Technical Strange sound??

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Technical Strange sound??

Joined
Aug 2, 2009
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114
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Location
Surbiton
Just got back from Tuscany with my X1/9..covered 993 trouble free miles (put the car on the motorail service from den Bosch, Holland to Livorno for the main chunk of the journey). Mileage is up to 11086 now. Had a real blast driving it in Italy-if I got a Euro for every admiring glance I got (at the car, not me!) I would be a millionaire..Must admit though after long motorway miles it was a bit like sitting in a BOOM box with the noise from the full CSC system especially with the roof on. It was made worthwhile though by dropping a gear or two and flooring it through long mountain tunnels!
ANYWAY, the reason I write is I wonder if anyone can explain a noise I continuously encountered during the trip..it happened at high speed (60 and up) after the car had thoroughly warmed up so could be heard mostly on motorways. It seemed to be coming from under the floor pan and is best described as a metallic, cracking sound..seemed like it was caused by heat? It wasnt much different from an engine when it 'pinks'..in fact it was quite similar to that. The performance of the car was in no way affected. Any ideas anyone? (Jimbro?). I was thinking it may have something to do with the cooling pipes running the length of the car under the floor.....Thanks (I had never experienced the sound driving in England)
 
There isn't an awful lot under the car to make any kind of noise except the pipes and the gearshift rod.

If it sounded like heat expansion/contraction then it may well be as you've assumed and it is the metal of the pipes moving slightly as they get thoroughly warmed up but it must have been getting *very* hot for that to happen which is a little worrying in itself.

The CSC exhaust system does a similar trick but I would be impressed if you can hear it in the cabin. This was my major gripe with the CSC exhaust, despite being painted in VHT paint (allegedly) it still burns off which means the exhaust is getting stupidly hot.

In terms of finding the noise you've been hearing it is going to be a cat and mouse chase to isolate it. If you can only hear it while the car is in motion and only when in a hot environment (I'm guessing it just isn't warm enough in the UK?) then this is going to be a real toughie.
 
Thanks for your thoughts on that Jimbro. I thought as much. As it isn't actually causing a problem I don't think I'll worry about it too much. The car didn't overheat at all including during a 10km climb up to Volterra in 36 degree heat-it did get bloody hot though and when I opened the engine cover after parking up, there was quite a bit of smoke pouring out of the breather tube!
Goes to show though that if the cooling system is in good order and well maintained, you do not need a second fan nor a thermostat which opens a few degrees cooler nor any other fancy mods I've read about on this and other forums.
 
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