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84 Convert
12-26-2005, 22:45
I just bought a non-running '84 Sub (see sig). It is now running, but I am concerned about a loud knocking sound (I think it is early ignition) that is more pronounced when cold and decreases as the engine warms up. There is a definite but not complete miss evident on the passenger side when I listen to the exhaust.

I have cracked all the injectors on that side of the engine, (one at a time) and have been unsuccessful in determining which cylinder the noise is coming from.

Does this fit the description of a bad injector noise or might it be something else? Suggestions?

TIA

Gregg

Lightyear
12-27-2005, 04:36
I have a fairly loud knock/chug/thunk coming from the left bank of my 6.2 'Burb. I used a mechanic's stethoscope, and I think I've narrowed it down to a noisy (collapsed?) lifter on the #3 cylinder. I listened to each injector, and they all sounded the same, so then I started poking elsewhere.

Buzz

84 Convert
12-27-2005, 19:37
mine actually sounds like early ignition when it is cold, but it quiets down once it is warmed up. I'll have to see if I can find one of those stethescopes.

Gregg

mhagie
12-28-2005, 05:10
84convert, Has someone played with the punp?
Mine had a injector knock and I found that injector lines 7&8 had been reversed, couldn't tell it at idle but as soon as a little load was applied it knocked fairly loud.
Merle

84 Convert
12-28-2005, 22:47
Idle is where I'm hearing the noise... it seems to go away when revved or loaded. It also goes away (mostly) when warm.

This truck sat non-running for 8 months prior to my buying it, so there's no telling what may have gotten sticky during that time.

This sounds very much like advanced timing (on one cyl.), but I'm not ruling out lifters, etc. yet.

Thanks for the replies.

This is the first time I've had one of these things where I had little or no info on had happened before beginning to try to trouble shoot. I feel I have a good understanding of how things work but I am lacking in actual experience. I.E. what does a collapsed lifter sound like, leaky injector etc... not that I'm complaining!

Thanks again

Gregg