Ok, I am confused, which is easy these days.
 

Ok, I have an engine knock, from a suspected water pump, replaced water pump, same knock. Take the belts off, no knock .Belts back on knock. I used a copper pipe, I don't hear any knock anywhere unless I am just standing there. Not on the heads, water pump, alternator, power steering pump, oil pan, no where. Noise goes away on higher rpm, engine runs fine, drives fine. Could it be a cheap, bad, new water pump? Neither leaked. Pontiac 1970 engine. Only the new pump had a small amount of play in pump shaft. Thanks regardless. mike

The crank pulley could be failing.

Fan clutch? Loose fan blade?

Check what the other guys said, but there should be no noticeable play in the water pump shaft.

Make sure all plug wires on & good , had a odd knock that would come & go on a friends 400 bird & end up being plug-wire not fully seated on plug.

time to get out the drill. I use an old alternator pulley mounted on a bolt in my cordless drill....then throw a belt around the suspected BAD component (ie waterpump...alt..) and spin it.....individually. :)

Check crank damper and the pulleys there.
Might be cracked. With no belt/load it may not make noise.


:confused:

I had a similar problem about thirty years ago. My friends father came out to help, he was a mechanic. He took his kids squirt gun and sprayed a little water at the belts on the water pump pulley and the knock would go away momentarily, telling us the noise had to do with the belts or pulleys. Unfortunately, I don't remember for sure what I replaced to fix it but I think it was the belts.

If it's truly a "knock" and not a click, tick or tap :) I would immediately think of the crank pulley/damper.

I had the same thing. Chased it for weeks, replaced wp, removed belts one at a time, etc...What was really confusing was that either belt removed reduced it but didn't get rid of it. Both belts off quieted it. I noticed that it was much louder when I listened beneath the front end. That's when I reached up and found one of my crank pulley bolts missing. Reached for the next one and I could spin it with my fingers. The other two were tight. I mean it sounded like a serious knock but it was just the two loose bolts that did it. I actually have a clip of the engine running. I'd post it but couldn't figure out how.
Replaced the missing one and tightened the others and that was it.

Oh yeah, the other thing from your description that reminds me of the problem I had... you just can't locate where its' coming from. Like it's just 'projected' into space. It's hard to press a screwdriver to your ear and the crank pulley when the engine is running.. ;)

I had the same issue once. had one bolt sheared off and another was loose.

Bad mechanical fuel pump?

LOL, I use a 16 inch copper pipe, I wonder if one day my wife will come out and I will do a Dead Pool imitation with a pipe though my skull from hitting the fan.

I will get onto something else for a few days then jump back on it. Thanks for all the tips. mike

Reminds of a story a friend used to tell of when he was just starting as an Olds mechanic. Had a knock he couldn't locate. Belts on bad noise - but belts off OK . The service manager agreed they had to pull the engine and tear into it.

Pull engine and while up in the air on the hoist he notices a rock wedged into one of the pulleys. OH S**t. Pop out the rock and put the engine back. No more noise.

LOL. I will look for rocks. I noticed the knock does not follow the rpm's. It just gets a little louder. It comes and goes. I looked all over to see if it was hitting something, the engine. Its more of a quest now, soon. I will throw parts at it. lol Or, when I get it on the road, the radio does wonders till something breaks, problem solved.

Connecting rod hitting a dented oil pan? Check the pan to see if laying on the crossmember

I checked the pan, and everything external, everything clear. As far as I can tell.

Well, I quit , checked every idea, I am going to have the shop change out the harmonic balancer when I get it inspected. It is now intermittent. So I am backtracking to see what I did. The noise was totally gone this morning, and yesterday. A little noisy this afternoon. I will try and get the water pump to spin on its own, I am wondering about the diverter inside the pump, I used the old one. But the old water pump didn't have any marks on the blades. I have no noise using the stethoscope technique, and with a noise that loud it should be easy to hear. Only hear it when standing there cussing. Sure sounds like a shot water pump bearing. Thanks for all the tips, when I or someone else finds out what it is I will post it. Thanks again. mike