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Need Some Help With An Engine NoisePlease

stumedic

stumedic

Contributing Member
"OK, my Gen IV 502 has some so

"OK, my Gen IV 502 has some sort of knock. Can't seem to easily localize it, so today I spent a couple of hours in the bilge with a piece of hose. Anyway, the sound is the loudest at the timing cover? I listened to the bottom end but everything seems quiet-but the cast oil pan muffles things a lot I'm sure. I can also hear it louder at the front freeze out plugs? The fuel pump seems quiet.I'm at a loss. Stu"
 
"Going thru thru the process o

"Going thru thru the process of elimination, which is how I do this,...can you rule out the bolt on items like you said fuel pump, circulating pump,alternator...even seen one engine the thermostat was bouncing from the missing retainer.Do you hear this noise all the time,idle,and under load?Does the noise get faster as the engine rpm increases?Are the oil pressure and water temps running normal?Would now check timing and see if it wobbles around or stays still.At this point now I would then run a compression test to check valve seats and rings.If nothing found by now I think I would pull valve covers.Off the top of my head I would proceed in this order I do believe.....Todd"
 
"Thanks Todd. I already had th

"Thanks Todd. I already had the valve covers off-adjusted the valves while I was at it. The noise is always there, rhythmic with the engine. Doesn't really change very much in volume. Eventually as you raise the rpm's the noise gets drowned out. Oil pressure is 55psi at idle. Temp 160. Doesn't make that double knock rod type sound. I agree the next move should be to remove all the accesories. Absolutely sound way loud from the timing cover. Keep you posted. Stu"
 
Might want to check tightness

Might want to check tightness on all bolts.Does noise sound tinny like the cover making the noise or much more solid?...Todd
 
"Todd, everything is tight. Th

"Todd, everything is tight. The sound is solid. Funny thing is it's there when the engine is cold, hot-nothing changes it. There is one spot-at about 1500 rpm where it disappears. Open the throttle a bit more and it's back again. Balancer maybe? Stu"
 
"Assuming you are correct that

"Assuming you are correct that the noise is coming from the timing cover area,yes it could be the balancer.Is the center bolt still in and tight?So that the balancer is not able to move in and out and hopefully not just being held on by the belts.Only thing else would be to pull the cover and look for shiny spots or wear marks.Do you know if this engine has a timing chain or is it gears?Could be they are moving around end-wise.Perhaps some others on here can share more light on this from things they have seen thru the years.Sure would like to know of anything else before pulling that cover, but if something is amiss-better to find it now before breakage..Todd"
 
"Hey, Stu, I'll bet you a

"Hey, Stu, I'll bet you a steak dinner that your "noise" is perfectly normal. (What a deal! You can't loose, right?)

Had a '57 Pontiac once that I took the fan off during the winter (so it would warm up quicker in Massachusetts). Ran it all winter that way and, long as I didn't get caught in traffic, it never overheated. And while that fan was off, the motor sounded like it was gonna blow up! (It never did.) The roar of the fan covers up all kinds of God-awful noises coming from the block.

That goes for marine engines as well.

Jeff"
 
"Jeff, I hope you're right

"Jeff, I hope you're right. I took it out for a couple of hours-believe it or not to get rid of last season's fuel!, and everything went uneventfully. I shorted out 1 cyl at a time and that changed nothing-noise is still there I spoke to a Marine engine rebuilder and he gave me a couple of suggestions.
He said that in that engine any internal noise gets muffled by the pan, manifolds and all the other bolted on junk but gets amplified by the timing cover-it acts like the head of a drum. All this adds up to it's easier to dx an engine noise in a car-like you said I'll keep a watchful eye. Stu"
 
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