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Discussion Starter · #1 · (Edited)
Todays competition "WTF is that noise"?
Most noticeable between 1200 to 2800 rpm under load - reduces and eases off between 3000 - 6000 rpm and 'off-load' on trailing throttle.
Kinda hoping some of you 'old school' race guys will comment.
Background - 489 cu in BBC. Hot oil pressure 35/40 psi idle/70/80+ psi cruise. Less than 2000 miles after new build. Flat tappet hydraulic cam - fairly aggressive opening and closing ramps on cam - so it is on noisy side (but made worse by phone mounted next to valve cover on firewall. Definately not valve gear related. Sounds a bit like an 'big end' going but appears to be higher within engine. Has always had good oil pressure. Inspected cam, lifters and pushrods - all UK.
Best heard with speakers or headphones!
 

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I had similar noise on my mates Buick V6 , sounded like a big end but more rumbley than knocky . Got worse with heat and distance. Struggled to replicate it when engine wasn't under load In the end I bought a stethoscope and extended it so I could listen to the engine from the passenger seat while he drove . After gaffer taping it to various resonant areas I concluded it WAS big ends. Dropping the sump revealed big ends worn on one side only hence more of a rumble than a knock.
 

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Discussion Starter · #3 · (Edited)
I had similar noise on my mates Buick V6 , sounded like a big end but more rumbley than knocky . Got worse with heat and distance. Struggled to replicate it when engine wasn't under load In the end I bought a stethoscope and extended it so I could listen to the engine from the passenger seat while he drove . After gaffer taping it to various resonant areas I concluded it WAS big ends. Dropping the sump revealed big ends worn on one side only hence more of a rumble than a knock.
Kinda thinking towards that myself Kev - I've probably been 'fooled' by the fact that engine has always had good oil pressure (like high oil pressure) - with just one journal affected perhaps there isn't the normal expected drop in pressure? - 'sounding' the engine with ear on end of screwdriver held against cylinder no.3 inlet/head junction picks up some noise - which perhaps would point to second journal back and no.3/4 ends? - thanks for comment Kev - its appreciated and exactly what I wanted!
 

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The noise on the V6 sounded more mid engine as well , around the lifter valley area. However taping the stethoscope to the valve covers confirmed speed of noise as engine revs and not valve train. We then wedged it against the block at sort of crank midline and sure enough that's where it was . Look you screwdriver kept saying higher up. It was a cheap medical 'scope from E Bay , cost about £5 , well wort the money.

The cause of end failure on the V6 was oil filter breakdown, a Cooper unit if I remember correctly , it has clogged the oil pick up with cotton fibre. It was hanging down like a combover and more engine speed pulled it up against the gauze . The crank was really quite badly worn to the level where you'd expect it to be beating its brains out but it was only worn on one side .
 

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While researching my oil pump I found the general consensus was high oil pressure is worse than low oil pressure. Yours seems fairly high, cruise should be somewhere around 65psi.
High pressure causes cavitation on the journals (iirc) and actually leaves less oil film than lower pressure - so you may have a damaged big end which is being masked by the high pressure?
 

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What engine oil And filter are you using?
Sounds like a big end but doesn't sound quit right!
Little end may be, but again doesn't sound right!
If you can drop the sump and have a look for metal in the oil.
Does it sound louder at start up or with engine warm?
 

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Discussion Starter · #10 ·
What engine oil And filter are you using?
Sounds like a big end but doesn't sound quit right!
Little end may be, but again doesn't sound right!
If you can drop the sump and have a look for metal in the oil.
Does it sound louder at start up or with engine warm?
Millers Classic 20-50 mineral. Generic Summit Racing filter - not Fram as there were issues in past with these Stateside.
I would have thought little end would be noticeable when engine decellerating?
Noise is much the same cold or hot.
Odd that is has a definate rev range where its at its worst - higher revs and it decreases!

Guess I'll pull oil filter and cut open - drain-off oil and inspect and remove sump for 'further inspection'
 

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+1 for big end.

Are they Brodix heads as they are bound to have caused big end failure? I could do you a favour and take them off your hands if you like:incheek:
 

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Its a tough call listening to a video and not hearing it in the flesh but that does sound a lot like a motor I had that wiped off one inlet lobe on the cam. The banging was coming from high up in the engine which was caused by the piston being down the bore before the inlet started to open. That noise also changed at different throttle positions and load. It might be worth checking the lift at the rockers is the same on all cylinders.

Bob
 

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Discussion Starter · #15 · (Edited)
Its a tough call listening to a video and not hearing it in the flesh but that does sound a lot like a motor I had that wiped off one inlet lobe on the cam. The banging was coming from high up in the engine which was caused by the piston being down the bore before the inlet started to open. That noise also changed at different throttle positions and load. It might be worth checking the lift at the rockers is the same on all cylinders.

Bob
Not too sure that you mean by "piston being down the bore before inlet started to open" ? - couldn't really check lift on rockers as its a hydraulic cam. Visual check on cam - lobes all appeared fine - no irregular wear patterns - same with lifters - all visually fine.
 

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Discussion Starter · #17 ·
+1 for big end.

Are they Brodix heads as they are bound to have caused big end failure? I could do you a favour and take them off your hands if you like:incheek:
Ha! - sound like a 'reasonable' assumption! - guess I'll just have to 'junk them' and go source a new pair - hey, do us a favour - can't be asked to run them down the scrappy for salvage money - take them away for me please lol!
 
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