Strange knocking in engine?

[Tosh]

How is it almost but not quite like piston slap?
Why so secretive about the specifics on the car?

 

[HACCOFFICER]

oh, sorry, its a 1999 Olds with the 3100 V6.

This engine has bad piston slap at startup. This noise thought sounds different than the usual slap.

 

[Mike_dup1]

First of all, the oil should be 5w30. Does it not say that right on the filler cap. What you are running is not what the engine was designed to use. I know you think its helping piston slap but its not really.

Have you looked at the drive belt recently and the idler pulley? If it will make the noise when idling spray some WD40 on the belt, not a lot. If the belt is slapping the pulleys it will quite in a second.

 

[HACCOFFICER]

10w30 is also listed in the manual. By adding 20w50 to the 10w30 it made it slightly thicker and I have noticed the piston slap is conciderably quieter.

 

[55Test]

quote:

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1999 Olds with the 3100 V6

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Have those intake manifold gaskets checked.

 

[HACCOFFICER]

Intake manifold gaskets were replaced as preventive maintenance in december, used the fel-pro perma dry gaskets.

 

[Tosh]

>This engine has bad piston slap at startup. This noise thought sounds different than the usual slap.

Oil that's too thick in an engine that already has piston slap at start-up combined with Northern winter morning temperatures? Brrrr.

 

[HACCOFFICER]

I have a knock that comes and goee. I was thier for a day a couple weeks ago and dissapeared and then came back yesterday and is not gone again. It sounds like a rod knock, but knocks slower than the engine is moving. Its not in sync with anything. It does speed up with the engine when you give it some gas. Yet still not in sync with anything. And as mysteriously as it came it dissapeared. Its almost like the piston slap but not quite. I am truly lost. Anyone have any ideas?

Additional Info
engine has 53K miles
good oil pressure
use 89 octane
Oil clean, use 1.5 qt 20w50, 3 qts 10w30 ( helps with the piston slap) Mysterious sound was there once before using this combo.

 

[GoldenRod]

Motor mount ?