high end rattle

[Stephen.Morton]

I have just purchased a 240sx se, 93, that has a top end rattle. sounds like a loose rocker in an old chevy v8's.I understand that this engine has DOHC's and that the rockers run right of the cam shaft.Just getting into imports, have built v8 chevies for 15 years.Can I do the same vale lash adjustment ? Also, the noise is in the front of the block, can feel it in the valve cover.Could the chain be loose? Car runs fine but has small bog at 3000 RPM.Can someone let me know pls.

[Hijacker]

more than likely it's the timing chain slapping the upper guide. possible problems to cause that are a bad tensioner or a stretching chain.

I've heard some stock 240 motors run with some valve clacking before, but it was due to an improperly shimmed head after a rebuild. A normal motor that hasn't been touched usually doesn't clack in the valve train since it's a cam on bucket style.

[se-rious]

i have that rattling noise on my 95 240. at first i thought something was wrong with the valvetrain but then i realized it was a chain tensioner causing the belt to make contact with the valve cover. if you put your finger on the front of the valve cover, you will be able to feel the chain touch the valve cover. does anyone know how long can i drive my car like this?

[InsanityInc]

I have just purchased a 240sx se, 93, that has a top end rattle. sounds like a loose rocker in an old chevy v8's.I understand that this engine has DOHC's and that the rockers run right of the cam shaft.Just getting into imports, have built v8 chevies for 15 years.Can I do the same vale lash adjustment ? Also, the noise is in the front of the block, can feel it in the valve cover.Could the chain be loose? Car runs fine but has small bog at 3000 RPM.Can someone let me know pls.

Are you sure it's from the engine? The cars have lots of interior rattles. Also, it can't be a rocker, as the KA24DE doesn't have rockers. It's a direct mechanical valvetrain (the lobes sit on "buckets" which sit on the valve stems, so the lobes directly actuate the valves). Any valvetrain noise will almost always be coming from the timing chain and various guides it has. If you haven't already, take off the valve cover and see if your top guide is still there, and attached. It's a little black piece of metal that sits on top of the upper timing chain. If it's broken, just take it out and chuck it.

[Hijacker]

Are you sure it's from the engine? The cars have lots of interior rattles. Also, it can't be a rocker, as the KA24DE doesn't have rockers. It's a direct mechanical valvetrain (the lobes sit on "buckets" which sit on the valve stems, so the lobes directly actuate the valves). Any valvetrain noise will almost always be coming from the timing chain and various guides it has. If you haven't already, take off the valve cover and see if your top guide is still there, and attached. It's a little black piece of metal that sits on top of the upper timing chain. If it's broken, just take it out and chuck it.

he asked if there's a valve lash adjustment he can make. Valve lash has to do with contact the valve receives from the cam. Rocker or no rocker, there is still valve lash. A misproperly shimmed head, even on a cam on bucket design, will clack from improper lash.

Also, he said it was definitely coming from the front of the motor, which tells me he was standing in front of it listening to the motor and not confusing it with an interior rattle.