23-12-2012, 12:26 PM
I had a look today and I am fairly certain that it is the downpipe. I revved it to the rev range where it makes the noise and a small puff of exhaust fumes came from somewhere (I couldn't determine whether it was the downpipe or not) but that is the area where the sound seems to originate from, which would also make sense because it is more noticeable in the cabin.
Fairly pissed TBH as I am sure I did that up properly when I put in the new manifold gasket but I guess the wire gasket on the downpipe hasn't seated properly which is quite possible since I had to have the engine wedged forwards with a block of wood to work on it. I think the pressure noise higher in the rev range is due to the exhaust gases escaping from the leak which is confusing as I thought the exhaust gases where free flowing, i.e. not under pressure. There is also a possibility that the main sound at low revs is caused by one of the washers on the exhaust bolt rattling if the nuts have worked loose.
Fairly pissed TBH as I am sure I did that up properly when I put in the new manifold gasket but I guess the wire gasket on the downpipe hasn't seated properly which is quite possible since I had to have the engine wedged forwards with a block of wood to work on it. I think the pressure noise higher in the rev range is due to the exhaust gases escaping from the leak which is confusing as I thought the exhaust gases where free flowing, i.e. not under pressure. There is also a possibility that the main sound at low revs is caused by one of the washers on the exhaust bolt rattling if the nuts have worked loose.