Noisy engine

[BROKINBIMMER]

Fresh valve adjustment, fresh oil, new exhaust w new high flow cat and new muffler. Unable to determine if a leak is present, but motor is very loud from outside car and from inside while driving....Should I pull the exhaust manifolds and replace the gaskets/studs/nuts?

[jlevie]

Not until you find out if that is the source of the noise.

[dnguyen1963]

It depends on the type of noise you are hearing. High flow Cat and muffler can increase the exhaust noise ten folds easily.

[EatsHondas]

Fresh valve adjustment, fresh oil, new exhaust w new high flow cat and new muffler. Unable to determine if a leak is present, but motor is very loud from outside car and from inside while driving....Should I pull the exhaust manifolds and replace the gaskets/studs/nuts?

Suck in Seafoam through the vacuum hose that runs from the intake to the regulator. You'll smooth your idle and initial throttle response, and white smoke will seep out of any exhaust leaks you may have. I didn't know I was leaking out of the downpipe(s)/manifold connection until I did this.

Stock cats are very restrictive (9 bhp difference according to BMW http://en.wikipedia.org/wiki/BMW_M20) and quiet the motor considerably. High flow cats combined with a new muffler SHOULD make your engine considerably louder, and it's usually thought of as a plus.

[nickmcc92]

X2 on seafoam.
My valves are adjusted to .008" not spec .010" because my car's 25 years old.

[BROKINBIMMER]

Suck in Seafoam through the vacuum hose that runs from the intake to the regulator. You'll smooth your idle and initial throttle response, and white smoke will seep out of any exhaust leaks you may have. I didn't know I was leaking out of the downpipe(s)/manifold connection until I did this.

Stock cats are very restrictive (9 bhp difference according to BMW http://en.wikipedia.org/wiki/BMW_M20) and quiet the motor considerably. High flow cats combined with a new muffler SHOULD make your engine considerably louder, and it's usually thought of as a plus.

Good to know, did replacing those gaskets quiet it down a bit?

Also, spent yesterday replacing exhaust manifold gaskets and new manifold hardware.

[EatsHondas]

Good to know, did replacing those gaskets quiet it down a bit?

Unfortunately I don't remember hearing any difference. The car didn't run any differently/better either. All I got was the satisfaction of there being one less thing wrong with my car. :|