Humvee Engine Knocking (yes it's actual knocking, probably)

[Mogman]

As an explanation of Mogman post, you keep cracking injector fuel lines until you find the one that does not affect the cadence/tap. The bad injector line can’t push fuel through so loosening it can’t affect the engine rhythm.

Not exactly, if an injector it is leaking which causes the cylinder to fire early creating a knock, you crack the lines one at a time until the knock stops, then you have found the defective injector.

 

[TOBASH]

Not exactly, if an injector it is leaking which causes the cylinder to fire early creating a knock, you crack the lines one at a time until the knock stops, then you have found the defective injector.

Respectfully. Not all injectors get stuck OPEN. This method I described is exactly how I found a plugged/closed injector that needed replacement.

 

[Mogman]

Respectfully. Not all injectors get stuck OPEN. This method I described is exactly how I found a plugged/closed injector that needed replacement.

Yes but that would cause a miss not a knock.

 

[Hmmwvben]

Not exactly, if an injector it is leaking which causes the cylinder to fire early creating a knock, you crack the lines one at a time until the knock stops, then you have found the defective injector.

I tried that without much success. The 400 amp alternator makes it impossible to reach cylinders 1 and 3 without removing it. I cracked all the others but its hard to isolate where the noise is coming from. The noise is very quiet when first starting at idle, goes in and out when driving, and was temporarily fixed with a bottle of Seafoam in the fuel filter when I changed it.

 

[TOBASH]

Loosen the injector hoses from underneath. Crawl under. Trust me.

 

[Mogman]

I tried that without much success. The 400 amp alternator makes it impossible to reach cylinders 1 and 3 without removing it. I cracked all the others but its hard to isolate where the noise is coming from. The noise is very quiet when first starting at idle, goes in and out when driving, and was temporarily fixed with a bottle of Seafoam in the fuel filter when I changed it.

Can you get the the IP end of the injector lines for 1-3?

 

[TOBASH]

Can you get the the IP end of the injector lines for 1-3?

When I crawled under mine, I was able to reach them.

 

[Northcross]

hello. I’m replying to the original post because I’m having a similar problem. After running for months without any problems the engine started to make a knocking noise and spitting out a lot smoke. The video below shows the knocking. This engine was replaced 20 months ago and I only drove from 4500 miles. Any suggestions what to check? From the original post some people mentioned injectors, lifter, change oil, etc.
Appreciate any suggestions.

Mine was making similar noise. Knock became quicker at RPM, blew a white cloud of smoke then lost power and wouldn’t start again.

http://imgur.com/a/8r0QRvH

 

[Mogman]

Again check all you fluids, it sounds like your transmission is slipping badly.