antlee928

Hi, I have noticed, especialy after longer highway/freeway trips and more spirited Frenzies, what appears to be a residue or film around/near the exhaust exit pipe. On the S4 with standard exhaust, the exit pipe only just clears the edge of the rear bumper apron. It is not an oily residue more like a "gum" kind of film that mostly wont wash off and usually requires a clay bar or light cutting compund to remove. It is something that builds up with time and can, if left for some time, become slightly visible against a lighter exterior colour (mine is Guards Red).

Is this quite normal? Is this a pre-text of something going wrong with my engine? BTW, engine performance and economy are all ok. Have recently refreshed ful regulator, dampers, fule pump and fuel filter. Next on the agenda will be to replace injectors. Mine are original and am in no doubt their performance has deteriorated over 25 years.

Am interested in this lists observations and advice.

Cheers

Tony
928 S4 MY89

Ducman82

sounds like she is running a tad rich. hows the oil look?

Mrmerlin

this film will be more apparent with the cats removed as more dirty exhaust will be flowing on the surfaces of the rear PU.
With factory cats installed the film residue decreases a lot.

To remove it I use car soap mixed with water in a spray bottle. then a good cleaner wax

Tony

This...ive run with out them and had a yellowish brown residue that wipes right off. With the high flow cats its gone.

UpFixenDerPorsche

Hey Ant, you may have an 'oil' leak at the rear of the oil filler neck; that is at the fitting where the crankcase breather tube connects to the filler neck.

I have the same issue. Over 3000rpm the crankcase turbulence forces oil mist out the cam cover breather to a return in the filler neck.

Oil builds up in the vee and overflows down the front of the engine under heavy braking.

Droplets are then blown rearwards under the car and deposit on the rear lhs bodywork. I first thought it was a rich mixture until it got r.e.a.l.l.y b.a.d in a short time and I found a fine oil coating around the LH rear tire.

I spent hours searching the front of the engine for oil leaks and then realised it was much worse after giving a good wellie up Mt. Glorious.

Need to lift the manifold to get at the tube. Use a borescope check under there first.

Until I'm in the right mood to attack the manifold I just tootle around under 3000rpm.

HTH.

Cheers

John C.
'90GT
'89S4
'03 BMW R1100S

545svk

Both mine and my friends gt does that as well. Both white with no cats.

Dave928S

That's no fun .... I redline my 4WD every day and I can't imagine driving a 928 under 3000rpm