And some more from Chat GPT , regarding the question in the thread :
A metallic
ticking sound on the left (driver’s) side of a 1971 Chrysler Newport with a
383 big-block is usually caused by something in the valve train, exhaust, or accessory drive. Here are the
most common causes, starting with the most likely:
1. Exhaust leak at the manifold (VERY common on 383/440 engines)
A leaking exhaust manifold gasket or loose bolt creates a
sharp metallic “tick”, especially noticeable at idle and when cold.
Symptoms:
- Tick speeds up with RPM
- Often quieter when engine warms
- Soot around manifold ports
- Slight “puffing” feel if you put your hand near the leak
The driver side manifold on big-block Mopars is known for warping.
2. Loose rocker arm / worn rocker shaft
The 383 uses a shaft-mounted rocker system. Wear on the shaft, loose bolts, or excessive valve lash can make a
light metal tick.
Symptoms:
- Consistent rhythmic tick
- Louder when the valve cover is off
- Sometimes misfire or slight loss of power
3. Collapsed or sticking hydraulic lifter
Even though the 383 has hydraulic lifters, they can collapse or gum up with age.
Symptoms:
- Tick that comes and goes
- Louder when cold
- May quiet down at higher RPM
4. Worn cam lobe
A flattened cam lobe causes a
duller tick and reduced valve lift.
Symptoms:
- Slight rough idle
- Power loss
- Tick doesn’t go away warm or cold
5. Loose spark plug
A spark plug that is loose or cross-threaded can make a
very metallic tick, almost identical to an exhaust leak.
Symptoms:
- Strong exhaust smell near plug
- Soot on threads
- Tick changes when you lightly tighten plug
6. Fuel pump arm noise
The mechanical fuel pump on the 383 is on the left side. Its actuating arm can tick if worn or not seated properly.
Symptoms:
- Tick is louder near the front of the engine
- Changes with RPM
- Often misdiagnosed as a lifter
7. Accessory or pulley noise
Less common, but possible:
- Alternator bearing
- Power steering pump
- Harmonic balancer beginning to separate
These usually make more of a
chirp or
grind than a tick.
How to narrow it down quickly
A. Use a mechanic’s stethoscope (or a long screwdriver).
- Listen at the valve cover → lifter/rocker noise
- Listen at exhaust manifold → leak
- Listen at fuel pump → pump arm
- Listen at alternator/pulleys → accessory bearings
B. Cold vs. hot behavior
- Quieter when warm: likely exhaust leak, lifter pumped up, or loose rocker
- Same hot or cold: likely rocker wear, cam lobe, or accessory
C. Quick test for exhaust leak
- Block the tailpipe briefly with a rag → ticking often gets louder
- Or spray soapy water on manifold edges (cold) → bubbling = leak
If you want, I can help you pinpoint it:
Tell me:
- Does the ticking change with RPM?
- Does it go away or improve when warm?
- Is it loudest at the front, middle, or rear of the engine?
- Any recent work done on the engine?
With that, I can narrow it to 1–2 likely causes.