Well I was driving one night and I noticed smoke coming from the rear ( 5th gear 55 mph and gassing it). So I pulled off the road and when it came to an idle I could hear knocking.
Upon further inspection the knock was only at an idle. The noise would go away at @ 1500 RPM.
Then I let the car sit for a month and when I started it it didnt knock at all untill it it came down from fast idle.
The knocking noise seamed to come from the bottom.
Well I dropped (yes out the bottom with ramps, tall stands and my motor hoist) the motor yesterday. Pulled the heads off and found nothing. Checked the pushrods(roll test). checked the valves and springs(hammer handle test). Rolled it over and pulled all the rod and main caps off (except for the rear main, can't get the rear cover off while on the stand) and found nothing.
I changed the oil @ 300 mi before this with mobil 1 and a fram. when I drained the oil I expected to find metal on the drain plug, but when i panned my oil there was alot of brass metalflake at the bottom. I was certain it was bearing material.
I did do a mechanical over reav once but put a few hundred on it sence that.
Where do you think the brass came from?
The piston bore looks really smooth for a 40,000 mi car, I bought last july and put mabee 2000 mi on it.
Can the piston slap get that bad. But then where did the brass come from?

Id like to figure out my problem befor I drop it off at the machine shop this weekend.

Any help is appreciated. I have built and repaired many gen 1 motors in the past. This is a new breed to me!

 

Sounds like piston slap. With the car sitting a month, that may have something to do with it. Mine does the same when it sits for a long time. I am told this is normal.

 

What about the brass in the oil? This was not the normal piston slap. I once had a car with a ZZ3 in it I know what piston slap sounds like. When i fired it up with a buddie arround they would kringe and give me that hirrified look.
Can the slap get that bad needing new pistons?

 

any one,...any one

 

It might be a rod knock. Try to find out which cylinder by removing a plug wire at a time with the motor running. when you remove one and the noise gets softer or goes away this is your cylinder with the problem.

 

Um, he said he pulled the rod bearings.

I can't imagine where the brass came from - did you check the rod bearings carefully? Arent the bearings copper and lead based - not brass?

 

The rod and mains were mint. Hardly a scuff. Im thinking mabee the piston pin. Do the pistons have bushings in them?

 

Buler.....Buler......

 

No one has any input on this?