LBZ: 2007 LBZ With Strange Noise

[Duramax 6.6L]

I just got involved with a 2007 LBZ pickup truck hat has a strange engine noise. The noise almost sounds like a gas engine with loose rocker, almost like a broken rocker arm. The truck idles fine with no problems but you can hear the slapping. If you rev the engine, the noise stays the same, but on the rev down the noise seems to disapear. If the truck is under a load like pulling a hill, the rapping noise get extremely worse and louder. The engine developes a skip under load.

I am thinking that this truck has a broken piston skirt, but have not heard of this being a problem with these engines. One other thought is that an injector is stuck open and this might be a fuel knock but the truck does not smoke at all.

Any ideas before I start tearing this engine apart.

 

[DuramaxPowered]

No ideas here..........Nice avatar though:spit:

 

[Duramax 6.6L]

Just got f the phone with the trcks owner to find out that the engine was started not to long ago with starting fluid, and it reved for quite some time uncontrolled.

Also idling fuel pressure is about 4500 psi, but what is odd is the balancing fuel flow rate is at -493.18 on all injectors idling. Reading takes with EFI Live

 

[Duramax 6.6L]

No ideas here..........Nice avatar though:spit:

I have quite a few more of these available to use also.

 

[bigbopper]

noise

my 06 does about same thing, possably poor fuel i add about 2gal of E85 to half a tank of diesel , fuel is not as good a quality : george

 

[rulonjj]

I had this same problem. It turned out to be a loose injector

 

[blk smoke lb7]

No ideas here..........Nice avatar though:spit:

:thumb:

Just got f the phone with the trcks owner to find out that the engine was started not to long ago with starting fluid, and it reved for quite some time uncontrolled.

Also idling fuel pressure is about 4500 psi, but what is odd is the balancing fuel flow rate is at -493.18 on all injectors idling. Reading takes with EFI Live

Some people need their can of ether taken awayse

You can eliminate fuel by disabling the lift pump if it has 1 if not all the better,disconect the fuel supply line get a jug of good clean diesel and hook a hose on the supply line and put the other end in the jug and see if it cleans up.My have to start with a compression test 1st to make sure nothing is hurt in the motor.