911sc - suddenly deeper/louder engine noise

Hi,

this is weird!!

the engine noise, from idle and throughout the rev range has become much, much, much throatier / deeper / louder.

this seems to have happend quite suddenly!

the car is a stock 1978 Euro 911sc, 3.0 ( no aircon. )

I have fitted a K and N panel air filter. BUT this was months ago, iand there was no noise increase when I fitted it )

Had a look under the car and can't see an surprise holes in the exhaust system.

9/10 times this extre noise is fine, sounds much, much sportier.
But on longer journeys it's begining to get very opressive!

Anyone any ideas what could be causing this deeper noise? ? ?

[Rot 911]

probably one of the baffles in the muffler broke off

[marcesq]

Sounds (not trying to be funny) like a baffle came loose or there is a hole yet undetected.

If your car has an air pump check the connections from the air rail to the pump, and the connections between the ERG valve and the muffler and air box.

Let us know.

[john walker's workshop]

is it coming out the tailpipe, or elsewhere? hopefully not a broken head stud. you could pull the lower covers and have a look. a piece of hose in your ear acts as a stethoscope. have a listen around the engine.

THanks guys,

will have another look tomorrow ( it's 2am Uk time at the moment! ).

noise sounds like it's coming from the tailpipe - so just as if I've fitted an aftermarket sports exhaust!


the rear silencer ( muffler ) big sausage shape was fitted recently and externally looks sound.

secondary one ( runs along the side ) doesn't look quite so new tho'.

[Bill Douglas]

Your've blown a hole in an exhaust gasket somewhere?

[Joe Bob]

If it burbles when letting off the gas while going down a hill....exhaust leak or vacuum leak.

[Superman]

I don't think it's a leak in the exhaust. I think the guts of the CAT have come loose and fragmented. I really liked the sound of my engine when the CAT was gutted.

Also, if those guts turn sideways, they can plug the exit hole in the CAT, greatly restricting your exhaust and making your car run like a Yugo.

[BernieP]

I had the same symptoms on my Euro 911SC. Turned out to be the connection at the premuffler near the muffler had rusted through and was leaking. At first I thought it was the gasket as you could feel exhaust gasses with your hand but when I unbolted the mufler it almost fell apart in my hands. Sounded good though. Good luck.