Charge Air Cooler Leaks

[OldForester]

At our 50,000 mile service at Cummins Yakima this week I brought up an issue I have had for the last couple months and 2500 miles. That issue was a new "whine" in the turbo area that I heard when standing near the exhaust on the ISL 400. It appeared as a higher pitched whine than the normal turbo whine that we all know and cherish, and it came on suddenly. I thought perhaps I had a leak somewhere in the turbo system.

Turned out I had a bad clamp on one of the turbo CAC lines but also had some loose and missing screws holding the CAC together. Robby removed the CAC, tightened the screws and replaced the missing ones, along with replacing the bad clamp and the whine has gone away. It was like an added whine to the one we already hear.

Bringing this up because apparently some of the CAC's WRV used were welded and some were bolted together and those with the bolts work loose and occasionally need to have the bolts tightened or replaced. I did not have any loss of turbo boost -- always between 29.6 and 31.2 on a steep hill -- but I did develop the leak. So you don't know by turbo boost alone; you have to listen and feel for the leaks. Apparently the turbo can make up for a lot of leaks.

FWIW--thought I would share that with the group.

[Mike and Amy]

Old Forester..I also noticed what I thought was a new "whine" in the turbo/exhaust area. After reading your post I crawled around with a long extension and ratchet, I found 2 of the 7 turbo clamps slightly loose, I thightened them, started the engine, still whined, so decided to take it to the Cummins dealer in Oxnard just to be safe, they physically checked everything, even checked the tolerances in the turbo, they found nothing wrong, no fault codes in the computer either. It cost me $161, but I feel a whole lot better knowing all is normal...Mike

[spike45]

The Cummins Holset VGT turbos are quite the machine. They are indeed capable of pumping more air while it is leaking from the CAC circuit. Charge air cooler tank cracking is another issue that is common to midrange and HD diesel engines (18w trucks). You hear them pass you with a loud hiss or louder than normal turbo 'whistle'. The VGT adjust the nozzle ring to increase RPM and pump more air as the manifold absolute pressure sensor signals the engine ECM for more air. Holset is very good at this. A real plus in that you can run with a leaking CAC and still have standard performance. Still, best to get that leak fixed.

Check out some of my posts on the Cummins Powertrain forum for information on coolant, cooling systems, filters and Cummins midrange engines (ISB, C, ISC, ISL).