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Engine Developed A Weird Knocking

govich

By govich,
in Engines & Forced Induction

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govich Community Regular

govich

Posted
Posted (edited)

Hey guys,

I started the car up this morning and it just idled roughly for a second or two and then this noise developed. It's a sort of 'knocking' noise, but im sure actual knock doesn't sound like this when revved. Sounds expensive, so i'd just like to see if anyone has ideas. I took 2 videos; one of the car idling and then in the second one i open the throttle a bit. Note the car still has good power (revs cleanly), and the fan spins cleanly (without hitting anything).

I've had suggestions including belts and bearings. Any help appreciated guys.

idling

revving

Edited by govich
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https://www.sau.com.au/forums/topic/134774-engine-developed-a-weird-knocking/
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GunMetalR33 Mentor

GunMetalR33

Posted
Posted

I have the same sound when the engine is ideling and cold. Its not as loud as that though and goes away when the engine heats up...

I have always figured that it was a big end baring on its way out, but its been doing it for a year now with no "engine go bang action"...

shanef Grand Master

shanef

Posted
Posted

Sorry to say this buddy, but u've prolly got either a)a spun big end or b)bent rod.

ill try and find the vids i took of my r33 and my gtr when they made similar noises, and ill grab the pics of what was found when the r33 was stripped down.

gtr660hp Experienced

gtr660hp

Posted
Posted
:) what did the re-build cost you?

I binned it and sold off most of the useful parts- manifolds, turbo's etc and bought another one from Japan that I knew was freshly rebuilt with JUN pistons-cost about 4k landed. If I had of rebuilt here instead Id say no change from 7k with desent pistons/rods. You can do it cheaper depending on piston/rod choice. The rebuilt one I have now has copped a huge caining and has not missed a beat :P

elbee111 Proficient

elbee111

Posted
Posted

I had this sound very recently (see the link), sounds pretty much the same to me.

Was perfect one day and sounded crook at startup the next. Had never used oil before and found that it was down to half dipstick when I checked it after the sound.

El Bee

http://www.skylinesaustralia.com/forums/in...t&p=2468684

skyguy61 Collaborator

skyguy61

Posted
Posted

I'd have to agree with El Bee, its sounds like its in the top end a few sticky lifters maybe, try listening to it with a long screwdriver whilst the motor is idling, if it is that id be flushing it first then refill fill with clean oil and filter, also might be worth a look under the rocker cover for signs of coked up oil, just my 2 bobs worth, cheers

Good luck with it hope it isnt any more serious than that.

Cubes Grand Master

Cubes

Posted
Posted

My initial thought was top end. All though I haven't heard an rb big end I can say it definitely doesn't sound like any big end i've heard before. Its too clacky sounding.

In fact the idling sounds exactly what my freshly built RB30 sounded like upon its initial start until the lifters pumped up. :)

govich Community Regular

govich

Posted
  • Author
Posted (edited)

Thanks guys, i can't seem to replicate the problem now, it purrs along just as before. I'll have to have a proper look around in the morning - i was in a rush to get to uni this morning so didn't really look at anything thoroughly.

It definitely isn't making any noise now though, hot or cold start.

edit: Oil level is fine, i'm thinking a lifter or two wasn't getting oil for whatever reason. I'll get more worried if it does it again..

Edited by govich

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