Why does my Duramax make a heavy knock sound?

It also doesn’t run unevenly making the vehicle shake when it’s cold (runs smooth,) but at the same engine RPM when warmed up (to normal operating temperature or at least blowing out heat from the vents) it makes a very heavy knock sound that scares me, it’s so loud. I let the vehicle cool down (it’s 15 degrees f) and tried it again 2 hours later.

Why does my Duramax 6600 engine knock when idle?

And it still doesn’t make the knock sound at all when it’s cold, which corresponds to not showing injector balance rates being far off until it’s warmed up a bit. When it’s cold I can even touch the gas pedal and raise the RPMs up to 2,500 and then back down to idle, no knock, then when it warms up it starts knocking.

What kind of sound does a Duramax diesel make?

Some 2020-2021 Silverado 2500HD/3500HD and Sierra 2500HD/3500HD trucks equipped with the 6.6L Duramax diesel engine (RPO L5P) may have a thumping or knocking sound coming from the rear of the engine. The sound is often more pronounced in the interior of the truck as it’s amplified by the transmission bell housing.

Why do I hear a knock when I start the engine?

The knock you hear from the injector is from it not doing a pilot injection cycle, which softens the detonation prior to full combustion. Only other thing i could point a finger too would be the wrist pin the the piston, which can also cause a knock.

What makes a Chevy Silverado make a knocking noise?

For the first 30 to 60 seconds after a cold start, the short-skirted pistons rock inside the cylinders and slap against the cylinder walls, sounding rather like a diesel engine. The knocking can be heard around the top of the engine, but is much louder if you listen in the front wheel wells or beneath the truck.

Why does my Duramax make a heavy knock sound?