Hi guys!

Attached is a video of an engine rattling when coming down to idle/revving. Car has no CEL and drives perfectly fine and makes great power. Feels better than previous s2000s I’ve driven.

Any idea on what this rattle could be? TCT, tensioner and idler pulley bearings brand new. I have checked valves and exhaust is perfect at .254mm but I just came to the realisation the intake was .203mm which was really tight with the feeler gauge. I am thinking the intake valves might be a tiny bit too tight as they should be .21mm? The rattle goes away when revving/driving.

The car also has this hum/buzz at around 3500-4500rpm regardless of throttle position or cruising. Feels like it’s coming from the transmission tunnel. Doesn’t have a heat shield and have checked all the bolts/header and notorious bolt/flange. Have also checked if there was an oil cap wedged between gearbox. Has an invidia decat too so not loose insides either.

The main concern is the rattle on idle/when revving/letting revs drop to idle but appreciate help for everything else. I hope the specialist Billman can help too

 

Video of buzz at 4000rpm when accelerating regardless of throttle. I have pinpointed the buzz within the video (not the deceleration clutch buzz)

 

Take another video. 5 feet away from the front of the car, hood closed.

It is the only way individual noises will be picked up and stand out.

 

What brand of TCT used?

Is it possible its the lost oil cap issue? Notorious for lost cap to get stuck on top of trans, rattles around making noise. Fix is get ubder and reach around to top of trans and fish it out. Exact description of where to feel around is in a thread somewhere. Just search for S2000 lost oil cap transmission

 

Tight valves are quiet and since your valves are not "perfect" (they're tight) the noise probably isn't valve lash.

As for your settings note valves tighten in use so the recommendation is to set to MAX cold clearance. Further recommendation is to set the exhaust to "one thousandth (inch) over" or 0.012" especially for the DBW cars which run lean but this "loose" is fine for all cars. 0.012" = 0.3048mm rounded to 0.30mm or "one hundredth (mm) over."

OEM Spec
Intake: 0.21-0.25mm (0.008-0.010in)
Exhaust: 0.25-0.29mm (1.010-0.011in). Fine to bump to 0.30mm or 0.012in.

Note valve clearance is done on a cold engine. 100°F/38°C. Just bringing the car in from outdoors will exceed that temperature.

-- Chuck

 

Will get one tonight or tomorrow as soon as possible

 

An Australian equivalent of Billmans one that has been modified.

I’ve checked for the oil cap as well. I was 90% sure it was that too but couldn’t find anything. Will need to try again just to double check

 

Thank you. Confirming the test was done on a cold and left over night. It’s parked indoors though so you’re saying needs to be over night outside so it doesn’t exceed 38 degrees?

The engine is an f20c so I think the exhaust clearance is ok, but intake is I feel a tiny on the tight side. I believe the video below also has a similar sound (albeit mine isn’t as loud):

Will try get more videos for everyone and do some more diagnosing. All videos from previous issues are all deleted so hope we can keep the holy grail of information going

 

Ok, for the video, CLOSE the hood and hold, don't move, hold the camera about 5 feet in front. That is it for the video someone else took with the hood open is not helpful.

As far as valve adjustment goes, don't worry about the temperature. The engine needs to be stone cold; that is the engine has been off for some time. Maybe drive it in the morning, park it, and by the NEXT day the engine will be cool enough for adjustment. You should be able to put your hand on the engine and think: This engine has not been running at all.

 

Will definitely get a video with hood closed from 5 feet away when I get the chance.

Okay can confirm when I checked valve clearance car was stone cold and not driven for a day and a half and parked in a garage. Will get back to everyone asap and appreciate the insights so far