Problem with 2008 Honda Civic EX Coupe 2D

A problem has started with my son’s 2008 Honda Civic EX Coupe 2D, and with which I would appreciate some advice.

When completely cold, the engine on starting sounds very loud, a bit like an aero engine. On warming up however, the engine noise returns to normal. This problem apparently started quite suddenly, a few months ago. It is difficult to express a sound in words, but if the normal engine makes a Vrooom sound, then the sound when cold is more like an Aaaaaarrrr. I lifted the bonnet, and looking at the engine compartment, the sound seems to eminate from the left hand side of the engine block.

I did notice that when accelerating from a Stop sign just after starting the car, that I could here the engine revving up over the Aaaaarrrrr noise, and it seemed to be normal. Sorry, it that sounds confusing.

For reference, I am a qualified Engineer, but have little experience in car repairs. My practical knowledge goes as far as changing the battery, spark plugs or oil/air filters.

We will take the vehicle to a shop in a few days to see whether they can diagnose the problem. If not then we will take the vehicle to the Honda dealer. Before doing so however, I wanted to get some experience from the community, in order to not go in unprepared.

Any advice would be much appreciated.

A Happy New Year 2015 to all.

Thank you.

Are you an EE? Most cannot tie their shoes without illustrated instructions. A high pitched whine could easily be a belt squeal. Maybe a bad tensioner pulley. Bad alternator bearing and so on

Is this the noise?

I’m assuming there are no dash lights, no check engine light, etc. If so, first order of business, be sure to double check the engine oil level. A Vrrooom sound can be caused by an exhaust system leak. The leak could be at the transition from the exhaust manifold to the exhaust pipe for example. Or a leaky gasket between the exhaust manifold and the cylinder head. Sometimes as the parts warm up they expand and seal the leak, in between the noise can transition to a ffft ffft fffft sound, until it goes away entirely as the engine warms.

There are at least a dozen other causes though. I guess if my Corolla had this problem, after checking all the fluid levels were ok, I find a length of garden hose, use it as a stethoscope, and see if I could isolate more exactly where the noise is coming from.

Thank you to Cavell, Insightful and GeorgeSanJose for their responses. Funny comment about EEs. No, I am an Automation Engineer working on Oil and Gas development projects.

The problem turned out to be with the clutch assembly. I foolishly forgot to mention that the vehicle has a manual gearbox in my original posting. Anyhow, the car is now in a transmission shop.

Thank you all once again.

Thanks for the update.