fubar

(I would really appreciate any comments/suggestions from you experts before I go to a mechanic)

Subura Gurus...

Here's one for you experts to try and diagnose:
I have a strange noise that's recently started coming from my engine.

Car is MY99 Turbo with Scoobysport downpipe, de-cat centre + Remus backbox + ITG Panel filter.
No other mods.

Noise only appears under VERY hard accelaration.
Most noticeable in 1/2/3 gears but happens in all to a degree.
No loss of power - car does not feel as if it is slowing down or stuttering.
Occurs about 5000 rpm - sometimes lower sometimes higher.
Best description is it sounds like someone quickly brushing a snare drum with one of those wire drumsticks.
Sound occurs on and off quite quickly for a few seconds then disappears at peak revs.
Exhaust/Filter mods were installed fine, and no noise initially - it started a few weeks ago for no apparent reason after mods on car for 3 or 4 months)

I've taken a Subaru mechanic for a spin in the car who could not identify the noise as something he had heard before. (Said it wasn't det though.)
Car was recently serviced, and noise remains.

To my untrained ear, I'm suspecting something boost related - it seems to occur under maximum boost conditions (I think).

My suspicions:
Panel filter loose?
Over-boosting (what happens to excess boost pressure - could dump valve / wastegate be problem???)

Was even suggested by mechanic it could be bodywork vibrating - but seems to consistent to be that I think.

I appreciate these are hard to diagnose remotely, as sound is very subjective - just wondered if there is a top 10 checklist for common noise problems.

Thanks for any suggestions.
Ian.

P20SPD

iTrader: (1)

Did you put your heatshield back on after the SS downpipe?

P20SPD

iTrader: (1)

Forgot to say, if so, check that all the bolts are tight. My money is on the heatshield rattling! (thats if its on)

Had this a few times before.

fubar

Aaahh .. might just be it.
Scoobysport installed the downpipe, so I think they trim and re-install normally - is that right???
Downpipe is lagged - does that make a difference to whether they re-install the heatsheild or not?
Can I visually see the heatshield with the bonnet up?

nom

Hi Ian!
Noises are great to describe, aren't they?
Is it more metallic or airy sounding? I ask 'cos wire brush against a drum is a bit of both!
Heatshield rattling is quite noisy - I think? More buzzing as well?
Another thought... turbo getting 'off balance'? I've heard one doing this before, but it was a roller-bearing rather than sleeve-bearing & sounded more whistley than what you're describing. So you should be OK there!
Umm... is it definately coming from the engine end?

nom

Heatshield's the thing to the left of the intercooler with the 'do not touch' hand on it! It's hot...
There should be - I think - 3 (?)bolts on there if Scoobysport did the job. Normally 5, though.
ait for a few hours after the car's stopped running though until looking!

Tim Bomford

I would have said Det based on the noises I've heard when mine did it. Its like a can full of nails being shaken....

Whats your car as I work in Amersham?

Tim

fubar

Hi Tom,

I would say it was more metallic than airy.
The noise definitely comes on and off quite quickly.

- I don't suppose you're passing Amersham / Slough way any day soon again are you - could take a minute just to have a quick listen if you were :-)
Not whistly in my mind, and pretty sure its front end related.

fubar

Tim - noise is not det - it's more quiet/buzzy/zingy than that.

Whereabouts in Amersham are you?

Fancy having a quick listen ?
- Would be very grateful if you could!

Mailme: fubar@bigwig.net if you could spare a minute to have a listen to it.

Tim Bomford

I work at Amersham, next to the White lion (on White Lion rd!)

On late shift next week so could meet you one evening then if you like?

Tim

P20SPD

iTrader: (1)

if its metal sounding, i still think its the heatshield, thats why i put 5 bolts back in and not 3, it should not rattle then.

nom

Ian - I might be - I'll let you know when if it isn't sorted! But I think it's probably heatshield as well - nice & easy to fix

fubar

Tim: OK let me check out the heatshield, and I'll let you know.

Steven/Tom: Thanks for taking the time to reply - very helpful.

Ian.

P20SPD

iTrader: (1)

no problem

fubar

FYI ... the noise was getting slightly worse / louder over the weekend.
Then this morning on M25, becomes evident that the exhaust started to blow badly (really badly). Seems one of the bolts connecting downpipe to centre section had worked itself loose.
Guess initial noise was some exhaust gas escaping when accelerating hard, and then eventually a bolt comes loose and downpipe and centre are no longer connected properly - that certainly made some noise until I just got it sorted out this afternoon.

Anyway - this is one of those noises that has been fixed!

nom

Good to know it's sorted!