SCCS2K

Hey guys,

Pulling into a parking lot for lunch today I hear a knocking sound from the engine. It sounds like how I've heard rod knock described here (low pitch knock knock knock), except that it came and went twice, lasting a few seconds each time. I was at idle (or very close to). I didn't hear it on the five-minute drive back to work.

Is knock supposed to be a constant noise, or can it be intermittent like that? Any ideas what it was, and do you think it'll be safe to drive home tonight?

After doing a search here, I'm now panicking that I spun a bearing or whatnot... I am admittedly a "car hypochondriac", but it didn't sound like a happy noise.

Any thoughts would be much appreciated...

Dave

WalkingDrunken

The best way to go about it is if you are worried then investigate. Take it to a shop have them listen to it, and remove the oil pan and inspect the bearings. Labor should not be that terrible, and you also get an oil change out of it.

With my experience is that you can have rod knock if oil is missing and then if the oil goes back in to lubricate the sound can go very far down. I would say that it would not be easy to hear.

Chances are, just like you said, your a hypochondriac and there's nothing to worry about.

xviper

What's your oil level like?

SCCS2K

Hey guys, thanks for responding.

xviper, the oil's a little low, actually - just under halfway (between H and L). Thoughts?

xviper

This would not be the problem then. Anything in the "Xs" is OK.
Was the engine "cool". I'm thinking piston slap - not a serious thing if it stops when warmed up.
What was the rpm when it knocks? If low, I'm thinking a loping idle (very low, dipping rpm) or a bad belt tensioner.

How does it run in the rpm band above idle when just driving down the road?

SCCS2K

Hey xviper, thanks for helping me man.

Yeah, it's definitely still in the Xs...

I had been driving for a few minutes, so I'm guessing it had just hit the third temp bar.

This was low RPM - i.e. manuevering into a parking spot RPMs...say, 2500 or less. It definitely wasn't just doing that dipping thing (loping you called it?).

I've only driven 5 minutes since then, but it felt ok. I wasn't doing anything "spirited" (pretty much impossible in Santa Monica, anyway!).

Any ideas?

xviper

Not oil level, not piston slap, not loping idle. Check the belt tensioner. Open up the hood, leave engine running, tuck in all loose clothing, grab the thing the throttle cable attaches to on the throttle body and manually rev the engine while you're listening and looking at it. If it's the tensioner, it should make the same noise as you go from idle past 4000 rpm. Do this in varying rates. Rev it up slow, then try it more quickly, then try it quickly to see if you can duplicate the sound. The tensioner tends to do it work the most when the rpm changes and puts different loads on the belt. While you're doing this, you might be able to hear the noise coming from elsewhere. Try to get a read of approx. where in the engine bay it might be coming from, that is, if you can make it do it on command.

bizlipkick

i have kinda the same nosie ( which i was told was normal with forged pistons) but i took it in this morning anyway to a honda dealer- they said it ounds mostly normal but i was a smidge low on oil (half a quart, even though when i checked it last night i was a few x's up- must havebeen a bad reading) and the only thing their "master tech" thought was maybe a valve adjustment- even though i jjust got one 2 weeks ago. but they said everything pretty much sounded normal- including the slight "knock"

my .02 cents

SCCS2K

Well, couldn't make it happen on demand.

It does do this weird random "crackling" sound in the first few minutes, as it warms up. It has for a while now though. Sounds like it's coming from the valves, but I'm not sure. I've never figured that one out. I'm guessing it's unrelated.

I did just recently get a three-angle done, and a complete Ferrea valvetrain put in, but I'm guessing that's also unrelated to the "knocking".

what's the crystal ball say xviper? I really hope she's fine - I'm screwed if it's anything major again. I'm so broke I can't even pay attention! LOL

Dave

edit - thanks bizlipkick, maybe I'm just paranoid. I'm hoping so...

xviper

You shouldn't dismiss this right away. If it didn't do this before you had the head and valve work done, then it's too coincidental that it does it now. An intermittent thing like this is always a tough call. The only thing I can think of that can cause this is a lack of oil pressure during certain engine running conditions.
How old is the oil and did you change the filter the last time you did an oil change? Are you using an "acceptable" type of filter? Type and viscosity of oil?