The sound of rod knock?

[aleph1]

My SR20DET (94 finned redtop) makes what I can only describe as a clanking noise at light throttle condition, but it goes away when I step on it more or let it idle. The engine runs great other than this noise. Laid down 220whp at 9psi at a mile above sea level.

I was told by a local shop that one of the rod bearings got stuck and that I needed a rebuild or a new engine. I want a second opinion before I spend that kinda money. I find it hard to believe...If it helps at all, they installed a set of RAS when I had them try to diagnose the noise and when I took the car from them that night, the noise was noticably louder and more metallic sounding, where as before it was more of a droney clunking...

Thanks!

[ILikeMy240sx]

Could you tell us where the noise is coming from?

When my rod and main bearings went out, I actually heard it by the valve cover near #3 cylinder. When I took my moyor apart, my rocker arms were toast and the rod bearings on #3 were toast as well. If the noise starte quite and gets louder and louder as you drive it, I would guess it's the bearings. That's what mine did. It started very quite then it got louder and louder.

[aleph1]

Yeah, it does sound like its coming from the valve cover.

And as a correction- the noise is persistant throughout the rpm band, but the turbo kicks in and its hard to hear it while driving past 4Kish. But if you rev it with the hood open its clearly heard.

Its just weird to me that this noise was fairly quiet, but RIGHT after the rocker arm stopper install it was louder.

So I guess its probably the bearings then eh? I suppose its probably cheaper to just get another longblock...

[ILikeMy240sx]

To see if it's your rod bearings, pull your oil pan off and the baffle plate right above it and check for metal shavings. Bearing materal is bronze in color

[yellow_jacket]

Noises are almost impossible to diagnose over the internet. If you are unsure of what it is, then I would drop the oil pan and check the rod bearings.

I don't know if this will help you or not, but the crank runs at 2 times the speed of the cams. Therefore crank noises tend to be much quicker than lifter noises.

[aleph1]

I'll see if i can get a recording of the noise...

[Hijacker]

if you fix it now, and I mean today you might just get away with just new inserts (bearings). Only problem to do this on this matter you got a pull the engine that upper pan is bolted to the trans-, alternator block and anything else on the bottom of the motor. If you're going to go through all that I would check the main bearings and if you catch it early enough the crank may not need turning, if it does you can get undersized bearings from the aftermarket companies. if it is the bearings and you keep driving the next step is basically the motor will destroy itself usually mangling the crank severely thus making that not even rebuiltable or repairable!!!!!!!!

[aleph1]

A mechanic at my work with experience with DSMs and SR20DE says it might be a lifter...