Technical chevy 292 engine noise, need help?

my chevy straight six 292 motor is making noise, it seems to be coming from the front of the motor but i cant pinpoint it.

i checked the valves and they are all tight, i also checked the exhaust manifold and its nice and tight as well.

i also checked the alternator belt, it is tight too, i loosened it a little but it still made the noise.




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any tips on what this could be?

thanks in advance,

mike

 

I'd pop the belts off and fire it up for long enough to tell if the noise was coming from the water pump or alternator or anything else belt driven. That will either tell you it is one or the other or it is internal in the engine.
O'Reillys and Autozone sell a mechanics stethoscope for under ten bucks that is great for isolating noises. I use mine all the time hunting noises.
https://www.oreillyauto.com/detail/...e/w80582/4614519/1998/bmw/528i?q=stethoscope+

 

I guess you're talking about the clicking noise that sounds like it needs a little valve adjustment?

 

Stock fan? Cracked fan blade? Maybe remove the fuel pump and run it for a few seconds.

Do you have a good steady vacuum at idle?

 

i took the belts off, started it up and the noise was still there.

the fan is original, 1950 chevy, no cracks in the blade, looked perfect.

i didnt try the fuel pump removal, its a brand new fuel pump, not that means much i guess.

i dont know how to check steady vacuum, but the car idles just fine.

maybe i need to adjust the valves again, i forgot how to do it.

loosen them all up, tighten them all back up, plus 1/4 turn?

the car has been sitting for about a year, but i think the noise was there before.

 

Hydraulic lifters? GM always went 1 turn past touching-zero lash (not one turn past "not ticking"). I always wimp out and go 3/4 turn past zero lash.

Solids would have a intake and exhaust spec after engine is warmed...not just coolant temp, but heat soaked. You can set them running, it'll just curl some feeler gauges a bit.

 

Tighten the 3capscrews holding the pulleys to the harmonic balencer. They should be at minimum grade 5. I have used grade 8 and used a 1/2" drive breaker bar to get them tight enough. I can't tell if it's in front or on top. But most 292's had hydraulic lifters so there should be no noise from them.

 

That noise is the lifters.

 

yes, i have hydraulic lifters. the pulley on the harmonic balancer is very tight.

after i entertain the little lady i will go out to the shop and take another crack at adjusting the valves and let you know how it went tomoro.

thanks a lot guys.

 

Valve lifter adjustment, or an exhaust leak. What's underneath the header wrap? I am Butch/56sedandelivery.

 

there is nothing under the header wrap except the headers? is there supposed to be something between the wrap and the headers? i wrapped them up because i didnt want to see the eventual rust.

so i went out to the shop, popped off the valve cover, loosened all the rockers nuts so the rocker arms are all loose now. i rolled the motor over to TDC. then i started to google, search the hamb, youtube etc and now i am more confused because there are so many different opinions on how to set the valves.

some say to do it with the motor running spitting oil all over the place, others say thats not required. i have an old valve cover i could cut the top off if doing it with the motor running , but i think the job can be done without the motor running, but i dont know diddly.

can someone tell me how to do it? i follow instructions really well, and i know how to turn a 5/8" socket like a pro.

i'll get this done one way or another.

 

I've had 2 of those engines in pickup trucks. Even the worn one was pretty quiet but my dad usta drive a 65 chevy with a 292 that had a busted piston. I swore that thing was going to ****ter all over the road but it never did. Was a knocking sound that was louder under acceleration and loudest when it was cold.

 

That' one way to set the valves I suppose. Hahahahaha. I'll bust the piston, stick it in a truck and take it Alaska where it's colder than texas.

I love the hamb and all you guys but that takes the cake.

 

Miky, if they are hydraulic, I bet they need to be set just as the Buick does. Both valves closed, adjust until just the slack is taken up, then a set amount of preload. Again, if hydraulic, probably one is not staying pumped up. Find that one and repair/replace.

Ben

 

With both valves closed on #1 cylinder, adjust the nut to zero lash, then go 3/4 turn more.
Rotate engine by hand till #2 cylinder valves are closed, adjust to zero lash + 3/4 turn,
Etc............ till all six cylinders are adjusted.

It's a lot of rotating, much easier then jumping around the head.

 

i tightened all the rocker nuts per the procedure, but when i got to the number 2 exhaust valve it was way off, wouldnt tighten. i fired it up anyway and thats what was making the noise.

so i pulled the pushrod cover off, i noticed the top of the pushrod was chewed up a little. i pulled out the lifter and it looked fine. i put it back in and put the pushrod back in and now it tightens up just fine. i turned the motor over and the lifter goes up and down as you would expect.

im gonna go get a new pushrod and see what happens.

what do you think happened here? maybe the lifter collapsed and now its back to normal?

thanks again,

mike

 

A lot of guys are under the impression that header wrap actually CAUSES rust, and rust out UNDER the wrap; that was my reasoning to," what's under the header wrap?", could there be rust through? Sixes usually use a "common" gasket for the intake and exhaust/header manifold (s). usually the header flange is't very thick; could it be warped and not sealing, leading to a blowout/exhaust leak? Valve adjustment or exhaust leak is still my guess. I am Butch/56sedandelivery.

 

the headers are brand new and not leaking, l listened with a hose to my ear.

as i said above it was the lifter on exhaust valve 2, but im not sure why, about to put it back together and see what happens....

 

After sitting for a year...probably just stuck... drive the snot out of her and dump some oil down the carb. My cure will either fix it or wear it out...

 

i turned the motor over a couple of times and now i am back to square one. the rocker arm nut on exhaust valve #2 wont tighten. i could see the lifter go up and down when i turned the motor. i took the lifter apart and i could see nothing wrong with it.

so i thought perhaps the valve was stuck open? i tapped it gently with a big hammer, it felt springy, like its not stuck, i figure if it was stuck it wouldnt feel "springy"?

at this point i am lost and am at the mercy of you guys.

 

Dang, that hole in the PR looks eaten out quite a bit.

Did you see if it's oiling?

I'd take a look at the inside of the rocker arm as well. It may have the same wear as the PR.

 

If the nut will not tighten, it is possible that the stud is loose where it is pressed into the head. If a valve was stuck the stud may have pulled up. Try to hammer the stud down. If it moves it is loose. There were oversized shank studs made to repair this. Or you can drill and pin the stud in place.

 

yes indeed, this pushrod is damaged, i am getting a new one tomorrow, the rocker arm looked fine, no damage.

the stud also appears to be fine, did not seem loose and is is the same height as all the rest.

 

I thought the end of the pushrod looked "worn" also; a little "bright", and the oil hole enlarged. I had an issue with a rocker arm stud pulling out on a K-5 Blazer with a 350 many years ago. After driving it back in a couple of times, I pulled it completely after lowering the coolant level. With a cold chisel, I scored the shank some (not a lot, and not deep), cleaned the stud hole in the head, used some red loc***e (all I had), coated the stud and hole, and drove it back in (used a poly lock nut and br*** hammer). Let it set overnight with a space heater blowing at the stud, readjusted the lifter, and called it done. Ran fine for the rest of the time I had the thing. Years later, I found it in a used car lot, and it was still running fine; all beat up, but running fine. I am Butch/56sedandelivery.

 

i went out to shop again and pulled out all the push rods to have a look see.
as it turned out, i discovered that the #2 exhaust valve push rod was not just worn a little, it was actually 3/8" shorter that what it should be. so i guess it was either way to loose (or tight?) and was just getting hammered around for a while.

this explains why i couldn't get it tightened up, and of course explains the noise i was hearing.

im gonna get 12 new push rods and start again. im crossing my fingers that everything will run smoothly when im finished. i will pretend to myself that the shavings created by the disintegrated push rod just magically disappeared and went bye bye and wont cause me any problems, what else can i do at this point except change the oil.

 

Has the push rod still got both the balls on the end ?? If so some body has put a shorter push rod in at some time.

 

It' hard to tell since it' so work but that' possible

 

put a scratch mark in the top of the stud. Then turn the nut 1/4 turn and see if your mark moved. If that's good take thee nut off and check the threads on the stud and the nut.

 

Would that be about the difference in pushrod length between a 250 and a 292?

 

i got all new pushrods just to be safe, i went thru the valve adjustment procedure:

turn the motor until cylinder #1 exhaust valve starts to open, set the intake valve, turn the motor until intake seats, and so on thru the firing order: 1 5 3 6 2 4.

i went to 3/4 turns after zero lash.

everything tightened up nicely as i did it, but i notice that some of the rockers are very loose as i turn the motor over. is this normal? i have an old valve cover i cut the top off, so i am gonna go try to fire it up and see what happens.