Help me identify this sound, its not timing chain rattle, but its a rattle of sorts

[lbrowne]

89 240sx, the timing chain kit was done not 5k ago....and works like a charm.

I had the valve cover off the other day to check how everything was doing under there and its fine...everything in place.

Yet this car has a rattle. You hear it under acceleration that resembles a timing rattle *somewhat* except louder.

You hear it as well if you're cruising and just lightly press the throttle.

It makes the sound if you're stopped, in the driveway, car not in gear but in neutral, and you press the throttle till you hit about 2500 rpm or so.

Any ideas? Theres no miss in driving, no backfiring....timing chain and guides are all intact...

thanks in advance.

lbrowne

[lbrowne]

update:

with the car idling out there I popped the hood and revved her via the cable.

The sound starts around 2k as I mentioned above, and it really sounds like its coming from the top of the motor. Almost like something is loose but I don't think thats the problem...

Please help asap, this car is going on a long haul soon and I need to know if the motor is still good to go.

thanks again,

lbrowne

EDIT: I wish this link wasn't so old because it sounds similar! And the vids are long gone!

Rattle thread

[navysnail]

hydraulic lifters may be worn, i did a thing on how to test them a little while back, let me find it

[lbrowne]

I took the car for another lengthy drive tonight to do some more testing.

The sound is not there at idle. I have no oil light that comes on, we changed the oil today but she was already making the sound.

It seems that it only starts to make the sound if you cruising in one gear and just lightly holding the throttle to maintain speed. underload and accelerating/decelerating she does not make the sound save for the 2k-3k range....

if that helps

[s13EastTN]

Mine did almost exactly the same thing. Except if yours definately makes the sound in the 2k-3k range, then it's different because mine was also throttle dependant in that area as well. Ok, first impressions where that it was a bad lifter (hoping for the best really) but then it came down to spun bearing, or the chain slacking and hitting something. The shop that is currently fixing my car beleives that there is a large amount of slack in the chain, since my tensioners are gone, and it is causing the chain to do strange things under certain loads. Mine starts at about 2k, and doesn't get louder really as the rpms build, just quicker (a lot quicker than any valve since they open a close a lot faster than this sound happens). Open your hood, have your friend start your car and see if it makes the knock when it first turns on. That would be a sign of a bad tensioner. If the sounds are the same, I would assume that our problems are related and it is your tensioners that are the problem. Hope I helped.

[tonynalli]

the oil light is about a worthless as the gum on the bottom of your shoe. it goes on at about 5 psi. if your engine is running like that for more than a little while. you might as well open your wallet take out any money that you have save it up for a while and buy a new engine.

[frapjap]

My car makes a small clanking sound too. Cept it starts only when you're in the low end of 3rd or 5th crusing at a slower speed (under 40) I think I dropped a sparkplug in teh heat shield last time I changed them cuz it never fell out, but if not, I'd like to be informed on what you did find in case my predictions on mine aren't right.

[lbrowne]

the car doesn't make the sound when you first start it. It seems it only makes it when I'm driving giving partial throttle to maintain speed.

All my tensioners and guides etc are in place.

[spitz7985]

Try posting in the Nissan Online Mechanic section.

[lbrowne]

just started her with the valve cover off and oil gets up top in a hurry. i had to shut her off after a few seconds to avoid a mess.

where are ya 240kid with that write up you said you had?