CM870 ISX EGR Cooler and Oil Cooler

[abraham_irak]

I hope everyone is doing great. I have a question. I have a 2007 International 9400i with the Cummins ISX CM870 and I can't seem to find information on how to check the oil cooler and the EGR cooler(exhaust gases) for leakage, most of the information out there is for the CM871. The symptoms are: initial start is rough, then goes away in about 5 to 10 minutes (I am assuming is coolant leaking into the intake from the EGR); also at start, flakes of carbon (like ashes) come out of the stacks; it is consuming half a gallon of oil and one quart of antifreeze a week (roughly). No blue, black or white smoke coming out of the stacks, it has lots of power but the fuel economy is not good, currently at 5.5 MPG. I will also like to try and clean up all the parts from the intake and EGR just like Rawze did on a CM871 but I am not certain how similar the engines are. I greatly appreciate any suggestions. Thank you.

Abraham Magallon

[Rawze]

If the oil cooler was leaking, then you would have oil in your coolant.

If you suspect the EGR cooler leaking then pull off the egr pipe where it meets the intake and crank it up. See if steam and coolant come out of it.


I would suggest pressurizing your coolant system to 20-PSI with a coolant pressure test kit and find where the coolant is going.

Have you done any oil sampling and sent it to a lab so that it can be checked for coolant getting in the oil?

[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.

[Rawze]

If the tank is so old and brittle that it cracks at 20 psi, then it needs replacing. Just another thing that would put you on the side of the road without warning.