91 S13 knocking sound in engine

[mchkc240]

Hello~ I just bought a 91 240sx and i realized that sometimes when it idles the engine would starts to knock. But when I am driving the engine is always smooth and runs normal. The compression on this stock ka24(123k on it) is good. Last owner told me it could be the timing chain in the engine? So does anyone have the same problem? So how could I fix it? Thanks

[Kittychubbs]

wut dah!??

the last time my engine starting knocking its when it went boom-boom!but, mine didnt drive at all normally after that, so i did a swap but urs does , so it must be a lil thing like the chain fix it adjustment and thats it.

[mchkc240]

Thanks~ So how could I fix it? I am still waiting for my service manual

[Kittychubbs]

go to autozone and ask for a belt chain tool (rachet) and then u leave a deposit and u go home, in the front of the engine there is a lil nut u turn so the belt sags then just slip it off and install the new one then turn the nut back to place and make sure they are tight. then return the tool and get ur money back.If that doesnt help check ur oil too it might me too burn or very low,get full synthetic it should help too, change spark plugs.

dont race it or force it yet till the knockin goes away.hope that helps maybe sum other members can help out too.

[dkdeleon68]

where is the sound coming from, the top or underneath the motor?Hopefully its from the top, if it is from the top, remove the valve cover and check the chain guides. remove the top guide, it's between the cam sprockets covering the chain. see pic.

[mchkc240]

So does it mean like I have to change the chain? Or just adjust it? When do i have to change the chain? Thanks

[s13redtaz]

sounds like it could be your timing chain guide.this might help-its a step by step processhttp://forums.nicoclub.com/zerothread?id=105618