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Weird ticking noise
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=65745
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Author:  acuboy [ Mon Mar 12, 2012 1:23 am ]
Post subject:  Weird ticking noise

Hi All!

So, today I noticed a strange ticking sound coming from the engine compartment of my 2005 CRD. It sounded deep in the engine and it was regular in frequency and rhythm, it would tap away a little more than once per second. When my wife revved the engine the ticking didn't change in frequency or volume. If it doesn't change in frequency it seems like it wouldn't be the engine. But, the jeep was in park so the transmission wasn't engaged. Any thoughts?

take care
acuboy

Author:  msilbernagel [ Mon Mar 12, 2012 6:18 am ]
Post subject:  Re: Weird ticking noise

What would run independently of the engine RPM?

... perhaps the electric fan?
... or maybe your Freon is low and the compressor is turning on/off?
... could the FCV/EGR valve be cycling, attempting to move but jammed by carbon/crud?

Pretty much everything in the engine compartment runs off a belt and is tied to RPM.

Author:  maxwellp [ Mon Mar 12, 2012 8:54 am ]
Post subject:  Re: Weird ticking noise

Was it warmed up? After you drove it?
Cold ? Not driven yet?
Defrost on / off?
Outside temp?
Any and all things like this will help with a diagnoses.

Author:  acuboy [ Mon Mar 12, 2012 3:47 pm ]
Post subject:  Re: Weird ticking noise

Thanks, for the replies. I realized I clearly needed to provide more info. So, my '05 CRD has 92k miles. I bought it at 88k miles and I have no service records from the previous owner. The noise is present when the car is warmed up or cold, though louder when the car is warm. I thought it wasn't getting more rapid with the rpm's, but I was wrong. It was being drowned out by the engine noise. With the hood open it's hard to hear where it is coming from and it is easiest to hear when I put my ear down in front of the grill and cooling fan. The noise sounds like when a drummer drums on a snare drum with a brush and at idle it occurs slightly more frequently than once per second. All fluid levels are within proper range. Changing the climate control settings doesn't seem to effect it. I guess it could be anything driven by the serpentine belt? Any thoughts? I just fear something like a catastrophic timing belt failure.

thanks
acuboy

Author:  papaindigo [ Mon Mar 12, 2012 4:02 pm ]
Post subject:  Re: Weird ticking noise

Could be a variety of things but if it's something driven by the serp belt I'd expect it to change "pace" as engine RPM changes and the serp spins things faster and slower. That said with the engine off hand spin the mechanical fan just in front of the engine; that fan spins at a slow idle until the viscous clutch cuts in so it's possible it's ticking independent of the engine. If not it's worth cranking up the engine (without the plastic cover) and at an idle see if the serp belt tensioner is moving around (at idle mine is almost like a rock); if it's moving then the clutched things (viscous heater, AC, alternator - most often the alternator) have a bad clutch.

Author:  ATXKJ [ Mon Mar 12, 2012 7:39 pm ]
Post subject:  Re: Weird ticking noise

Does it change tone or frequency in drive, reverse, neutral?

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