Piston Slap?

[Ghostdrifter]

Hey guys, I have a delema. I bought an AMS Adv. rebuild kit w/ Arias pistons(.20 over)for my KA24DE and I had a company assemble the engine. The problem is that when I installed the engine into my car and started it up I heard a ticking noise, so I used a hose to listen in on the engine and I heard a clanking noise. So I took the engine out and brought it back to them to check it. When my dad went by to see what was up,since I had to back to school, he said the piston was loose inside the block. What I want to know is, could the noise I was hearing be piston slap and is it suppose to be like this?

[seven.62]

when i had a built motor with pistons and everything else it always ticked when i stared it up and it was cold but when it warmed up it went away.
i have herd several built motors do the same too, thought it was normal

[LA_phantom_240]

Yeah thats pretty normal for a built motor. Usually because the piston rings are just a tad bit off in their sizing or not being broken in just yet. They need to set to achieve maximum compression and not be noisy anymore.


EDIT: lol. i just noticed we are all from louisiana. crazy eh?

[MOUNTAINGARAGE]

Do you have the spec's on the build? The piston diameter and cylinder wall measurements will tell you alot.

have you detonated the motor at all? even a remote possibility of detonation?

are the skirts on the pistons short or long?

if the noise goes away when the motor reaches operating temp. ....don't worry about it. forged pistons expand at a different rate than cast.


btw LA_P - rattle/slap has little or nothing to do with piston rings. there is no setting a piston ring, there is only filing for ring gap. compression from rings is determined by ring tension. Tension and Gap are not related, unless you have no clue of what you are doing.

[byhi]

Piston slap is caused usually by installing a piston in backwards, see, a piston isnt exactly centered on the rod, it is off by slight thousandths of a mm... designed so that when the piston comes back down from the combustion sequence it wont rock back and come down "crooked" (lehmans terms)

[MOUNTAINGARAGE]

Piston slap is caused usually by installing a piston in backwards, see, a piston isnt exactly centered on the rod, it is off by slight thousandths of a mm... designed so that when the piston comes back down from the combustion sequence it wont rock back and come down "crooked" (lehmans terms)

No, I disagree.

1. the pistons have arrows on them most of the time. so unless it is a major error, usually does not happen with a reliable builder.

2. increased piston to wall clearance causes piston slap in most cases.

3. I have put together alot of engines and most of them had piston slap at startup.

4. High boost and High temperatures cause pistons to increase in diameter. If you do not build to these conditions excessive skirt wear will occur. when you build to these conditions(increased piston:wall clearance), Piston slap is going to happen, period, end of discussion.

thanks, for reading, have a nice day. :wavey:

[bardabe]

So piston slap = caca????

ionos I hear a slapping noise in my motor too whenI first start it up only at idle tho after it warms up its fine. it sounds mean as hell under boost alot of ppl think i got a "V6" when in reality its only an SR... he he he

[Ghostdrifter]

Thanks for your help guys. Just wanted to make sure it was fine, so now all I have to do is get it back and put it BACK in

[shayrgob240]

maybe they bored the engine too much and the piston is slapping as a result.

[MOUNTAINGARAGE]

maybe they bored the engine too much and the piston is slapping as a result.



^^^read above.

[LA_phantom_240]

Good info mount.

[driftenthusiast]

As the other guy said its normal for forged pistons to slap until operating temp because they have a higher clearance becuase they expand more then stock piston do.

[ledzeppelin240]

Pistons are oval shaped, the wrist pin area (piston pin) is a bit smaller than Skirt sides (the major and minor thrust sides) due to there being a higher mass of metal there so all the expansion is done in that area. Most Pistons are also barrel shaped.

MOUNTAINGARAGE knows what's going on, it's awesome to see someone who knows what they are talking about...

[MOUNTAINGARAGE]

Pistons are oval shaped, the wrist pin area (piston pin) is a bit smaller than Skirt sides (the major and minor thrust sides) due to there being a higher mass of metal there so all the expansion is done in that area. Most Pistons are also barrel shaped.

MOUNTAINGARAGE knows what's going on, it's awesome to see someone who knows what they are talking about...

Thanks, it is kinda hard to let people know what you know without sounding cocky. I'm 32 and have had 21 cars, all of which have been modified somehow.

Thanks for the kind words, glad to help. :wavey:

[2_fast_240]

Does this mean if you dont have piston slap at startup with forged pistons its bad