Loud ticking/knocking in engine

[nitsudstems]

Before I went back outside this morning I figure it wouldn't hurt to post and get input from others.

When my engine is running there is a ticking/knocking sound in my engine. It's fairly loud and increases with RPMs. The sound seems to taper off in higher RPMs, but it's still their and fairly loud.

A mechanic/friend advised that is was lifters or rods based on my description over the phone. So, I did the dance and got the cam off and the lifters out, they appear fine. I put the cam back on and the timing sprocket so I could turn the thing, no noise.

I got the oil pan off, and shone a flash light up and I can't see anything wrong with the pistons/rods.

The next thing I was going to do is reattach the timing belt so I can turn the engine over while looking up at the pistons to see if anything fishy shows up.

Does anyone with more experience have any further ideas on finding what's going on? I'm nearly to the point of putting it all back together and running the thing until catastrophic failure. Then maybe I can get some cash for its scrap.

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Turned the crank while checking the rods and pistons didn't reveal anything. Upon thinking I realized that the sound didn't occur while turning over/starting, only after the engine was running. Would this indicate a knocking piston? Or is there anything else this would indicate?

[99Metro]

Some ticking is ok. If you have the oil pan still off, reach up there and see if there is any play in the connecting rods/bearing caps of the pistons at the crankshaft. Shouldn't be any noticeable play. I hope your old oil looked clean when you were draining it - very black and/or metal particles is a bad thing. You should check your oil pressure with a mechanical gage >10 at idle with warm oil, 40 psi or so cold and while running at RPM. Even though it may not be low enough to get the low oil light, it still may be too low. You could have a valve problem, but if your compression check on each cylinder is good, you could eliminate that.

Can't think of too much at the moment.

[SchlockRod]

Did you look in the bottom of the oil pan for pieces of metal? I thought my knocking was a lifter, but when I removed the oil pan I found pieces of piston skirt. If that's your problem, it's time for an engine or a new car.
What is the frequency of the knocking? Crankshaft speed (equal to rpm) or half crankshaft speed? Half crankshaft speed could be a lifter/cam problem, cracked piston (my knock was half crank speed), or rod. Crank speed could be something less serious.

[BlazerLT]

One thing we should all be asking is:

1.) What grade of oil are you using?
2.) What filter are you using?
3.) Have you performed an engine flush ever?

The flush cured my ticking. Grab a bottle before you next oil change. Pu the car up on the ramp, pour in the flush and IDLE it for 30 minutes. Do not put it in and drive or even drive up on the blocks.

This stuff will turn even clean oil black as tar as it removes all the sludge blocking your lifters and your lubrication passageways.

[Scrapper]

did you look at the inside of harmontic balancer??
but if it is HMB the knock should be pretty loud..just a thought....

GOOD LUCK THERE BUDDY.....

[nitsudstems]

Thanks for the input everyone. Yes the oil was pitch-black and there were metal shards in the pan when I started wiping the oil out. Back on that day I found a rod bearing with small deformities and the little shunt flattened out and spinning with the crank.

I replaced the bearings and put it back together, and the loud noise was gone. There was a fainter noise that didn’t sound right though. I went to Napa to pick up a stethoscope, brought it back and started the car. As the car was running a noise got louder. I have little doubt now that it’s a piston knock. I’d say it’s time for a new car.

Thanks again everyone.