Have a new engine for a FI application. Engine fresh from machine shop (GSR). Fully sleeved, built head, supertech valve springs, etc....


The issue: Engine idles and runs fine, but when it idles back down from a rev, sometimes you hear a little metallic sounding "pop/clank" kind of noise. It is not rod knock, engine oil is fine.

Sorry I can not be any more specific. But it is pretty consistent. Straight off of a rev, as the engine starts to idle back down to resting, it makes the little metallic pop sound. Almost like what a valve would sound like when being pulled back into the bowl from being stuck open?

Any suggestions?

I am out of town. We will pull the cover off monday/ inspect/leak down test.

I should probably have waited to post this, but while I am out of town, this will help me with more options to look into while I am gone from the car.

 

how loud is it. like just noticable? or realy loud?

 

just noticeable.

 

Is the valve lash adjusted properly ?

 

yes. but I will recheck it monday as well, since it has never ran ever, good chance maybe something occured since it's first startup. All is brand new. Maybe something seated correctly and wasnt before when I did the adj! Thanks man.

 

did you re-use an old set of pistons?

 

It is alll new

 

Most built motors I have heard are generally louder than a stock motor if you used an aftermarket piston.

 

The engine isn't moving is it? I had a similar issue, couldn't figure out what the hell it was, then I found out my engine would move just slightly and the dumptube would bump something under the car that I didn't see when I made it.

 

Did it do it with the clutch pushed in? I had a motor make noises kinda like tht, and it was from the clutch disc springs flopping around hitting the flywheel bolts.

 

i have a car thats doing something similar right now, i think it has to do with the vtec solenoid/ vtec pins in the rocker arms. perhaps even a sticky LMA.

 

Yeah my car does the same damn thing, does it go away for the most part after it warsm up??? Mine does but when its cold its super loud oonly at a certain RPM in the head. This same head didnt make a sound and i put 8 miles on it and had my sandwhich plate break off the LS block so i shut it right down no starvation of oil to the head cause it was barely reving and i built a gsr block with ls forged internals and put the same head on and since day one its makes that metallic popping noise from the head. I have been runnign it liek this for 5000 miles without any problems, i have a head thats beat up but the LMA's and rockers are good that im going to switch out and see if that repairs the problem.

Anyone else have input?

What up dave!

 

You sir sound like a victim of Piston Rattle. I know it sounds like the head but its not. Once everything warms up, the pistons swell and take up enough clearance to quiet the noise.

Ive seen this happen a few times and ive noticed its usually when a used set of pistons are re-used in a build. Im sure it could happen with new pistons, but ive noticed its more common with motors that have re-used pistons.

Thats why i was asking the OP if he re-used a set a pistons. I went through the same **** with a friends freshly rebuilt boosted B18c. I tried 11 different valve lashes one day to come to the conclusion its got nothing to do with the head. I even pulled the pan off, took all the caps off the rods and inspected the bearings, just because it was such an usual noise. That clinking clacking sound was the piston rattling in the cylinder at cold temps. Had another friend with the same problem, he re-used 2 old pistons and bought 2 new ones, the noise wasnt as loud but was still audible till the engine warmed up. I dunno, just something to keep in mind, Good luck.

 

nope its definatly not the pistons, i know what pistons rattle sounds like and a head nlise sounds like. But the OP scould be experiencing that.

Im using the same pistons/rods from the ls block in a gsr block with all the same clearences and it has the same pistons slap noise when cold but the head noise is somethign way different

mine only makes the loud noise between 1300 and 1500 rpm from the head

 

Wade, you have an Autronic, right? Is it controlling vtec by rpm only?

The Honda ecu won't engage vtec when you free rev the motor, but most aftermarket ecus do and you will hear that noise. I'm sure that's what it is, and if it is, don't sweat it.

 

I will look more into it monday. I am in chicago now for the Chicago Auto Show. We are swamped in snow from last night.

Tony1, vtec is engaged by rpm with my autronic. Can you go into a little more detail about what you were saying?

I know it is not my engine moving or anything. All i can think is it could be a sticky LMA or some kinda rocker issue. It does sound like a stuck part that is UNsticking and returning back to its original location though.


Thanks guys, keep em coming@

 

The engine isn't moving is it? I had a similar issue, couldn't figure out what the hell it was, then I found out my engine would move just slightly and the dumptube would bump something under the car that I didn't see when I made it

I HAD A SIMILIAR ISSUE AS THIS AT IDLE I COULDNT HEAR IT, BUT CRUISING DOWN THE ROAD PASSING CARS ID HEAR A METALIC CLICKING GOING ON I WAS LIKE WTF PUSH THE CLUTCH IN AND WALLA WOULD GO AWAY. WELL I HAVE FOUND OUT THIS IS WHAT IT IS LIKE WHEN YOU ARE BREAKING THE GEARS WHERE THE TRANNY SHAFT GOES THROUGH THE CLUTCH PLATES AWAY LOL. WE PULLED MY TRANNY AND THE FIRST PLATE WAS COMPLETELY ROUNDED OFF, AND THE SECOND WAS REALLY CLOSE TO THAT AS WELL.

 

any other ideas?

 

If I had to guess, LMA?

 

yea seems to either be a LMA or rocker/dowel issue. Monday I hope it will get looked into.

I still dont understand what Tony1 was trying to explain to me.

 

think hes trying to say because vtec is engaging your hearing the pin lock and unlock the rockers, with a normal honda ecu it would not engage when you free rev.

 

but i am not revving it high enough for vtec to engage, i am only revving it to like 2500 and letting it come back down.

 

he's saying that with aftermarket ecu's it will turn on the vtec solenoid if you free rev the motor, while not moving. But oem honda ecu's won't engage it, because you need to be going over a certain speed..... so thats the noise he thinks your hearing is the solenoid disengaging after you rev the motor.

 

guess i was too late..... maybe one of the pin's for the lma is not in ?

 

the head was inspected by a machine shop, but I guess things can be over looked. I will get into it monday perhaps