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304 Holden 5.0L Engine Knocking

st11xy

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Hi all,
I currently have an issue with my 5.0L Caprice.
When i start the car it has a slight knock coming from somewhere in the engine and as the revs build up the noise gets faster and a little bit louder... Thinking it could be bent rod, rockers or lifter or even something else?
Any ideas guys n girls??
 

Nitro

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Hi all,
I currently have an issue with my 5.0L Caprice.
When i start the car it has a slight knock coming from somewhere in the engine and as the revs build up the noise gets faster and a little bit louder... Thinking it could be bent rod, rockers or lifter or even something else?
Any ideas guys n girls??
not disrespecting your judgement but are You sure its not a ticking sound? as a knock would rule out the valve train :)
 

Darren_L

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very difficult to diagnose without hearing the noise.
Is it a deep knock or more a rattle ?
Does it seem to be coming from the crankcase or higher.

Unusual for a bent conrod unless the engine has taken in water
If it's a bottom end knock, it's more likely to be a bearing.
 

immortality

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How long since the last oil change? What grade of oil are you using?

Could just be a noisy hydraulic lifter but as mentioned without hearing it, it's almost impossible to say.
 

IRON8

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please more info!!

- when was the last oil change
- how many k's on the clock
- does it sound like its from the font, back, top or bottom of the motor
- does it go fully away when warm
- loss of power?
- smoking?
- any pullies wobbling?

- the list goes on..

info info info
 

someguy360

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Depends if its a knock or a tick/rattle.

My 5L had a bit of a knock....was a big end bearing.

Ticking will be more top end/valve train.


Best way to know for sure is to hook an oil pressure gauge up and have a suss....

When I hooked an oil pressure gauge up to mine it showed 30psi on a cold start but after 2-3 minutes of running it dropped off to about 0.5-1psi at idle and 5psi under revs, once I pulled the motor the bottom end was trashed.

Spinning bearings is common on the 5L's when they haven't been properly maintained over the years or used cheap nasty oil for too long....sludge builds up and blocks the undersized oil pickup in the sump and leads to starvation of oil to the engine.


It could also be your harmonic balancer, inspect it for wobbles or play
 
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BlackoutSteve

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Other clues to consider are..
Is the noise at engine speed, or at 1/2 engine speed?
Are your exhaust manifold bolts tight or if headers, possibly a cracked primary?
Is the noise only present when cold? Piston-slap for example..
 

someguy360

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Arrr hahahaha no-one noticed the thread date !!!! :rofl2:
Lol, I had no idea didn't look.

new members always do this :/

Seems to be a JC ritual, new members first posts always have to be digging 2+ year old threads up haha
 
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