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304 knock--- Need help!!

Discussion in 'VN - VP Holden Commodore (1988 - 1993)' started by Vp304ute, Feb 10, 2019.

  1. Vp304ute

    Vp304ute New Member

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    Gday guys
    New to the forum so would love your help. I've searched this forum and Google all over and haven't found a solution or answer to my problem, only threads that weren't completed, so thought I'd start a new thread.

    I've recently bought a VP s pack 304 factory auto, completely stock other then extractors to my knowledge. I picked it up pretty cheap so no complaints there but I'm having a few issues with her atm. The issues I'm having regard to 1. Flickering or solid oil pressure light on idle and 2. An engine knock that presents itself once warmed up (I'll get to that one).

    Regarding the pressure light. When I bought the car, the light didn't present itself until the car was warmed up, and only appeared on idle as a flicker. The warmer it gets the more solid the light becomes. I thought that it would probably be the infamous oil pump issue, so since I've brought it home, I've replaced the oil pump (it was in need of replacing btw), removed and cleaned the sensor multiple times, threw in some 20w 50 and a bottle of engine cleaner. Now after I'd done all that, it appears nothing has changed!!! Pulling my hair out!!

    Regarding the knock it too only presents itself once the engine is warmed up. Sounds perfect when cold. The knock only happens when in 'park' or 'neutral' position, and happens AFTER I rev it, from 1500rpms and down to idle. So I rev and sounds fine then as it winds down from 1500rpms down it has this knock. I've watched plenty of videos, heard many theory's, listened to it over and over, under the car, front of the engine.... I think it doesn't sound engine, maybe torque converter, but old man reckons it might be big end bearings.

    So I'm interested to hear what you guys have to say, or tests that I can do to narrow it down. It's in really good condition so don't want to part ways with it, but if it's serious I might have to with the budget I have. Would love to hear from you guys
    Cheers
     
    Last edited: Feb 10, 2019
  2. someguy360

    someguy360 Well-Known Member

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    The bottom end bearings are toast mate.

    Bottom end is worn to the point that theres no oil pressure when warm hence why your oil light is flickering, a rebuild or replacement engine is your only option. Theres no real band-aid for this one unfortunately.

    I lost one of my engines to the exact same symptoms a few years ago, big end bearing was knackered.
     
    Last edited: Feb 10, 2019
  3. MikeC

    MikeC Member

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    If you have silvery metal particles in the oil your bearings are gone. Get to them early enough and you might get by with a new set of bearings - still a big job. Leave it too long and the crankshaft will be destroyed, it this happens a good second hand engine is the best option.
     
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  4. VS 5.0

    VS 5.0 Well-Known Member

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    Fixed it for you.
     
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  5. EYY

    EYY Well-Known Member

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    I just pulled one apart that was quiet when cold but started tapping when it got warm. Turned out the oil pickup was seriously clogged with sludge and silicone.

    Good second hand engines are hard to come by now at decent prices. Work with the one you already have imo.
     
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  6. _R_J_K_

    _R_J_K_ Well-Known Member

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    I'd also say replace your oil pressure sensor as an eliminator for the light, but it does sound like your two issues are related.
     
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  7. Deuce

    Deuce Super Stock

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    That sound is the sound of your engine crying out to you for more power.
    Give it what it wants and pull the motor for a refresh and a hot up.
    MORE POWA!!!!
     
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  8. Vp304ute

    Vp304ute New Member

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    Last edited: Feb 10, 2019
  9. Vp304ute

    Vp304ute New Member

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    100% agree with that one. It is a pain to do that so might be a while before I get the time to check that out but that would be good if it was but not getting my hopes up.... Cheers for the responses too boys. I'll check back with any updates.
     
    Last edited: Feb 10, 2019
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  10. someguy360

    someguy360 Well-Known Member

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    It's not really as simple as just replacing the bearings, the crank journals likely won't be the best and you will most likely have tiny metal shavings all through the engine.

    Your only option is a rebuild or a 2nd hand/reco engine. Once the bottom end lets go enough to start knocking the damage is done, if you keep running it every second that engine is turning is hurting it more and more too. If it gets worse the engine may seize or go boom at that point it's beyond rebuild.

    If you are choosing to go down the rebuild route the more you run that engine the more it's going to cost you. It only takes 30 seconds without oil pressure to destroy an engine and every time that oil light comes on you've lost oil pressure.
     
    Last edited: Feb 11, 2019
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  11. Vp304ute

    Vp304ute New Member

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    Mmmm good info thanks mate... It's not registered atm so it's not going too many places. Got quoted 250 to machine the crank if it's no good by my local machine shop, so just gotta find the time to pull it down.
     
  12. delcowizzid

    delcowizzid on holiday

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    If you stop driving it now it's probably savable but soon the bigends of the rods will go out of round and you won't get away with fitting bearings and going again.once they go out of shape they need to be closed and honed meaning they shave a small amount off the mating surface of the caps then hone the hole back to size .its cheaper to buy new rods than get them fixed lol
     
  13. rambunctious

    rambunctious Well-Known Member

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    Check it is not a fuel pump knock or dip stick knock.
     
  14. Brettly-2008

    Brettly-2008 Active Member

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    I'd get the short rebuilt properly (consider stroking it even). While that's being done, strip and service the heads yourself and assemble the long yourself with full new gasket kit, you'll save a heap, plus you've already got a new oil pump. Under $5k all up potentially.
     

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