i have a 93 civic si w/d16z6
i got it about 2 or so weeks ago, and recently it has had a knocking sound when in idle, but it goes away when revved up and it doesn't do it 100% of the time more like 70-80%. we've tried adjusting the valves, checking the timing, and running sea-foam to see if it might be a sticky lifter or something. still no luck. anyone know what might be causing it? thanks

 

seafoam is a BAD thing

EDIT:
https://honda-tech.com/forums/showth...hlight=seafoam
P.S i know your new (WELCOME TO H-T) but we do have a search engine.
https://honda-tech.com/forums/showth...+knocking+idle

 

The first step is to localize the source of the noise. Try using a short length of rubber hose pressed to your ear and various part of the engine (=ghetto stethoscope). Do this procedure from both above and below the engine.

 

that or a long screwdriver put the metal end on the motor and the handle to your ear.. works for me!

 

maybe just the begining stages of a rod knock

 

Do a compression check and possibly a leak down test to eliminate valves and rings and walls. If that all checks out ok, check oil pressure. If you have low pressure then you've got excessive clearance in your crank/rod/cam bearings and thats where your problem is and will do nothing but get worse, eventually. and yeah the screwdriver trick works as a stethascope to help find the knock!

On another note I've actually seen Smog results done before and after a sea foam top end cleaning (cleans carbon deposits from chamber etc...) and it brought NOX down like 6-700PPM!! pretty good!!

 

i just took it out for a little bit, it knocked a little after warming up for a bit. but after i got back home from driving it around it sounds a lot worse, you can clearly hear it. we don't know what kind of oil it has in it right now so we're gonna change it out tomorrow and see if it helps...hopefully. otherwise i dont know what else to do

ill check where the knock is tomorrow after the oil is changed

 

I doubt changing the oil is goin to make it go away.

 

ill try to do the compression test tomorrow too

 

Yeah try that!

 

alright i didnt have time to do a compression test today, but probably will tomorrow. on the other hand i tried pinpointing where the knock was coming from and i got nothing from it, even used a stethoscope and all. could it possibly be just the way the engine is? i mean its not a super loud knock, just one thats noticeable

 

No, there shouldn't be any sort of knocking Noise at all! you really should do a good diagnosis with a compression test, leak down oil pressure etc... that's how your gonna find your problem

 

naa dood, don't drive it as well, you adjusted the valves already, to what gap?

 

well i narrowed it down to the number 1 cylinder, ive driven it a little since then. it sounds live its one of the valves, so next weekend or something im taking off the head and seeing what needs to be done. the gap is .007 and .009 or something like that. its to specifications though

 

How did you determine that the knock was coming from Cyl #1? Does this mean you hear the noise coming from the side of the block?

 

i disconnected the power to each cylinder by pulling each spark plug. the noise stopped when every cylinder but #1 was running. and yeah used a stethoscope and it seems to be coming from the side the most

 

i ran sea-foam once...... my car backfires in between gears under very high revs ((mashing out on the em1)) and from 2nd to 3rd after sea-foaming i blew the welds on my cat. hahahaha **** sea foam

 

yeah used it once....never again ha

 

I would think that a knock from the block would lead you to removing the oil pan to inspect the #1 piston bearings.

 

well the sounds coming more from the headers/intake manifold so thats why i was guessing possibly valves. plus if it were something with the bearings wouldnt it be noticeable throughout the rpm band?

 

I guess that you could say the same thing for valve noise. In addition, might the noise actually be coming from the header or IM? Nonetheless, I am very interested to know what you find.

 

i thought that as well, but im not positive. im no expert in valves nor rod bearings. but ill post what i find though when i take it apart probably next weekend

 

I am very interested as my 00 EX has a similar knock or tick only at idle. At rpm above idle or while the car is running, the engine sounds and runs perfect. My valves were recently adjusted to spec, and the noise also seems to be coming from around the block or header. I have ruled out the power steering pump, A/C compressor, idler pulley, and the alternator. I do occassionally hear a little bit of exhaust pipe A rattle at 1500-2000 rpm, so I was thinking the sounds may be related. Perhaps a loose header? However, I can't detect any free play in the header. I'm stumped, so I hope your experience gives me some new insights.

 

You guys with the seafoam problems are amusing (by saying it sucks)... i've ran it many times in different cars and never had a problem. Have you guys been changing the oil soon afterwards and changing the plugs?

 

well turns out you were right. it turns out the be the rod bearing, or i guess theres a possibility that it could just be the wrist pin too. but ive had 2 people look and listen to in (2 mechanics) and they both think its the rod bearing. so right away stop driving it if at all possible, it will only cause more and more damage if it is the rod bearing. get under the engine and check it out. depending on how much damage there is you might only have to replace the bearings, but if theres too much then you'll have to end up getting the crank re-ground and then most likely oversized bearings installed. get everything checked out if you can. im taking care of things this weekend hopefully so we'll see how things go