I've had my '00 Prelude for about a year... its got 87000mi and as far as I know, all maintenance has been kept up to date (at least for my part). Well over the last couple weeks I've noticed a strange rattling sound comming from the engine intermittently. It seems to be most pronounced when (for example) I'm comming to a stop and I put the cutch in and the engine decelerates to idle (rpm wise). From abou 1500-1000rpm, there is a noise that I can only describe as the "slurping" sound you get when you try to sip the last bit of milkshake from your cup with a straw... other than that, it sounds like a hollow rattling (like dragging a plastic straw across a chain fence)... When i rev the engine at idle I hear it comming more from the head than anything else.

Could I be in dire need of a valve adjustment? I havent done one and I dont know if the car has had one done in its lifetime. The engine still runs smooth. I have noticed very VERY slight hesitation at random moments during the time I've owned it but nothing major. The power is still there, vtec is still there... there is just this noise that makes me cringe everytime I hear it. I decided to post on it now because within the last 2 days it has gotten about 10-fold louder... what the hell could this be? I'm off work and school tomorow so I'll be digging in and trying to see what I find... what should I be looking for? TIA...

 

edit: could this be as simple as an exhaust leak?? just throwing things out there... I do hear it noticably from the head..

 

Sounds like the infamous auto-tensioner failure. I suggest you change out your timing belt and auto-tensioner ASAP, If you can, do the manual tensioner swap. It will get worse to the point where you hear that noise all the time and it will be real loud, you can also skip teeth on your belt and start bending valves.

 

so you dont think it could be internal? i'm gettin the timing belt/tensioner this week also the tool to do the valve adjustment so hopefully by this weekend i'll know whats going on...

 

If you can reproduce it in the driveway, use a small length of hose to track down where the noise is coming from.
Stick a shooters plug in one ear to block ambient noise, then with a 3 foot piece of hose, stick one end in your open ear and have some rev and backoff the throttle. Use point the hose around till you find where the sound is coming from.
Sounds like a vacuum leak. but if it only happens when the car is in motion then I would think transmission related. but still could be a vacuum line.

ALT