Exhaust popping noise

[Joshf250]

Hey guys I’m working on a 2011 6.7, truck is making a popping sound out of the exhaust, injector balance rates look perfect, when injector #3 is turned off the popping stops. I replaced #3 injector and same issue continues. No abnormal blow by and no noises coming from the engine itself. When engine is revved up even the slightest bit the noise goes away. Any ideas? Maybe the injector needs a manual balance done.


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[Joshf250]

Here’s a video of the noise


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[Powerstroke Cowboy]

Does it do this whether the engine is warm or cold?

On edit: no codes either?

 

[DEEZUZ]

Exhaust valve issue.

@webb06

 

[Powerstroke Cowboy]

That was my first thoughts, and I would tend to think the same thing. It's just interesting that it stops when the injectors unplugged, or reved up a little.

 

[Joshf250]

It doesn’t change at all wether it’s hot or cold


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[Joshf250]

I even turned off all fuel and turned the engine over, no abnormal or uneven cranking.


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[DEEZUZ]

I'm finding that in having to scope alot of these 6.7s for cylinder inspections.

I bought the snap on camera that has the skinny tip that fits down into the bore and also shows 90° angle. I regularly inspect the valve conditions with it.

I recommend it to anyone that works on any engine really.

 

[Powerstroke Cowboy]

Eyes inside without ripping things apart is the best!

 

[Powerstroke Cowboy]

When the new injector was installed was the balance code for that injector set?

 

[DEEZUZ]

I even turned off all fuel and turned the engine over, no abnormal or uneven cranking.


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Don't think a cracked valve will be picked up doing cranking test. The thumping I'm suspecting is part of the combustion cycle.... It's just getting out of the cylinder for some reason... Same thing when you here intakes thumping... Either or valve is not closing/damaged and allowing combustion out.

 

[Joshf250]

When the new injector was installed was the balance code for that injector set?

Yes it was


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[Joshf250]

I'm finding that in having to scope alot of these 6.7s for cylinder inspections.

I bought the snap on camera that has the skinny tip that fits down into the bore and also shows 90° angle. I regularly inspect the valve conditions with it.

I recommend it to anyone that works on any engine really.

I will get a scope and check it out, the truck has 250k on it so I wouldn’t be super surprised if there is some sort of valve damage. I will report back with what I find


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[DEEZUZ]

What's the hours?

Hours matter more...

For example. I pulled this one in yesterday. It's popping, but out the intake...

I suspect a cam/lifter issue. The engine is toast.

79,400 miles
5258 idle hours
8040 engine hours.

This engine actually has about 270,000 miles on it due to the hours.

Miles don't mean much to me.

 

[DEEZUZ]

Like the 6.4s. I'm not seeing many of these engines make it passed 200k without a catastrophic failure(not including fuel system)

 

[Powerstroke Cowboy]

The idle hours are the killer. Diesel engine are not ment to just sit and idle.

 

[Joshf250]

The truck has 3,500 idle hours and 9,950 engine hours


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[DEEZUZ]

Yea. I'm willing to bet catastrophic failure. Cut the oil filter open. Spread the media out.

Disco ball

 

[Joshf250]

Look at the fuel balance on cyl 3


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[DEEZUZ]

I only diagnose with Ford IDS so I am not familiar but it seems it's over fueling to compensate.