I have an ls/vtec with ctr pistons and when i just start it and the engine is cold it has a knock but then goes away after i drive it and it warms up. it runs and idles perfect. im thinking maybe piston slap but idk anything else it could be? if it is piston slap wat should i do about it

 

It really shouldnt be piston slap with OEM pistons. Usually that happens on cold start with low silicon pistons because they haven't expanded yet. However, that is not the case w/ your high silicon OEM pistons. With that said, that does not hold true for the cheap crap aftermarket OEM rip off wannabe pistons. Either that or your piston to wall clearance is too high due to a honing or something like that. Usually you wont "hear" knock from denotation, especially at idle.

 

yea honestly i dont think the pistons are oem, i have oem b20z pistons laying around i was thinking about having those put in. if piston slap is the issue should i be in a rush to change them is it ganna tear up my walls?

 

Check your oil level.

 

The oil is good.

 

It can, but it will be ok as long as you let it slowly warm up all the way. Basically when my prelude was doing the piston slap sound, I let it warm up for a minute or two before even driving it and would baby it until it the piston slap sound had gone away for 5 minutes or so.

 

those pistons wont slap because i have them but not OEM if they are forged they will sound until they warm and expand but what even makes you think that its just your pistons?look for other sources..

 

Well iv dropped the oil pan and checked every bearing none moved side to side or anything and there was no metal anywhere and it goes away 100% after a min or so, so I was kinda confident it wasn't the bearings. Any other ideas? I take it to 8500 and it takes it no problem no noises

 

I say its normal. when the motor cools all the oil drains down to the oil pan. Once its fired up and everything gets lubed again then its fine. Thats why it makes that knocking noise because it hasnt been lubed will yet from a cold start and goes away once enough oil has passed through

 

Take your valve cover off one day and turn the motor over.....doesnt take but half a second to get the engine lubed.

 

My stock ls does the same thing...it's not a knock but the motor is pretty noisy for about 5 seconds after I start the car

 

Exactly, it is a common issue.

 

ok thanks guys im not so worried now

 

Don't get too comfortable...my motor is a 1993 b18a1 so I expect to make some noise. It's something that comes w/ an older motor that's been beat on.

 

well its ganna go threw a rebuild soon iv had the same setup for about 2 years now so its ganna be 84mm soon

 

2 years of beat down is about the same as 5 years of normal driving

 

It's not my daily tho so 2 years for this car is only about 5000 miles if that.