This is a non-honda question but I'm helping a lady with a v6 chevy blazer that has excessive piston slap noise. She said that there was an oil leak before that she didn't notice. She had it fixed but then there was too much oil replaced.

The engine 'seized' and didn't start up at first. Then after the piston slap noise started.

Its too loud to be knocking and its not a metallic noise. The noise speeds up with the engine but is noticeable even with the engine heated up.

Worn piston rings causing piston knock seemed to make sense since a non-lubricated engine would destroy the rings but the car is not burning oil and the noise is more muffled- not a distinct metallic noise.

Vacuum gauge test shows the vacuum at idle at 19 in/hg but occasional floating 1 or 2 in/hg. Revving the engine it will climb a few inches.

Any ideas of anything else it could be? Or can that still be piston slap?
Shes looking at a piston and ring replacement.

 

Beyond my internet understanding ... best luck to you.

generally noise, if it continues to run, isn't a top-drawer issue for me. Just saying.

 

I look at noises as something that will lead to a more expensive issue if not addressed.

 

I'm going with rod knocking due to worn crankshaft bearings from low oil level. Makes the most sense.

Except for the floating vacuum gauge needle.