Mentat Ghola

HEres the situation, b18c engine, rebuilt 1000 miles ago. Everything is new.
Just yesterday i noticed a weird knocking noise.
When i first start the car cold, it sounds normal for 1-2 minutes, then theres like a 2 minute period as it warms up where theres like a tapping noise, then as the engine reaches operating temperature the noise fades and completely disappears.
Its really stressing me out, car runs perfectly. Im not sure if its a lubricatrion issue, or ignition knock, or mechanical. I just switched to synthetic oil after the 1000 mile break in period. I dont know if thats at all related, Im not sure if this noise was there before this oil change, mayb e it was i just never payed attention.
Some more relevant info, the timing belt also needed to be retensioned, it was a little on the loose side.

what should I do? retorque head bolts? change oil/filter?

Builda'Teg_92

Did you use aftermarket pistons?

Mentat Ghola

Nippon gsr pistons, .25 oversized. I dont think its piston slap, the pistons were a tight fit in the cylinders.

Markyboy

If there not coated pistons if seen it,before slap when its child then they are fine once warmed up but if its not that then id be a lil woeried and checking the oil for shavings and being 100% that its not something that will cost me alot if its something I could prevent. Just what I would do

v8killaz

what the **** are you saying dude. speak english

Dioxine

There is a huge difference between a knocking and a tapping. Is it it like a rod knocking sound or like a valve lash tapping sound. Cause 90% of the hondas i built had valve lash tapping when started cold then when warmed up it went away. But that usually happens immedeitly after start up

Mentat Ghola

Its not very loud, if youre inside the car, you could barely hear it. youd have to know what youre listening for, and it only seems to tap at idle, if i rev it up to 1500 sound disappears.
could this be a bad head gasket? i was idling for a while at a drive thru atm and the motor got a little hot. more clues.

Dioxine

Detonation? Im pretty sure headgaskets dont make a noise when they go out.

10psiLsEf2

Cold start knock.

What oil weight are you running?

and did the noise start after the oil change?

Mentat Ghola

Seems like changing the PCV valve has stopped the tapping. The old one was faulty, it was letting air go both ways. This time i spent 20 bux at the dealer instead of 4 bux at pep boys.

10psiLsEf2

could make sense. maybe it was a ping.