Hollow noise at air intake

[02bymorris]

I had #6 (broken) push rod replaced on my Duramax a week ago. Since then, I hear a hollow noise in cadence at idle that was not noticeable before. Any suggestions what the noise could be?

[CleviteKid]

Not being very familiar with the Duramax :( I can only speculate that something between the turbo compressor and the cylinder heads is not fastened down tight. If it was disturbed, the exhaust between the cylinder heads and the turbo turbine might also have a loose connection.

Any other ideas from those who DO know the Duramax??

Dr. Lee :cool:

[DmaxMaverick]

Your problem is probably not a "Duramax" problem, but a service problem.

There is a bunch of plumbing under the hood. Replacing one pushrod would require the removal of most of it. Replacing all those pipes isn't like a jigsaw puzzle. The coupling hoses that connect the pipes will allow quite a bit of "misallignment" to happen. Check that all the pieces have sufficient clearance to the other parts around them.

I had a similar occurence when I removed/replaced a pipe. It was clear, but close to the steel fuel line at the fuel filter. Over about 10K miles, the steel line had peened a dimple into the soft aluminum intake pipe. All superficial. Loosening of the coupling hose, a slight rotation of the pipe, and retightening of the clamp solved that problem. The pipes are not supported by clamps. They rely on the couplings to maintain them, hanging free in space.

Best way to check would be to wiggle those pipes. If one is pretty close to something, it's probably causing the noise. Those huge aluminum pipes sure can resonate a noise.

Similar noises are common on 6.2L and 6.5L engines. Just about anything coming in contact with one of the injector lines would sound off in cadence. Easy fix. You just need to locate the contact point and steer it away. Not a problem with a Duramax, though. The fuel lines are not pulsed.

Happy hunting.