jumper

Just returned from 4,300 mile trip with the fiver in tow. I notice that when the engine is running 2,000 RPM or higher, and with boost approaching or exceeding 30 PSI, (e.g., a high load on the drive train), that the truck produces a sound akin to the old baseball card attached to your bicycle's forks slapping on the wheel spokes, just somewhat more metallic. It will do it in both second and in third gear (OD is too high to get to the RPM/boost with the trailer) and is not there in other conditions. The truck just turned over 225K miles and the noise is more noticeable than before I left home.

Lord I hope this isn't piston slap. I'll submit an oil analysis, but welcome any thoughts.
Thanks...

jumper

Would an exhaust leak or small crack in exhaust manifold, or maybe something similar on the intake side, give a pulsing slapping/smacking sound at high boost and rpm? I'd love to rule out engine internal issues. The motor sounds like a sewing machine otherwise.

Mexstan

Could it be the serpentine belt starting to disintegrate?

Probably not, but how about a bad tire?

gcssr

By chance could the turbo boost valve at that turbo be unloaderld at that boost level, 30 psi of boost seems high to hold and maintain, what temps are you at, at that RPM and boost,

jumper

I'm typically running a Smarty JR with its internal boost fooler in the "Performance" mode with default torque and timing, although, the problem exhibits with the factory tune as well. (As an aside, when viewing the boost from the ECM via the Torque app, the Smarty keeps the ECM reported level below 25 PSI, while my analog gauge reports 30 plus).

Temps at cylinder #3 in the exhaust manifold are at 1200+ depending on my right foot.

Now that you mention it, I recall having seen analog gauge boost levels approaching 40 PSI with the Smarty tune, no more. Maybe I've got a fluttering waste-gate. Or, maybe an exhaust or intake leak that only show up under high boost. How to diagnose?

gcssr

Check all int. duct clamps for tightness sounds like a high press leak, check all boots for tears or pin hole leaks, good luck;;

jumper

Still nothing definitive. I ordered a new turbo-pipe hot-side hose as mine is somewhat coked from the heat and another hose for the pipe-manifold connection on the cold side as it was nearly worn thru by the hydraulic lines feeding the brake booster. I've picked up the parts from the local plumbing supply to make up a turbo side plug for pressure testing the system. Will have to wait a few days till the new hoses get here to do the testing.

madhat

Sounds like a boost leak or your wastegate. Stock turbo? You could put tape around your IC joints, if it's blown off, you know you have the leak there.

jumper

How does one check the wastegate? The symptoms are a "motorboat-like" fluttering sound at 2K+ RPM and 30 PSI+ boost whilst towing or while hard in it otherwise. Absolutely no symptoms at nominal conditions. Well, other than that I've got a diesel smell at idle at times that seems newish. The plot thickens.

KATOOM

Maybe its your cape...

jumper

I replaced the hot-side turbo-pipe hose that was somewhat coked from the engine heat, and replaced the cold-side pipe-manifold hose that had a pretty bad wear spot from the hydraulic line that feeds the brake booster. Then I pressure tested the turbo to engine air system for leaks.

I made a turbo to engine air delivery system testing adapter with a rubber 4.5" x 3" plumbing adapter, a 3" PVC slip bushing that has a 3/4 pipe threaded hole, a 3/4 x 1/4 pipe PVC threaded bushing, a 1/4" pipe galvanized street elbow, and a spare 1/4" pipe male air fitting (total of about $12 from the local plumbing supply). The 4.5" x 3" adapter will tighten onto the 4" turbo inlet just fine. Turned my air compressor regulator down to 20 psi, connected the air hose to the adapter, and after few moments, pop, the 3-inch slip bushing mostly existed the rubber adapter driving the street elbow into the oil filter, denting it. I'd forgotten to fully tighten that clamp....

Anyway, a pressurized system soapy water test showed no leaks. Drive test, without the trailer but up a hill with a heavy foot on the brake to emulate the trailer, seems fine. And, I'm getting over 35 psi of boost with the Smarty Jr. Performance Tune with Default Torque and Timing settings.

I'm still getting that diesel smell at idle, so maybe the CAT has run out of lives. But, I'm getting much less smoke when getting into the throttle. I'm calling it fixed.