Re: Hello - and help!
Hi OneFiveSix and welcome,
I dont have a 1.8 at the mo but maybe can shed some light on your ailments:
1 - The front end clatter could be caused by aftermarket pads that are slightly smaller than the OEM ones and therefore rattle in the caliper which would stop whilst you covered the brake, but also possibly worn guide bolts, simple test, jack up, wheel off, move pads up and down if they are fine attempt to move outer half of caliper about.
2. Had a similar problem on a V6 Mondy, the internals of the CAT had collapse causing too much back press hence strangling the engine. The hissing could be this back pressure escaping through a corroded/split seam.
Hope this helps
Previous Italian Cars:
10 Alfa 159 SW 2.0 JTDm Lusso, 57 Fiat Grande Punto 1.2 360 Active, 08 Alfa 159 SW 2.4 JTDm Lusso, 07 Fiat Grande Punto 1.4 Active Sport, 53 Alfa 156 SW 2.4 20v MJet Veloce, 99 Alfa 156 2.0TS
530i and 59 Cinquecento Lounge (the little lady's)