you crack your coolant surge tank going up to 20 psi. The old black plastic gets quite brittle the older they get. Start with only taking it up to 15 psi and leave it sit there for an hour if your checking for coolant system leaks. I believe the cap is only rated at 15 psi. I run 0 psi in mine for 5 years now (I cut the rubber gasket in the cap slightly so it never seals but doesn't slop coolant out either) so i cracked my tank just putting 10 psi in it.

If you need to go deeper and pull the engine oil pan to check for liners leaking, there should be an adapter in most pressure test kits you can disconnect the large line at the bottom of the surge tank and clamp the adapter in and pressure test up up to 20 psi. Clamp off the small return surge line.