C9 losing coolant while driving

[trd_yota]

Hello everyone i have noticed a reoccurringproblem with my coach. When we use it and it warms up as we are driving it starts to leak coolant out of the overflow. I put a gatorade bottle and it lost about a quart of coolant through the overflow. It doesnt overheat at all holds 195 degrees even pulling our trailer. Only has about 7500 miles and we are worried something might be wrong. Our cat service place couldnt tell uswhats wrong anyhelp would be greatly appreciated!!!
Thank you!

[ninos]

first thing I would do is replace the radiator cap on the reservor

[trd_yota]

We did we replaced it with the appropriate stant cap. Could we have possibly gotten one that wasnt designed for the amount of pressure that the c9 cooling system creates? Its not like it runs hot at all. It runs the same even while pulling our loaded down stacker to the desert

[ninos]

I would get one at the dealer you never know

[trd_yota]

I will be going to the cat dealer to check it out then. Hopefully thats it. Man do i love this engine. Has any with a 2006 motor had to smog it yet in cali?

[Perry White]

You don't have too much coolant in it do you? You can't fill it up to the top, it has to have room for expansion. Either that or maybe head gasket gone.

[DeanLinAZ]

Well, I lived with your same situation with my 2004 Journey--330hp C7 for two years. The Freightliner Oasis Center folks in Tolleson could never figure out what was wrong. They tried new coolant caps, new coolant recovery tank and new thermostats. I finally took the coach to the Empire CAT Center in Phoenix. They put the coach on a dynamometer and finally discovered a head gasket leak at the number 3 cylinder. The clue was exhaust gas in the coolant. Several thousand dollars of labor later to replace the $180 head gasket and my Journey has been trouble free for two years and 12,000 miles. Fortunately my extended warranty paid the whole bill minus the $100 deductible and a new piston and ring set for the number three hole.

My advice is to get this checked before your CAT warranty expires. Mine was out of CAT warranty by just over eight months, but CAT did pay for the new piston for the number three cylinder--the extended warranty policy did not cover that, just the head gasket and the labor.

Good luck and go see your local CAT Service center soon.

[spike45]

One poster did have a good response in that it is possible to fill the radiator completely full to the top. Engine coolant expands about 9% in volume from ambient temp to operating temperature. It could be just expansion creating the volume needed to expand into (push coolant out).

It could also be combustion gas leakage. The simple test for that is called the 'bottle test'. Caterpillar produced a publication entitled "Know Your Cooling System". In a former life before I went to Cummins, I was a Caterpillar dealer training instructor among many other jobs at CAT, dealers, and subsidiary company. I used to teach cooling system troubleshooting using this booklet.

The bottle test is nothing more than a long rubber hose connected to the radiator fill cap neck overflow tube. The other end of the hose is immersed in a container of water. With the cooling system properly filled (usually not to the very top of the fill neck) take the motor home for a drive assuming you did use a long hose to reach into the driver area. Look for a steady stream of bubbles coming from the hose while the engine is operating under some load such as a hill. The steady stream of bubbles is indicating combustion gas leaking into the cooling system. A short stream then nothing is showing coolant expansion only.