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Discussion Starter #1
Hi all,

Have noticed a metalic type sound ( like worn cam) from my rb25det when cold. It goes away complelty in about 3 mins, once the engine has warmed a bit.
Oil pressure is good. The only time its not there when cold is on the overun after a little throttle is applied,( less load) ie while the revs are dropping back down to idle. (car stationary,hand on throttle linkage)
After 3 mins or so the noise goes away. any ideas?
 

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have you got forged pistons in there? When cold forged pistons dont actually fit the bore so well its only when they heat up they expand slightly to seal properly so the noise you hear could be the pistons "rattling" about
 

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Discussion Starter #3
No I don't AFAIK, I never noticed this before, I've had the car since the summer, but not used it yet.
Had another listen last night, started the car, and let it idle. From cold it took about 3 mins to disappear.
Just before it quitened down totally, it got gradually milder, and before the noise went completey it was 'there-not there (few seconds intervals)-there- not there', noise stopped thereafter (if you know what I mean )

does it sound like a sticking tappet?

I was thinking maybe oil grade could be too thick? damn weather is a bit cooler now, from when I got the car. Car has only don't small miles since in from Japan, (mot) not on the road just yet. It's got the same oil in it from Japan, intend changing it before the car is put on the road .
 

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more than likely you have a couple of broken exhaust manifold studs and its starting to blow on the gasket.
 

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I had this problem, sounded like cams a idle, but would stop if revs raised slightly, turned out to be a worn Cambelt Tensioner.
 

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Discussion Starter #7
Checked the manifold studs, and could only find last stud (nearest bulkhead) broken. I pulled it out with my finger. I got the remains out with a bit of drilling and an easyout.
The rest appear to be intact.

But the noise is still there,
oil change next to see what happens.

Car had a cambelt change according to the cambelt cover 6kkm ago, took the camcover off, but can't really tell if the idlers are good.

Noise is there when you hold light revs, or when revs are increasing, but not when the engine revs are decreasing.

Once engine has warmed a little the noise is gone.

Oil pressure is over 4 kg/cm3 @ 2000rpm, over 2 at idle, engine at normal running temp.

Someone must have experienced this problem? :wtf:
 

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going through this with mine i've yet to try this but check that all your belts are tight ie power steering alternator an so on this is what richard at rising sun recommended i'll be giving it a try this weekend if i get time then i'll let you know
 

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Discussion Starter #10
Kez- yup replaced the stud.

Ivor- Does your noise go away after a few minutes also, and when cold noise not there on over-run?

This car is not on the road yet, had some hassles with de-reg papers..sorted now. So will be getting it reged shortly, and ready for the road. ( i hope) :dance:

Waiting 'til i can get some silkolene pro s 5w/40.

If the oil doesn't sort it.. I'll have to remove lower cambelt cover, for a better peep at the idler etc.

A bottom end problem would tend to cause a rattle when the oil is hot and thinner ? no ?
 

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i would go for 10w 60 for the oil. my noise started around about a week ago it starts at 2500 rpm i was getting good oil pressure from a greddy gauge until his morning when it only went to 2kg from cold so i checked the oil level and found it was just touching the dipstick. filled her up and i'm still getting the rattle above 2500rpm but not on decelaration so i'm going to try the belts if this don't cure it i'll be doing cambelt and tensioners
 

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Discussion Starter #12
Well did the oil and filter change, silkolene 10w50. The noise is still there though, although when I checked lastnight was not as bad, can't be sure if this is due to the oil change or not.


Took off the cambelt covers, but I can't see anything strange.

Spend a lot of time making a puller to remove the bottom pulley. Didn't release the tension off the cambelt yet to check how smooth the tensioner and idle are running, but I can't feel any play in these when I try shake them.


As i said noise can be heard from idle up to a few thousand rpm, but not on the overrun from a few thousand rpm. Higher than a few thousand rpm it's hard to hear whether it's there or not. It's there for about 3 mins when the engine is cold. Just before it stops it's 'there'-'not-there', for a few second invervals, then 'not there' therafter until the next coldstart.
 

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did anyone ever find out what it was

this sounds just like mine as soon as the engine has warmed up for a few minutes the noise goes

anyone?
 

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did you find out what this was honkongphoi? over on the other thread i have a sound recording, could you have a listen and tell me if it is a similar noise?

Cheers
Dazzler
 

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mine does this noise too, but mine is more a tuck-tuck-tuck as if something rotating. i keep thinking its worn bearings in the alternator - thats next job ;)
 
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