Im hoping someone can help me with this problem. I have searched and searched but not found anything just like my predicament. I have a newly rebuilt b18a in my integra with the following internals:

-JE Forged Pistons w/ Hastings Rings
-Eagle Rods (w/ ARP bolts)
-ACL Bearings (Main + Rod)

When we started up the engine everything seemed to be running just fine, until the motor got up to temp and the idle dropped then there started a knocking/pinging noise (hard to explain). It really isnt it that loud but is very noticeable. We were scared it was piston/rod knock or a spun bearing, but the twist is that it essentially goes away when the rpm's rise, as where I was told slap or bearings would get louder and last through the whole rpm range. We tried adjusting the valves but that didnt help. The sound seems louder around the intake manifold area. The engine also runs louder in general (I heard something about forged pistons being louder?). My friend and I are just stumped and would really appreciate any input. Thank you for looking and thanks in advance for any help.



Modified by xxxmikenicexxx at 2:29 AM 8/23/2004

 

whats your compression? and how loose where the rings gapped?

 

Compression is right around 8.9:1, and the rings were gapped right in the middle of the specs, not on the low or high side. This car will also obviously be seeing boost so Id like to get this figured out before I kill the motor. But if it were a bearing or slap wouldnt it definitely not go away when the revs are higher, it would get louder correct?

 

And also what exactly does piston slap sound like? Anyone have any wav files of it? And wav files of a motor with forged pistons? Regardless my motor def doesnt sound right to me.

 

Anyone? Ill TRY and get a sound file up soon also.

 

piston slap usually can be heard when the engine is cold, and its not that loud. damn i cant really describe it but it sounds like valves but its a slapping noise. bearing knock sounds mettallic and will get louder when you rev up the engine. If it sounds like a chain slapping the exhaust, that is usually detonation. check your timing and how old is the fuel in your system. check your fuel pressure too to make sure your getting enough.

 

who miked the pistons and what was it honed too. 5 thousands over is what i usually do.

 

Well, couldnt get a wav file yet, but I checked it and it almost definitely seems to be coming from the bottom end...you can really only hear it after the engine is up to temp and at idle. The car also sounds like a diesel and runs loud (I heard this is what forged pistons sound like though). It sounds more like clicking, like I said kinda like REALLY loud injectors (def not the injectors though) and kinda metallic. Anyone have any input? Lastly, does anyone happen to have sound files of piston slap, rod knock, spun bearings, detonation etc? Would really help in pinpointing noise. Please send to xxxmikenicexxx@hotmail.com or post up, it would be much appreciated, as is any help!

9sech22civic - not sure but I will try and find out what it was honed to.

 

Try pulling 1 plug wire at a time, listen to the noise, if it dissapears it might be a rod knock in that cylinder. Did you adjust the valves?

 

edit. you already tried the valve adjusting. any leaking around the exhaust manifold?

 

Yes it is smoking around the exhaust manifold, but the guy who built it with me said it is normal and just burning off gunk? What would that have to do with anything out of curiousity? Also, this motor also has 0 miles on it and only been run a total of maybe 15 min, so the rings arent really seated so wouldnt pulling off the spark plug wire flood the cylinder with gas and wash out the rings?

 

Just went out and listened to it again, I would have to say the noise is very loud and even louder under the engine, so almost def a bottom end problem? I was thinking detonation because we had problems with timing but I guess it is way too loud for that?

 

be temp. eliminating the explosion, you can hear if the bearing noise dissappered.

 

? and another ? with all the stuff I just asked...sorry Im confused.

 

you would here clicking noise if you had a leak around the exhaust side

 

its kinda hard to diagnose it for ya, since i cant actually hear it. good luck tell me what your outcome is?

 

I definitely will, and thanks so much for the help.

 

I talked ot my friend....he belives the ptwc was around .0015", is that ok for my setup?

 

kinda tight for JE pistons.Pistons could have rubbed on the cylinder walls and now they could be scuffed.That will make a tapping noise.

 

Well its between .0015-.002, so i guess my question is if it was too tight it would make that noise constantly correct? And if they are too small will it be a big problem especially with boost? Would this create vibrations in the car? I hope its not a huge problem because I would hate to have to tear the motor apart again.

 

rod knock

 

Hmmm...rod knock? I doubt it is just because i was told it would get louder when the rpms increase?

 

Especially with boost,you should have more clearance.Im willin to bet its piston slap.Might as well take it apart now before more damage occurs.

 

Yeah but if its piston slap that means theres too MUCH ptwc and the boost should expand them and maybe take care of that correct?

 

I had a sound similar to what you are explaining in my D15 w/ 200k miles. I had a motor almost built for a swap so i just drove it. The sound was loud at idle, got a little louder right when I pressed on the accelerator and then went away. I drove it that way for about 2 weeks...then the motor froze. When i tore it down bearing on #1 spun 180 degrees.

Not to scare you, but I would have someone else who knows listen, or tear it down and check all of your tolerances. IMO if your rings are gapped in the middle of the factory range they are too tight for a turbo car. I believe the rings in my B16 are gapped to .019, but I would have to look back at my notes to be sure...all the information just runs together in my head.