11-17-2010, 08:01 PM
Compression Ignition Addict
Join Date: Jan 2010
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Mystery knocking sound...
Ok guys, I have a real head scratcher here!
- Loud knocking noise coming from engine compartment ONLY when accelerating
- No knocking sound when revving the engine in neutral
- No knocking sound when traveling at any speed while in neutral or clutch engaged
So basically, the only time it'll knock is when I'm accelerating in gear, whether it's a 5mph, or 30mph. But as soon as I let off the accelerator it goes quiet.
- Bent / bad pushrod - but it rev's and idles just fine at all times as long as I'm not moving
- Bad injector - possible, but doesn't really seem to fit
- Bad U-joint - My steering was acting VERY weird earlier in the evening prior to the knocking - but still doesn't make sense that I can go down the road at 30mph and it'll ONLY knock if I'm accelerating. Lay off the gas and the knocking stops.
- Tranny - shifts smooth as ever with no noticeable decline in performance
Any ideas? These symptoms just don't make any sense to me, but something is definitely very wrong under the hood!