Engine Noise

[slow ginn]

Looking for some advice here guys. I've noticed when my engine is hot, (M400 service less than 1,000 miles ago, total mileage 4,800) at idle I hear a 'camy' like 'top end' rattle. As soon as I blip the throttle this disappears. Oil level is fine. Is this something to worry about? I was hoping to do an evening session at Silverstone next week but don't want to wreck my engine. What does anyone think? Also what is 'heat soak' I hear you all talking about as being a particular problem for Nobles?
Thanks.

[obes]

I would get that looked at if I were you mate, could be something really minor (which is most likely) or it could be something inside

Heat soak with regard to Nobles is a problem where the intercooler gets to a temperature where it an no longer effectively cool the charge. You need your intake temperature as cool as possible as it makes the air more dense and therefore more 'explosive'. You can see huge losses in go as it all heats up as the engine management cuts power as it detects the higher intake temp to prevent overheating.

Noble 12's/400's suffer from it as they don't really get much air where the intercooler is, even at speed. (you mat have noticed that if you get leaves on the rear clam, they'll still be there after a drive)

Edited by obes on Thursday 27th July 09:44

[chillidog]

slow ginn said:

Looking for some advice here guys. I've noticed when my engine is hot, (M400 service less than 1,000 miles ago, total mileage 4,800) at idle I hear a 'camy' like 'top end' rattle. As soon as I blip the throttle this disappears. Oil level is fine. Is this something to worry about? I was hoping to do an evening session at Silverstone next week but don't want to wreck my engine. What does anyone think? Also what is 'heat soak' I hear you all talking about as being a particular problem for Nobles?
Thanks.

Look for broken exhaust bracket - in which case fix it soon.

Also check the front turbo heat shield which is a common source of rattles - if this is the source and it's not broken then don't worry about it (maybe just bend it up a bit).
--
RIchard

[nickytwohats]

I had a really scary noise at the "top" end - turned out to be a lose A/C compressor...

[joust]

I'd get it looked at, they aren't meant to make any strange noises.

J

[paulcundy]

My crankshaft failure first presented itself by making a very light tappy tinkling noise between 2-2,500 rpm only. Got louder and louder during the drive home from Bedford. By end of trip was an "obviously something wrong sort of tap".

Early 5 speed gearboxes had a layshaft rattle in neutral cured by speeding up the idle.

Exhaust bracket and front turbo as stated are regular sources of rattles.

Turbo bolts and manifold bolts loosen but that should be a blowing sort of nooise.

Regards
Paul C

[SFM]

Hi, Slow Gin
I`ve got a 3R [6200 miles] mine is the opposite, when I start up from cold, I have a similar sound, further investigation found it coming from the water pump pulley and pump.
Squirted them with silicon belt spray and noise stopped, but only for a short while. When engine is warmed up noise disappears totally, untill engine is cold again. I just put it down to expansion/contraction of the components.

[gadgeroonie]

get an oil pressure gauge fitted

i've seen this before on cars that run very thin synthetic oil

when its hot its even thinner - can you run thicker oil ?

[V6GTO]

Don't suppose it's a thrust bearing is it? Mine in a wee bit noisy at times.

Martin.

[slow ginn]

Thanks all.
Not heat shield or exhaust bracket nor thrust bearing(noise would disapear when clutch in?)
Maybe layshaft noise or as gadgeroonie suggests oil too thin/hot.
Guess a visit to Plans to check it out a good idea!
Thanks for advise.
Regards
Gaius
any news on Dunsfold day Paul?

[paulcundy]

slow ginn said:

any news on Dunsfold day Paul?

No none, I enquired again earlier this evening.
Regards
PauL C