Topic: is it junked?
in Forum: C3 Engines
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Well, here's a new one for me:
Hmel '74 2007-10-04 03:28:26
2 weeks ago I was coming home from a vette show and was cruising around 55 mph and I bumped it up to about 75 mph. after that, I heard a ticking (or possibly a tapping sound) coming from the motor.
I could only hear this when i was travelling at the 30-45 mph range. (it might be heard above that but my chambered exhaust doesn't allow me to hear much of anything above 45 mph 
).
).Now the car ONLY does this AFTER IT IS WARMED UP and only when accelerating or decellerating above 30 mph. you cannot hear any tick or tapping at idle.
other than the noise, it runs fine and there is no obvious change in power.
I pulled the valve covers off to see if there were any loose/broken rocker arms or possibly bent pushrods but it all looks good (from my eye anyway).
any thoughts, ideas, suggestions about this before I end up dropping in a new motor???
btw, I have a gear drive on it and it almost sounds to me like it could be the gear drive chattering???
thanks, jeff
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
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It could be the gear drive set-up, but it would make the noise all the time, not just when hot.
It is more than likely a lifter noise, if it is actually coming from the engine.
Can you rev it up(in neutral) and hear the noise at all, or do you have to be driving/moving?
Does the car have headers?
Automatic or standard trans?
Mechanical or electric fuel pump?
Does the noise seem to be rpm related, or vehicle speed related?
Is it a "heavy" or "tinny" sound?
Tastes great, or less filling?
(sorry...that one slipped out...
)
Might be the fuel pump push-rod if you have the mechanical pump still...
It is more than likely a lifter noise, if it is actually coming from the engine.
Can you rev it up(in neutral) and hear the noise at all, or do you have to be driving/moving?
Does the car have headers?
Automatic or standard trans?
Mechanical or electric fuel pump?
Does the noise seem to be rpm related, or vehicle speed related?
Is it a "heavy" or "tinny" sound?
Tastes great, or less filling?
(sorry...that one slipped out...
)
Might be the fuel pump push-rod if you have the mechanical pump still...
Joel Adams
C3VR Lifetime Member #56 
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Joel,
well, let's see:
i can hear it when i rev it while standing at the motor and pulling the throttle linkage (only when it's warmed up though).
the car is an automatic.
mechanical fuel pump. (it is the stock fuel pump setup).
no headers on the car.
the sound is rpm related (since i can hear it while it's sitting there).
i'd say it's more of a "tinny" sound rather than a deep heavy sound.
oh, and i'd say "less filling"
wouldn't a lifter noise be constant from the initial start-up? and not only after warmed up?
Hmel '74 2007-10-04 06:58:59
well, let's see:
i can hear it when i rev it while standing at the motor and pulling the throttle linkage (only when it's warmed up though).
the car is an automatic.
mechanical fuel pump. (it is the stock fuel pump setup).
no headers on the car.
the sound is rpm related (since i can hear it while it's sitting there).
i'd say it's more of a "tinny" sound rather than a deep heavy sound.
oh, and i'd say "less filling"
wouldn't a lifter noise be constant from the initial start-up? and not only after warmed up?
Hydraulic or solid lifters?
When was the last time they were adjusted?
Do you have a long handled screw driver you can use as a listening device?
Could it be coming from the exhaust?
Can you tell if it is driver's or pass side?
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Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
A lifter can make noises hot or cold, or both. Depends on the type of "failure" it may have.
Dave has a good idea about trying to isolate the noise to one side or the other. Long handled screw drivers will work by placing the tip against the engine, valve cover, water pump, etc, and the handle end against your ear. This helps to narrow down the area the noise is coming from.
Exhaust leaks, if from a cracked manifold, will usually be loud when cold, and get quieter as the manifold heats up, but an exhaust leak can often sound exactly like a lifter ticking.
Another thing to look for is the outer ring of the harmonic balancer slipping towards the rear, and rubbing on the timing cover. This can make a ticking noise at first, and then turn into a grinding noise as it gets really bad.
See if you can get a long screwdriver on the fuel pump, and listen to see if the noise is coming from there. It could be the pump itself, or even the push-rod worn on the end(s). I've seen that happen a few times, and it is a pita to locate the noise...
Dave has a good idea about trying to isolate the noise to one side or the other. Long handled screw drivers will work by placing the tip against the engine, valve cover, water pump, etc, and the handle end against your ear. This helps to narrow down the area the noise is coming from.
Exhaust leaks, if from a cracked manifold, will usually be loud when cold, and get quieter as the manifold heats up, but an exhaust leak can often sound exactly like a lifter ticking.
Another thing to look for is the outer ring of the harmonic balancer slipping towards the rear, and rubbing on the timing cover. This can make a ticking noise at first, and then turn into a grinding noise as it gets really bad.
See if you can get a long screwdriver on the fuel pump, and listen to see if the noise is coming from there. It could be the pump itself, or even the push-rod worn on the end(s). I've seen that happen a few times, and it is a pita to locate the noise...
Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
in Forum: C3 Engines
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