Knocking noise
Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
Injectors aren't high on the suspect list with yours. If it still knocks on decel, I'm leaning more toward valves or something more serious. Sorry.
Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
That depends on the severity of the problem. Slightly loose injectors (50 - 75 inch/pounds torque on the injector bolts) will make all kinds of knock, lose some ICP, but not smoke too bad. A Cody test may reveal this, or you can just go in and check the torque. Checking the torque is a lot of work to do if you don't have O-rings on hand just in case. Does the knock go away on decel?
Junior User
Joined: Aug 2014
Posts: 71
Likes: 0
I tried to see on the way home after I read that. I didnt notice a lack of knock but this thing is pretty noisy. I gotta listen REAL close to identify it in the cab. Is it common to loose an O ring and not an injector? If im going to change em Id like to upgrade them and from my reading it seems you cant just upgrade one at a time. No sense in dumping a grand or two if nothings wrong. Ill be doing a cody test on my days off, thank you for the input. Im sure this is just coincidence but this all started after I cleaned my intercooler tubes. I checked for leaks and didnt find any just seems awfully strange. . . . Before I messed with the intercooler system I changed the glow plug relay and everything was great for about a month.. . .
Junior User
Joined: Aug 2014
Posts: 71
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Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
Decel is any time the wheels are pushing the engine, instead of the other way around. The injectors shut off with decel, so if the knock stops - the knock came from the sticks.
Bad O-rings on good injectors happen, but the frequency of just the O-rings going bad and the injectors are OK... well... not a good track record there.
Bad O-rings on good injectors happen, but the frequency of just the O-rings going bad and the injectors are OK... well... not a good track record there.
Junior User
Joined: Aug 2014
Posts: 71
Likes: 0
got it plugged in to a machine. Says #8n cyl is acting up and you can clearly hear it on the passenger side. is this what I need? Alliant 'AE' Injector - Riffraff Diesel Performance
More Turbo
Joined: Mar 2003
Posts: 578
Likes: 1
From: Green Bay Wi
My brother in law had this same issue. Looked at almost everything come to find out it was the flywheel the whole time. It was cracked. It would nearly go away at high RPM and come and go at certain RPM's. Most likely Harmonic. The crank bolts ended up getting trashed as well. So if it sounds like its in the bell housing it is something you may want to look at. You can get one of those scopes now real cheap at harbor freight.
Junior User
Joined: Aug 2014
Posts: 71
Likes: 0
hotrodfeguy, that has got to be the most discouraging thing I have heard yet. I feel a vibration on the floor board when im on the highway and cant find the source. The 'knocking' sound is clearly somewhere on the passengers side. You can barley hear it on the drivers. . . . Your freakin me out! Whats this scope you speak of? what codes did your brother in law get. Ive got
Intake air temp. sensor circuit high input
Cylinder 8 contribution/balance fault
ICP pressure above/below desired
Injector circuit/IDM codes detected
I was thinking about changing the IPR valve. . . Im gunna go revv it while its sitting and see if that vibration shows up.
Intake air temp. sensor circuit high input
Cylinder 8 contribution/balance fault
ICP pressure above/below desired
Injector circuit/IDM codes detected
I was thinking about changing the IPR valve. . . Im gunna go revv it while its sitting and see if that vibration shows up.