Whenever the engine is warm (operating temp- ie. been driven for a while) and idling, the engine of my 91 Integra RS would make a rapid ticking/slapping noise. The engine runs smooth without any ticks when started cold, and the car revs smoothly and drives like a new car (did emission tests 2 weeks ago, and passed way below the limit in all categories).

(Also, whenever I start the car when the engine is hot, the tach first rises to 2000 rpm and then rapidly drops to 200 rpm, before rising back to 750 rpm

(before changing the main relay, sometimes the engine will just cut off and die at this point, especially during a hot day))

I initially thought it was the valves, but the noise seems to be coming not from the valve cover, but to the left of it (ie. near the alternator), although it is hard to tell from all the background noise from a running engine.

What exactly is the culprit of this ticking noise? Will it compromise the performance and longevity of the car if not fixed? (I've also read in some places that it may be the wrist pin- but isn't that near the distributor?)

 

^thats a tough one... Not sure just by your descpription. Would need to hear it in person, to make a proper guess...

 

http://www.youtube.com/watch?v=6EiJnnpD-yI
sounds exactly like this, except for a B18A engine...
it might be the AC belt tensioner

 

That to me sounds like something internal. It's definitely not the ac belt tensioner. If you put your fingers on the valve cover while it's running, can you feel it? Like a tap-tap-tap...etc..?

The wrist pins are what hold the pistons to the connecting rods. It's very unusual for a wrist pin to wear out or cause any noises. It's usually a rod bearing that will start knocking.

Does the noise increase in frequency with rpm when you rev the engine?

How many km's are on the engine? Have you ever ran it low on oil?

When was the last time a valve lash adjustment was done?

 

The noise goes away when I rev it.

I don't feel any tap-tap feeling on the valve cover when its running

There are 254,000 kms on the engine currently, and I've never ran low on oil (Castrol Syntec oil changes every 4000 kms too)

The car never burns oil.

I"ve never done a valve adjustment on the car though, and I've had it since 2003...

 

First, I'd I'd check the valve lash, then do an adjustment if it's needed (I'm guessing it is needed). See if that quiets it down any.

Btw, you can go much longer between oil changes with full synthetic oil... that's what it's designed for. Might save yourself some money in the long run.

 

k this is silly... honda motors make noise, they all have weird noises that they make be it injectors ticking, valves needed adjustment, or lifters. Chances are its your injectors... but that doesnt mean theres an issue, it just a honda motor with 250 000+ kms on it.

Put your ear right up to your injectors, and one or two of them will tick really loud.

 

^I agree with some of what you said. Injectors don't tick like the noise in that video posted. You can hear the injectors ticking in the background though.

Bottom line, without actually hearing the engine in person, it's very difficult to say exactly what the noise is.

 

UPDATE:
The engine noise was caused by 2 things:
- Damaged alternator belt (forget cracking or anything- there was only 1/2 a belt left! after replacement, the new belt is running smooth, but I gotta check to see if the new belt gets damaged easily, because that will mean that the pulleys are damaged/ needs to be adjusted)
- Dirty throttle body (took some motomaster throttle body cleaner in a can from Canadian Tire, took out the intake, started the engine, pushed the butterfly valves back and sprayed the cleaner- the engine stalled for the first few times until I pushed the butterfly valve nearly all the way (engine was revving loudly at this point!). Assembled everything back together with mom's help, and drove immediately- and it was fast! And as for the noise- it reduced dramatically (its still present, but, as XNXIXTXRXOX says- its a Honda motor with 250,000+ kms)

 

^Thanks for updating us with the verdict.

Always good to find out what exactly was wrong. I've never heard of or seen an alternator belt do that before... It must have REALLY been chewed up! lol.

Glad to hear you got it fixed up!

 

lolz- half a belt was there when I replaced it- dunno where the other half went...

 

^engine was hungry fo sum rubba! :P OM NOM NOM NOM!

 

lolz... car needs a lil rubber to go down with the main course- money!
(Did a ------sheet on my car expenses- $22,100 spent on it for the past 3.5 years!)