GappySmeg Posted September 12, 2016 Share Posted September 12, 2016 Yikes, this is a new one on me, so I'm going to struggle to explain it well... bear with me. During a "spirited" drive, all was well until the car started making a very bassy grumble under hard acceleration. So bassy the grumble that I thought for a while the exhaust was blowing at one of the headers... but having stuck my head under the bonnet and rev'd it, I don't think it is that now. Moderate acceleration is fine, but give it some beans in 1st/2nd/3rd and this grumble manifests. Car had been thoroughly warmed up by the time this started, and due to the warmth was starting to do it's "floppy clutch" party trick... could it be related to this?!? The only thing I can think it could be, is a knackered DMF... but having never experienced a knackered DMF, I'm just guessing. Anyone have any thoughts? Quote Link to comment Share on other sites More sharing options...
brillomaster Posted September 12, 2016 Share Posted September 12, 2016 'grumble' is a strange adjective... we're used to whirring, hissing, clunking, whining, but grumble just sounds like the missus is unhappy with your driving style! does the noise change with engine speed, or road speed, or neither? might be your exhaust is starting to split near the back box, that would start getting a lot louder and bassier, and would be related to engine load as well as engine speed. Get a friend to rev the car while you're inspecting the rear of the exhaust, I suspect engine noise would mask exhaust noise if you rev it yourself while under the bonnet. Quote Link to comment Share on other sites More sharing options...
GappySmeg Posted September 12, 2016 Author Share Posted September 12, 2016 just sounds like the missus is unhappy with your driving style! Well, that's a given Grumble/rumble is about the best description... could honestly be mistaken for a bass-line kicking in... if only the Bose amp/sub was good enough to be the source of the noise! Going to wait for the car too cool down, then go out again and see if it's still there... struggle to believe it's an exhaust noise though as it doesn't really come in gradually or change pitch with engine speed... it literally comes on like a switch if the acceleration is aggressive enough, and goes away equally swiftly when the ceasing acceleration. Will go out again and get more info. Quote Link to comment Share on other sites More sharing options...
GappySmeg Posted September 12, 2016 Author Share Posted September 12, 2016 Hmm.. went out again, car cold so no more floppy pedal and lo and behold, no more grumble/rumble under v.hard acceleration. Naturally I had to do LOTS and LOTS of 2nd/3rd gear full-throttle-to-red-line tests, just to be sure Don't know whether to be relieved, or even more worried... Quote Link to comment Share on other sites More sharing options...
-G- Posted September 12, 2016 Share Posted September 12, 2016 I always love the whine my 380RS diff makes when I'm applying power & miss it when I have to back it off - it sounds like your grumble is appearing under the same condition? Can't hurt to check/replace the diff fluid at the next service, anyway :-) Quote Link to comment Share on other sites More sharing options...
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