Is it possible for piston slap to occur randomly even when up to operating temperatures?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by garyc17 &raquo;</TD></TR><TR><TD CLASS="quote">Is it possible for piston slap to occur randomly even when up to operating temperatures?</TD></TR></TABLE>

slap what? your face?

 

ROFLCAKES

 

If you have piston slap when the car warms up then you will have piston slap when the car is not warmed period.

 

what did the piston say to the face? lol

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by citrus3000psi &raquo;</TD></TR><TR><TD CLASS="quote">If you have piston slap when the car warms up then you will have piston slap when the car is not warmed period.</TD></TR></TABLE>

true.... if you have forged pistons....

this should not occur w/ cast pistons....

do you have forged or cast pistons?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RTW DC2R &raquo;</TD></TR><TR><TD CLASS="quote">what did the piston say to the face? lol</TD></TR></TABLE>
I'm stumped, what?

 

usually only when not on throttle. most dont slap when on throttle

 

 

lmao migs that was funny

 

was the head resurface before and how much.

 

The head was resurfaced and compression was increased to 12.4CR. I run on 98RON. Initially I figured it might be knocking, but the knocking sound continues even when I am off the gas. I also adjusted my tappets to see if that was the problem. If it was a spun bearing, the noise should be there even at idle? It has a very similar sound to that of a faulty CV joint except that is comes from the engine head. Would a worn timing belt cause this?

Actually this started about a week after I changed out my oil from Motul 10w40 to Mobil1 5w40. Could it be the oil?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by garyc17 &raquo;</TD></TR><TR><TD CLASS="quote">Actually this started about a week after I changed out my oil from Motul 10w40 to Mobil1 5w40. Could it be the oil?</TD></TR></TABLE>

Change it back and then you tell us.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JjuuN R &raquo;</TD></TR><TR><TD CLASS="quote">ROFLCAKES</TD></TR></TABLE>


x2

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by garyc17 &raquo;</TD></TR><TR><TD CLASS="quote">Is it possible for piston slap to occur randomly even when up to operating temperatures?</TD></TR></TABLE>

That would be unusual; piston slap usually occurs on engines with forged pistons when the engine is cold. Piston slap may be an indicator that you need new rings. Do a compression and leak-down test. Is the car using excessive oil? Possible oil glazed cylinder? If you had a bad bearing, the motor would have already failed.

Edit: You should try the All-Motor forum for a question like this.





Modified by Tomcat at 8:33 AM 5/30/2007

 

There is no excessive oil burning except for the big black cloud at VTEC and high rpm. Could be caused by too rich a tune. I am afraid this sound may be an indication of something about to go bang. If my plugs are due, will such a problem occur?

Will change out my oil after another 3000miles.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by garyc17 &raquo;</TD></TR><TR><TD CLASS="quote">There is no excessive oil burning except for the big black cloud at VTEC and high rpm. Could be caused by too rich a tune. I am afraid this sound may be an indication of something about to go bang. If my plugs are due, will such a problem occur?

Will change out my oil after another 3000miles.</TD></TR></TABLE>

Running very rich? Did you re-tune the car recently? If you very recently tuned too rich, you may have fuel-washed a cylinder or two (back to ring replacement). Just to reiterate, you should take your car to a competent mechanic and have them check the condition of the spark plugs and do the comp/leak-down test.

 

My plugs look fine except for a black layer of carbon around the edge of the thread end. The tip looks fine with a slight brownish tint. This is the same for all cylinders. None of them look wet. Have yet to do a leak down as the mech I frequent has not fixed the leak down tester yet.

 

Okay, I just got another feedback from a fellow forumer. He mentioned that it could be the VTEC loss motion assembly. The pin that locks the rockers might have become worn down and vibrating in the rocker. Is this possible?

 

Take it to a mechanic. "A knocking noise on and off the throttle" could be a number of things. You clearly don't know what you're doing really (not an insult, just a fact), so take it to someone who does.

 

Piston slap will only occur on forged units, mainly because they are undersized due to their expansion rate, when cold, their piston-wall clearances are in the .005-.003 range.

Worst case scenario, you are experiencing rod knock.

 

I have decided to change out the oil to something much thicker when it is due. The noise is clearly from the valve train.

 

Sounds like it would be the LMA's(lost motion assembly)...these are hydraulic lifters essentially, that keep tension on the vtec rocker while not in vtec. If these go bad, you will hear loud ticking. Use a stethescope and help narrow the noise. If it's a rod bearing, disconnect the plug wire from the plug and see if noise goes away. With no load on the road bearing, noise will go away.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 92TypeR &raquo;</TD></TR><TR><TD CLASS="quote">Piston slap will only occur on forged units, mainly because they are undersized due to their expansion rate, when cold, their piston-wall clearances are in the .005-.003 range.

Worst case scenario, you are experiencing rod knock.</TD></TR></TABLE>

Do you have forged pistons; and do you experience piston slap before your 2.0L gets to operating temp?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tomcat &raquo;</TD></TR><TR><TD CLASS="quote">

Do you have forged pistons; and do you experience piston slap before your 2.0L gets to operating temp? </TD></TR></TABLE>

I am running CP forgings, which have a high nickel content compared to a few others, lower thermal expansion, less piston slap. I don't notice it.

If your bore isn't perfect or you are using a different forging (like a JE) you may notice piston slap.

My piston/wall clearance was .0025, which is on the low side for forged pistons.