Rep Power: 0

2004 Civic Ex; automatic; 40,000 and a few hundred miles.

Whenever the engine passes through the 800-750 rpm (or if it sits in it) a rapid clicking / tapping sound occurs.

The severity of it seems to be dependent on the outside temperature. At night it will frequently not happen if it's sufficiently cold.

Here's the part that scares me, if I drop it into neutral and drift into a stop ... nothing. If the noise occurs and I switch it to neutral, poof its gone. But, if I crank up the a/c or anything that should increase load on the belts (not certain how inter-linked the belts are on this car) it's not the same.

In general, performance (especially low gear acceleration) is poor and there's a sort of humming feeling. It feels heavy, like I'm towing a trailer.

NOTE: The a/c is always on? Even when I turn it off there's a slight flow at the appropriate setting ... is this normal?

Status
Oil, Coolant, and Trans-fluid = good
Air filter = checked clean, 10k on it
Inspected at 32k at a dealership, found to be in great condition
Spark plugs = unknown status

I have not checked the valve clearances, but I would expect that to be consistent not under such specific conditions. I have not inspected the EGR valve for carbon gumming. Have not examined PCV valve.

The vehicle did recently go through a considerable (4 inch) fall at 65mph prior to this problem appearing. I haven't ruled out a suspension vibration issue, but I would expect that to be fairly constant if it's being triggered by engine vibration.

I have not inspected for exhaust or vacuum leaks (wouldn't know how to go about doing such, may have to do some reading). Upper portion of the exhaust manifold isn't spitting out hot air.

Concerned that it could be an issue with the timing belt tensioner. But at 40k I wouldn't expect that to be a problem just yet. Belt system 'should' (according to manufacturer) be good until post 100k.


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If it would be helpful I could probably manage to produce a recording of it if my description isn't quite adequate.


Thanks!

[edits: grammar corrections, **** about that]

 
Rep Power: 813

either a valve adjustment is needed, or you have one or more torn engine mounts. they can cause big problems as ive found out and tend to break quite easily.

 
Rep Power: 0

Thanks!

I'll cross my fingers and set the valves saturday. Sigh, there goes my day.

 
Rep Power: 0

Haha, neither.

The heat shield on the catalytic is flopping around like a bitch, I squatted down and watched a friend drive it around a parking lot, and there it is dipping and catching air. I'd imagine it could be wrecking temperature havoc with sensor after sensor.