Low Down Rattle In My 26

[GTAAAH]

My 32 GTR recently developed a fair rattle in the head (sounds like it's coming from just behind the timing belt cover, but it's not a belt as it goes quieter with rev's and isn't a ticking noise), it goes quieter with more rev's, it's very noticeable at idle but at like 3.5k+ it's quiet.. I can't notice it under load at all

It as plenty of oil in it (motul 2100)etc, always has.. It used to happen a bit quieter but it went away for a while and is back now.. My oil pressure gauge is reading a bit low too but it's always been a bit dodgy, reading high sometimes and low at others so i dont think it's a pressure prob.

What could it be? Most of the people who have spun bearings etc notice it more up top but this is only down low and only in neutral..

Not sure about K's on engine but i know it was replaced about 20,000 km's ago..

thx

Edit: found a 33 with same prob.. suggestions were "A/C compressor bearing" and "timing belt idler or tensioner pulley bearings".. Still confused as to why it would only be at low revolutions and not under load if it was one of these :S

Edited January 7, 2008 by GTAAAH

[T04GTR]

umm. a rattle is very hard to diagnose without knowing where it is. using normal 15 dollar 20w-50 oil in a 26 is abit alarming. when you listen to it at idle slowly bring the revs up by hand. it may get louder,

worst case its a bigend, at the other end its some fan belt issue or a loose fan.

[GTAAAH]

the 2100 was $70 and i think it's 10w-40 or something from memory i think you've mixed it up with something else

I bring the rev's up from idle and it's probably loudest just above idle, i keep bringing it up and it gets drowned by engine noise at about 3.5k and from their upwards nothing.. I'm a bit weary to take it to a mechanic without opinions because i have discovered alot of dodgy ones and the ones i trust aren't too good on newer cars

The main thing that doesn't make sense to me is that it doesn't keep getting louder with rev's

Edited January 7, 2008 by GTAAAH

[Beer Baron]

get rid of the oil. switch to the motul chrono 400V. 10W40. much better choice. well after you've diagnosed the problem that is.

problem could also be a loose balancer like mine

[GTAAAH]

ok i will throw it in next oil change... which will probably be tonight, i didn't think so many things could make the same noise may have to drive it out to brooklyn to get it checked.. so far to drive.. thx ppl

hmm... $4200 for a new 26 isn't bad either..

Edited January 7, 2008 by GTAAAH

[GTAAAH]

ey, it was just a bearing inside the air conditioner unit, lucky! i was scared it was big end or something, tuner said my engine is vry healthy otherwise