i was with some friends dicking around, hit it at 30 in 1st gear...brought it just a lil too far ...bout 5000 rpm....and now my motor is making a peculiar noise in the front; at first i thought it was an accessory, but im not too sure.its almost like a mixture between a loose rocker sound and a head to header exhaust leak...its a thud...not a tick like lifters...well maybe a low pitch tick.....and its near the front...its not a bearing noise either...any ideas?...could a bent pushrod cause it....maybe did i somehow mess up the valve and hit the piston? but if it hit the piston how would you explain the sound....any ideas old wise men??

 

take the belt off and see if its still there

 

How's it run? A bent pushrod would probably make you run like ***...

Do what he said....that will at least eliminate pulley bearings as the cause. Just watch you don't overheat w/o the belt.

 

alright took the belt off and stsarted it...not a single thing changed....im thinking it isnt a bent pushrod because it still pulls hard and idles fine..no studdering or anything...i tried playing with the valve lash a lil bit but there wasnt any difference...any more ideas?

 

Theres so many noise-making parts in an engine man....at this point it's making wild guesses.

If you can get an engine stethoscope, do so. It might help you pinpoint at least the AREA it's coming from.

 

Mine's making a similar sound, only louder.
It sounds like the ehxaust is blasting straight out of the port. Sort of like an unmuffled 2 stroke motor idling at 1500rpm. Except the exhaust is in good shape on my car.
My neighbor gave me the car in that condition, and then moved away, so I can't ask him about it.
I'm thinking it's a severely spun bearing. As if it was spun then he continued driving it anyway. and it got so loose that now the piston is hitting the head.
The oil is the color of a chocolate milkshake.
It's a lot louder than a rod knock tho. Tomorrow, I'll take the heads off.
I'm thinking it could be a head gasket that's blown toward the outside of the motor, but I doubt it, I've never seen that happen.
Might be a hole in the piston too.
Possibly a combination of things.

If you bend an intake valve, it will make a popping sound that from the drivers seat, sounds like an exhaust leak. But if you remove the air filter, you'll hear it popping through the carb on every firing stroke, and it'll disappear if you pull the plug wire on the offending cyl.

 

Streetiron, if you have chocolate milkshake in your oil pan, then you most likely have a head gasket problem. Look in your radiator to see if you also have oil contamination in the coolant.
If so, do not drive the car. Start taking it apart so you can replace the bearings, before you throw a rod through your block!
Seen it happen only about 8 times in my life. Once on a 3rd gen.

 

When I got my car it was disassembled, down to the heads. I put it together and fired it up just today to try an figure out what it might be, and that was the sound it made.
There wasn't any coolant in it when I got it.
It might be that the head gasket blew and that was followed by a spun bearing.
I definitely won't be running it.
I have a fresh engine in my garage that I'll probably end up putting into it.

This isn't my thread, but thanks for the help anyhow.

 

Mine sounded similar last summer and it turned out to be the fiberglass cam gear, all the teeth but a couple here and there were gone. Replaced with a new timing chain & gear set and everythings fine now. I also took the pan off and checked my bearings before I found it. It sounds between a rod knock and a loose rocker, right? And if its coming from the very front, could be your timing set as my timing chain was actually hitting the cover.

 

if it sounds like its directly in front of the engine and center....check the base timing. If the timing is jumping around at idle then could be slack in the timing chain makin noise. also look closely at the balancer see if the metal ring slipped or is loose and making noise.

 

Maybe a broken valve spring?

Only taking it to 5000 shouldn't break anything though... 6000+ maybe, but not 5000.

 

i guess it may be the timing chain thing. but it is weird, the car runs perfectly fine. idle jumps a lil once in a while but it has done that forvever. what would a bent exhaust valve do?also the noise is fairly consistant, it does not sound at all random

 

Mine idled a little funny and the sound was constantly there. And all I did was to start it to go to work and it started knocking. It might not be the timing chain, I would pull the valve covers and watch the rockers and the valve springs as it runs. At least that way you can rule out the top end. If your lucks like mine, its never the simple things that go wrong.

 

i did have to pull the covers when i messed around with the valve lash...that made no difference in the sound

 

I had the same thing happen to me 3 times in my 18 years of driving. I was getting on it and all of a sudden there was a "POP"! and the engine sounded real bad and had a miss. Turns out that 2 times I had blown the ceramic portion of the plug through the threaded portion of the spark plug.

Maybe your plug is loose or about to break. I also had a 91 Z31 (3.4 OHC) and It had what I thought was a bad lifter. One day while changing the oil, I started the engine to curculate the new oil. After it got oil psi, I reved it up while leaning over the motor, and a loose plug shot out of the engine about 3 inches past my head so fast that it landed in the front yard of a neighbors house 2 houses down, and the plug wire smacked my brother in the chest and gave him a big welt.

Check your plugs, you might get lucky.

 

I didn't read all of the replies... but here's my .02...


1. Check oil PSI... if you are low on oil... or your pump ate it, your lifters will collapse and begin ticking

2. Check header/manifold gaskets.... a blown out gasket can often sound very similar to a lifter/pushrod.

 

Is this noise RPM-based (fluxuates with RPM levels) or is it independant or RPM loads? Im assuming it varies with RPM.

Like johnyIROC stated, what is the oil pressure at?

Check the timing if you have a gun. What is the base timing at (not what it is set at, but what is it firing at?)

If you go to the store, grab a length of heater hose. Stick it in your ear like me and probe around. The heater hose has the same effect as a automotive stethoscope. If you can pinpoint the sound, you can narrow it down.

Check your PM's

 

You can find out how much slack there is in the timing chain by taking off the distributor cap then turning the motor by hand, first one way then the other, and watching the rotor on the dist to find out how much crank rotation there is before the slack is taken up and the rotor begins to move.
My guess is that it isn't the timing chain.
A compression test would tell you if it's (or isn't) a bent valve.