Maybe piston slap?

[Tommy Boy]

Hello, I'm new to the forum.
I have a 1997 Lumina with a 3100 with over 111,000 miles on it. I recently started getting a clicking noise in the engine which sounds like piston slap. But the funny thing is, it comes and goes and is sometimes quiet and sometimes louder. On accasion when it does this, it will hesitate and will be low on power, like it's down a cylinder. Some days it doesn't do it at all, like I'll drive it around all day and won't hear a peep out of it. Then the next day the clicking will be there. Seems to be doing this on a one day on, one day off schedule. The only thing I've done as of yet to try and remedy the situation was I added some Rislone engine treatment to see if that would quiet it down, hasn't worked yet.

The car normally runs perfect and idles so smooth that you can barely tell it's running.

Could this be a lifter or valve making the noise? I always get the normal valvetrain clatter at startup, which goes away after a minute or two.

Any insight into this problem would be greatly appreciated.

[SappySE107]

Have you ever replaced your lower intake gaskets?

Piston slap is usually during start up and stops when the pistons heat up and expand. If its not doing that, then its possibly a lifter bleeding down.

[Tommy Boy]

Mine seems like the opposite, it doesn't usually happen right at start up. Seems like it happens at any time.

A lifter bleeding down? Can you explain this a little more and what might be able to be done about it?

[SappySE107]

Replace the lifter is about the only thing that can be done about it. However you need to see if that is what it is first. If you can get it to do it while you are in park, you can use a screw driver against your ear to pinpoint the location of the noise. You can also do a compression test but that may or may not catch it.

[Tommy Boy]

Yeah, I'll try that stuff.
Like when I was driving to work this morning (20 min drive) it did it about 2 mins after I pulled out of my driveway and went down the road, then it quit about 10-12 mins into the trip and then came back slightly in a few more mins, then went away completely.
Then I was driving home tonight and not a tick out of it besides the normal valvetrain noise at startup which goes away after a min. The engine never hesitated or felt like it was down a cylinder like it did twice before.


Seems pretty random to me.

[Juglenaut]

The engine could have a lean condition and starts to knock, the ECM may be compensating for it. Try and locate the cylinder, look at the spark plugs, use the driver trick. Could be as simple as the ECM compensation for a lean condition.
Either that a valve, push rod and lifter may be worn enough to cause poor vaporization in one cylinder that cause slight wobble or slap in another. Excessive lash.

[Tommy Boy]

Well, the car is at the mechanics right now, and he's going to have it for a week while I'm gone on vacation so we'll see what he can figure out. Hopefully it's nothing serious but I'll let you guys know when I get it back.

[Superdave]

Mine was doing the same... the sound would come and go. engine ran fine though. 1 pass down the strip and it spun a rod bearing.. lol