Charge Air Cooler

[cjkroodsma]

Have a 2006 HR Scepter w 400ISL in a RR8S chassis. Started it up the other day and was outside when I heard a noise that was not usual. It sounded like an air leak somewhere. Upon closer investigation I believe that it is coming from the CAC (charge air cooler). This is the "Radiator" located between the AC condensor coils/oil cooler and the engine radiator. It receives air from the turbo - cools it - and sends it to the engine, an air-to-air intercooler if you will. My coils measure approximately 32W x 28H X 2-3" thick. The ends are manifolds with 4" tubes connecting to the tubing between the turbo and engine. Loss of pressure from the turbo will decrease both fuel millage and power and I assume other long term effects if not corrected. Has any one had any experience with a similar issue? What were your symptoms, problems, resolutions, repair/replacement costs and where/who did the work. My local HR dealer told me this would best be taken to my local Cummins service center. Thanks for any and all responses.

[jsabatinos]

What was the noise? Why do you believe it is the CAC?

[cjkroodsma]

Hissing/leaking air. I could actually feel the air pressure when I put my fingers between the AC condenser coils and the CAC. It was only at a given area, not high or low on the CAC and near the forward (front) side. It was blowing outward not in the normal direction of air flow through the coolers and radiators.

[Triker56]

The turbo puts air pressure in the CAC that is why you feel air coming out.
That will make you lose some turbo PSI and lose some power.

Cummins shop for sure.

[moisheh]

Leaky CAC's are not unusual. Didn't Monaco have a bunch of bad ones?? Is your CAC aluminum? That is very common. I dont think they are repairable. I knoiw there have been threads on sources for aftermarket units. Maybe Source Engineering. There are companies who specialize in CAC's. You send them the old one and they build a new unit that is much better than the original. Much cheaper than Monaco.

[BigSkyBob]

Can you spray a soapy solution in the area you feel is leaking to see if the area of the leak can be found for sure. Could it possibly be a loose or broken hose clamp?

[Rex]

You should have it pressure tested to make sure you have a leak. Could also be the connection to it or something else.

With the engine running and the fan turning, you will feel air all around the CAC and radiator as you should. Pressure test is the only way to determine a leak unless it is one you can actually see rather than feel.

Soapy solution on the core may also show something but with the air from the fan it will be hard to determine for sure.

[atomic98]

You can pressure test and I think it should hold at least same as boost (28psi). I had a ripoff shop in Carson City tell me that mine was leaking. I had them reinstall and it has no leaks. If it were leaking, you would not get any turbo boost. The obvious first thing to do is check the connections. Spraying a soap solution is good too, providing the engine fan does not screw up the results. If the rig has been in salt conditions, even by the sea, and the CAC is aluminum, it will corrode.

[CJScepter]

I had a leak on the charge side at a hose clamp, and the gasket from the turbo (o-ring) to the charge horn which connects to the first hose. The problem it caused was high egt, that was because the pressure was low and the fuel control was giving it more fuel. Under load pulling a grade the egt would go past 1200 degrees in no time, I would have to back off throttle and drive by the egt gauge. Also my pressure gauge showed about 10 pounds low at max boost.(23 lbs). I bought the coach used, and found it had a Banks Stinger Kit on it so I called Banks and they said I had a leak. I went to Home Depot, got some pipe plugs, went to the auto parts store got a air valve, like you would bolt on mag wheel. I pulled the hose off the turbo, put in the plug I had made with the air valve, pulled the hose off the engine intake and plugged that off. Put 30 lbs pressure in it and looked for leak. I found the hose clamp by listening and then the soapy spray. Put it all back together and still was bad. Thats when I pulled air horn off turbo and found bad o-ring, replaced that and now 35 lbs pressure and egt never gets to 1200 degrees. Don't know if you have those gauges but they did save my motor. A temp over 1250 for any length of time could melt the pistons or ruin the seals in the turbo.
Good luck, hope it's an easy fix
John G.

[cjkroodsma]

Thanks for all your input. It goes into Cummins on Monday. Bite the bullet, pay to play and all that stuff. Hopefully it is repairable. New part runs about 2000 to 2500. Will let you know the outcome.

[cjkroodsma]

My diagnosis was confirmed by Cummins. They found that there was oil in the air supplied to the CAC and that they said caused the silicone grommets to deteriorate and/or distort and leak. Gromments hold the tubing and fins into the CAC end caps. Apparently there is a oil leak in the turbo. Turbo will be replaced/repaired under warranty but I have to pay for a new CAC. I did my own leg work and found a Duar-lite CAC with a lifetime warranty. It was much cheaper than Monaco quoted me also. CAC is being shipped and work will be completed after parts arrival. Thanks for all your help and comments.