Piston Slap? NO!

0dd3n · Post by **0dd3n** » Tue May 03, 2005 12:11 am

Ok, ive read the posts on engine knock and what not but theyre not helping me out. i know neons are known to have clicking or knocking noises when they are cold or sometimes when they are warmed up, but my noise is starting to bug me, i might just take it somewhere and have them figure out what it is unless you guys can help me. when my car is fully warmed up, i head a really nice and now noticable inside the car, clicking noises which sounds to me like the pistons. i dont know what it is. im really hoping its not a bad piston slap or anything too serious. im looking at 2.0 rering kit, maybe that would help, and possibly the 2.0 bottom end rebuild kit too before i get my other bolt ons here soon. im still new to tuning and stuff, so give me some input on what to do, thanks all

Kernel Panic · Post by **Kernel Panic** » Tue May 03, 2005 10:18 am

The clicking noise could be your injectors. Run the engine, pop the hood, and listen. Check your oil while you are at it.

solodogg · Post by **solodogg** » Tue May 03, 2005 2:13 pm

if you hear it in the car, it's not the injectors

re-ringing the motor won't help it either. piston slap normally occurs on a neon when the bearings are shot. had the oil pressure light ever come on? running low on oil (even by a quart) if either of those..most likely you will need a rebuilt bottom end. good luck, i've been there before...sucks ass

ram50rocket · Post by **ram50rocket** » Tue May 03, 2005 2:48 pm

solodogg wrote: piston slap normally occurs on a neon when the bearings are shot. (

I hope not, my 02 acr has done it since I got it at 27 miles on the odometer. I went with a friend to pick up his brand new 05 sxt and it makes the same noise. Another fella I met with an 04 sxt also has the same problem. I'd also like to add that my 89 ram50 has a dodge 2.0 and it has always made the same noise, including my 86 chrysler conquest with a 2.6 4 banger. I think it's just a chrysler/mitsubishi 4 cylinder 'thing'. I wouldn't worry too much about it as long as you take care of your car. And remember this is a forum, you may get different opinions.

GaryHowell · Post by **GaryHowell** » Tue May 03, 2005 3:16 pm

solodogg wrote:if you hear it in the car, it's not the injectors

re-ringing the motor won't help it either. piston slap normally occurs on a neon when the bearings are shot. had the oil pressure light ever come on? running low on oil (even by a quart) if either of those..most likely you will need a rebuilt bottom end. good luck, i've been there before...sucks ass

When the bearings are shot that is called rod knock, not piston slap. It is a completely different noise than piston slap.

ram50rocket · Post by **ram50rocket** » Tue May 03, 2005 3:19 pm

Thanks Gary, I already knew my balls weren't shot, just trying to keep the peace.

solodogg · Post by **solodogg** » Tue May 03, 2005 3:43 pm

GaryHowell wrote:
solodogg wrote:if you hear it in the car, it's not the injectors

re-ringing the motor won't help it either. piston slap normally occurs on a neon when the bearings are shot. had the oil pressure light ever come on? running low on oil (even by a quart) if either of those..most likely you will need a rebuilt bottom end. good luck, i've been there before...sucks ass
When the bearings are shot that is called rod knock, not piston slap. It is a completely different noise than piston slap.

and you would disagree by saying that spinning the rod bearings and the main bearings would cause piston slap, since the pistons will walk all over the cylinder walls? I hope you wouldn't, since when i spun all of the bearings in my 2.0 the cylinder walls were out of round by 12 thousandths...and when we spun the bearings in the 2.4L motor we built...they were out of round by 8 thousandths. Yes...spun bearings cause rod knock..and also piston slap.

GaryHowell · Post by **GaryHowell** » Tue May 03, 2005 3:43 pm

ram50rocket wrote:Thanks Gary, I already knew my balls weren't shot, just trying to keep the peace.

I was pretty sure you knew. You seem to understand a lot about cars. Some of the NoObs are still learning, thought I would give them the benefit.

solodogg · Post by **solodogg** » Tue May 03, 2005 3:44 pm

and also...if yours does it when it's warmed up...yes that is a bad sign. every neon i've had does it when they're cold..until everything expands, then they're quiet as a whistle. at least all 4 of the neons i've owned...dohc and sohc...have all been this way.

GaryHowell · Post by **GaryHowell** » Tue May 03, 2005 4:01 pm

solodogg wrote:
and you would disagree by saying that spinning the rod bearings and the main bearings would cause piston slap, since the pistons will walk all over the cylinder walls? I hope you wouldn't, since when i spun all of the bearings in my 2.0 the cylinder walls were out of round by 12 thousandths...and when we spun the bearings in the 2.4L motor we built...they were out of round by 8 thousandths. Yes...spun bearings cause rod knock..and also piston slap.

If you spin a rod bearing, it was most likely cause by one of 3 things. Improper torquing of the rod bolts, oil starvation, and or forgien matter in the oil. Spinning all the bearings as you describe would be a complete loss of oil pressure. Mains would go first since they are the first ones to get oil, then the rods.

Piston slap is the pison rocking in the bore, and the skirts hitting the cylinder wall are what makes the noise. This occurs as the piston change direction at the end of the stroke and rocks. The noise is noticable, but not as loud as rod knock.

Now when a rod bearing fails, and you get rod knock. That noise is generated by the extra space created by the rod bearing being ground away. As the piston gets to the end of the bore, and the crank rotates through the now bigger hole in the end of the rod, it slams into the opposite side of the rod, creating the loud noise. Rod knock is louder than (normal) piston slap, and you would never be able to hear the piston slap over the rod knock.

Now at the sametime the piston can now go further up the bore because of the increased space where the rod bearing is supposed to be. The piston contacts the head, and that cocks the piston hard tearing up the cylinder wall. It is not cause be (normal) piston slap, it is cause by someone continuing to run an engine long after the rod knock started. One of the disadvantages to a big system in your car. If you continue to run it like that eventually the rod will fail from the abuse and leave the engine at a high rate of speed.

Louie · Post by **Louie** » Wed May 04, 2005 12:12 am

GaryHowell wrote:
solodogg wrote:
and you would disagree by saying that spinning the rod bearings and the main bearings would cause piston slap, since the pistons will walk all over the cylinder walls? I hope you wouldn't, since when i spun all of the bearings in my 2.0 the cylinder walls were out of round by 12 thousandths...and when we spun the bearings in the 2.4L motor we built...they were out of round by 8 thousandths. Yes...spun bearings cause rod knock..and also piston slap.
If you spin a rod bearing, it was most likely cause by one of 3 things. Improper torquing of the rod bolts, oil starvation, and or forgien matter in the oil. Spinning all the bearings as you describe would be a complete loss of oil pressure. Mains would go first since they are the first ones to get oil, then the rods.

Piston slap is the pison rocking in the bore, and the skirts hitting the cylinder wall are what makes the noise. This occurs as the piston change direction at the end of the stroke and rocks. The noise is noticable, but not as loud as rod knock.

Now when a rod bearing fails, and you get rod knock. That noise is generated by the extra space created by the rod bearing being ground away. As the piston gets to the end of the bore, and the crank rotates through the now bigger hole in the end of the rod, it slams into the opposite side of the rod, creating the loud noise. Rod knock is louder than (normal) piston slap, and you would never be able to hear the piston slap over the rod knock.

Now at the sametime the piston can now go further up the bore because of the increased space where the rod bearing is supposed to be. The piston contacts the head, and that cocks the piston hard tearing up the cylinder wall. It is not cause be (normal) piston slap, it is cause by someone continuing to run an engine long after the rod knock started. One of the disadvantages to a big system in your car. If you continue to run it like that eventually the rod will fail from the abuse and leave the engine at a high rate of speed.

100% correct.

i had a 300zx twin turbo, spun a rod bearing racing. and didnt have the means or will to fix it right away. 3 months later, bent the crank , a rod, and messed a piston up pretty bad.

the piston slap i get in my car everyday (now with over 80,000 miles) is the same piston slap chrysler has a tsb on. if you're covered under warrenty, and have the proper paper work (aka, the tsb) you have a very good chance of getting a whole new shortblock from the dealer to fix the fact that your cylinder 1 and 4 are slightly oval causing your piston skirts to slap the walls.