yes, that's what i consider it now since it makes such a loud noise. my question for all you techs is how do i determine whether the noise is from a Spun Bearing, Piston Slap, Wrist Pin, or anything else?!!? this diesel like noise never goes away and is only heard from 1k to 3k rpm under load. the motor is a rebuilt motor with SRP pistons, total seal rings, ACL bearings, Eagle rods, and ARP bolts all around. the noise however does seem to go away if i resume a certain speed and don't accelerate. please help, i'm getting stressed out here.

 

I've got the same diesel-ing sound in my D16... Just rebuilt w/ SRP 9:1 slugs. Quite a bit of piston slap when cold, but a bit less when hot. The floating wristpins probably contributes a little bit to the noise, but as long as it's not a double-knock noise, you're fine!

 

double-knock noise? never heard of that...what is it? are you saying something like piston slap along with valve lash? or something like that? damn, i'm gonna change heads this weekend to see if that helps. it gets really annoying cause it sounds like one of those really old, high mileage cars!

 

Double-knocking is heard when a wristpin lock works itself loose, thus causing the wristpin to knock against the cylinder wall itself.

The rattling noise you hear is just piston slap. Chances are, you're just gonna smack yourself when you change heads and hear the same noises! I'd sooner check valve lash than swap heads. Does the rattling/diesel noise go away or get less noticable when the motor has reached normal operating temperature?

 

not really. well, after i get off driving on the highway for a few good miles at 70+ mph, the noise isn't as loud but is still noticable from inside and outside the car. i know it can't be a bearing because i just changed all the rod bearings with ACL bearings. i'm not sure if it is piston slap though due to all the things that i've heard. such as the noise going away after the engine warms up. my noise never goes away. so i'm thinking it could be something with the valve train or head. also, it's louder on the intake side than it is on the exhaust side.

one more thing, how can you tell the difference these noises: valve knock, bent valve, piston slap, spun rod bearing...and other noises. thanks for all your help so far PyroVTEC.

 

ttt

 

Diesel sound: Its a header exhaust leak.
Also sounds like a harley with ticking valves.
The source seals itself due to heat expansion,
thats why it is not as loud as it is in the beginning.

Just a guess, because I had the same sound

 

You can use tubing like a stethescope. cut one 90 degree edge, and hold it to the engine at defferent places. keep the other end held to your ear. Use an earplug in the other ear. This has been used by shade tree mechanics for years, (my grandfather showed me this on his El-Camino.)

I've used 3/8" tubing before, but I don't think that's large enough in diameter. You may want to try a couple sizes to find what you hear best with.

Good Day.

 

*Piston slap sounds kinda like dominoes falling and lessens upon warm up, but doesn't go away and sounds like a deisel while driving under low rpm.
*Out of tune valves sounds like a light tapping whle the motor is idling, followed by deteriorated higher rpm performance
*Bent valves sound like some LOUD *** tapping under all rpm ranges
*Spun bearing sounds like someone threw a wrench in your oil pan.

A combo of piston slap and valves in need of an adjustment can make the car sound like ***... adjust your valves before you go pulling the head !

X2

 

quote:
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You can use tubing like a stethescope. cut one 90 degree edge, and hold it to the engine at defferent places. keep the other end held to your ear. Use an earplug in the other ear. This has been used by shade tree mechanics for years, (my grandfather showed me this on his El-Camino.)
I've used 3/8" tubing before, but I don't think that's large enough in diameter. You may want to try a couple sizes to find what you hear best with.


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[Modified by builthatch, 9:26 AM 9/10/2002]

 

or use a long screwdriver, broomstick, breaker bar ,etc