knocking sound at cold start up

[rva240]

hey everyone, i've got a 96 s14, stock. when i start it up from a cold start (having not ran for at least a few hours) my motor makes a pretty nasty knocking noise. sometimes it goes away pretty quick, but sometimes it will make the noise for about 20 seconds. pretty positive it's coming from the head. it won't happen when the engine is warm. and by the way the motor is a jasper, bout 40,000 on it. but it's been doing it since i had it put in. i was thinking for a while that it wasn't a big deal but i just changed my oil today and at start up the knocking sound was pretty bad and went for a while, so i figured i'd give this a shot.

and plus, my car has a cold start problem, needs at least 10 seconds of cranking before it will fire up, probably unrelated though because it came up way after the knocking sound started, BUT, the engine doesn't seem to knock if the starter has cranked for those 10 or so seconds. which makes me think maybe enough oil got circulated in the process of all that cranking to prevent the knocking. i'm not extremely knowledgable, but just a thought.

anyways, any suggestions would be greatly appreciated.

thanks, alex

[biggie]

Probably not knocking, probably the valves and/or timing chain guides before oil gets to them. Pretty standard. Not sure on the cold start, tried new plugs, new fuel filter, and other general maintainance?

[PEZi]

Pretty typical of cold starts. If you haven't ridded of the chain guides, do it. Other than that, no big deal so long as it goes away once warm.

[slidestyle69]

More than likely its potentially one or more of the hydralic lifters. while your turning it over and waiting for the cylinders to fire, Its building oil pressure thru the motor. The relavence would be the lifters work off oil pressure, if one or multiple ones are sticky then it would take the pressure longer to make em function properly.

Just like if you rebuilt your head and when you put the lifters back in and didnt bleed them, air pockets remain in them and its up to the oil pressure to bleed them for you and in the meantime, its very loud and chattery but in your case, this would be the lifter needing to be either cleaned internally with a degreaser of some kind or repalced.

[ricebike]

More than likely its potentially one or more of the hydralic lifters. while your turning it over and waiting for the cylinders to fire, Its building oil pressure thru the motor. The relavence would be the lifters work off oil pressure, if one or multiple ones are sticky then it would take the pressure longer to make em function properly.

just getting this from the top of my head...

the DOHC KA24DE have lifters with shims

while the KA24E SOHC engines had the hydraulic lifters

so is checking the valve lash on a DOHC a maintenance item, like hondas ???

hmm, my searching skills are lacking, but i found something for you to read:

http://www.nicoclub.com/archives/fix-yo ... attle.html

after you verify that the upper timing guides are gone from your DOHC engine,

then go ahead with the rest of the article (if you want to) to verify if your hydraulic chain tensioner is up to par... (or maybe just use synthetic oil ?)

edit: well yeap "valve clearance check"

http://www.nicoclub.com/FSM/240sx/1996/em.pdf

EM-30 to EM31

[slidestyle69]

Ah yea, your right about the shims. I was in SR mode right then.

[rva240]

awesome guys thanks for all the replies, i actually didn't mean to call it knocking since that term refers to something specific and i knew this wasn't knocking. anyways, good to know it's nothing too detrimental.

and by the way, any ideas about the cold start issue? after not having ran for at least a few hours it won't start until it's cranked for maybe 5-10 seconds. and of course after it's already warm it will start right up. i've done plenty of research but didn't find anything too promising, read up on the IACV a little and that seems kinda tough to get to, so it would be nice to know if it would be a worthy attempt before trying it.

and if i remember correctly, basically, from the day i bought the car it never had the issue, 4 cranks on the dot every time and it fired up. then, suddenly it wouldn't start, and i tried to find the problem for quite a while, maybe close to a month or two, and finally found that it was something broken in a little anti theft piece below my steering wheel which wasn't allowing current from the ignition to the starter, so that was ripped out and we just twisted the wires together, taped them up, and boom, it cranked! SO, ever since then, the cold start issue has been there.

it would be nice to figure it out and get it fixed, so any suggestions are welcome!!