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Opinions. what is this noise.
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Author:  qwerty123 [ Mon Mar 02, 2015 3:24 pm ]
Post subject:  Opinions. what is this noise.
hi guys,

standard g13ba with 204,000km has recently been making this noise,

very loud when cold at idle and under load.

once hot it is barely audible and seems fine,

only started once i changed the oil (New 10w40) no idea what the previous owner had in it. And now i just tried 20w50 and it makes no difference.

Ive adjusted the valve clearance to spec and it seems to go away a bit when i pull an ignition lead. but still audible.

it seems to be getting worse. my gut tells me rod knock but it goes away when hot. very confused.

no knock when rolling in gear

Image
Author:  jdk81 [ Mon Mar 02, 2015 6:38 pm ]
Post subject:  Re: Opinions. what is this noise.
Id guess a spun bearing
Did you fill the oil filter prior to installing, when doing the oil change?
Running dry for a bit can be enough to cause it, especially on an old engine

It may be something simple, but not fixing a spun bearing asap may ruin the whole motor
Author:  qwerty123 [ Mon Mar 02, 2015 6:56 pm ]
Post subject:  Re: Opinions. what is this noise.
i suppose what your saying is possible. but it didn't happen straight away it took about 100km of driving to show up.

also dead cold if i pull #3 lead noise disappears
Author:  jdk81 [ Mon Mar 02, 2015 7:06 pm ]
Post subject:  Re: Opinions. what is this noise.
So id consider its the bearing on conrod 3.
Author:  qwerty123 [ Mon Mar 02, 2015 7:15 pm ]
Post subject:  Re: Opinions. what is this noise.
Rod bearing or main crank bearing?

From what i have heard rod knock should get worse/louder when hot as the oil thins out. I'm sure the main bearings follow these same rules.

This is the part that is confusing me and makes no sense.

thanks for your input
Author:  jdk81 [ Mon Mar 02, 2015 7:36 pm ]
Post subject:  Re: Opinions. what is this noise.
Check my build thread.
The block with the holes in it went bang.

Was a light knock and didnt sound like a typical bearing issue.
Didn't change when it got hot etc.

Another block had a funny sound as well (not typical), and its bearings were kinda rooted too. It wasnt far from exploding too.

Rod and crank bearings werent expensive
Author:  qwerty123 [ Tue Mar 03, 2015 7:30 pm ]
Post subject:  Re: Opinions. what is this noise.
Update.

pulled the pan to have a look. everything seems fine,
I tried to move the conrod up and down and could not get any sound,
only when i moved them side to side

here is some pics they are worn but is it enough to knock??

bottom
Image

top
Image

crank
Image
Author:  jonno_racing [ Tue Mar 03, 2015 10:44 pm ]
Post subject:  Re: Opinions. what is this noise.
Gudgeon pin knock then?
Author:  qwerty123 [ Wed Mar 04, 2015 6:17 pm ]
Post subject:  Re: Opinions. what is this noise.
definitely not wrist pins, they are solid,

along with everything else the bottom end looks mint, pistons and bores are perfect (can still see hatching)
top of the pistons are absolutely carbon free. (borescope through spark plug hole)

no sludge nothing in sump
ive ordered new rod bearings and will see if it makes a difference
I'm starting to wonder if it is head related as i always thought it was coming from #3 exhaust port area, no leaks though

also starting to wonder if its been rebuilt previously. are the sumps sealed with RTV or cork from factory
Author:  qwerty123 [ Wed Mar 11, 2015 8:49 pm ]
Post subject:  Re: Opinions. what is this noise.
Just fitted new rod bearings,

No difference.

It has to be piston slap or valve related.
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