Jim Carmichael

Yesterday I was meeting with a friend to play Golf, and he happened to come up behind me in his BMW 540. We had a little fun for a mile or so, and he commented that I should step on it more often, as there was some "brown dust" that came off the exhaust, not black like oil burning.
We guess it is rust and crap in the exhaust system, any comment ? Thanks

Flying Finn

[quote]Originally posted by Jim Carmichael:
<strong>Yesterday I was meeting with a friend to play Golf, and he happened to come up behind me in his BMW 540. We had a little fun for a mile or so, and he commented that I should step on it more often, as there was some "brown dust" that came off the exhaust, not black like oil burning.
We guess it is rust and crap in the exhaust system, any comment ? Thanks</strong><hr></blockquote>

Most likely, it's carbon burning when you are flooring it!

You should do it more often, that will cure this 'problem'.

tom_993

Rust and crap in the exhaust system? Not likely, unless your car has been stored for a long time. Exhaust systems are made of high quality steel these days; the steel will often outlive the car. You might get a little surface rust, but that’s it. Even so, any loose stuff in there would likely be blown out during the first few minutes of driving.

I noticed you said “off” the exhaust, not “out of” the exhaust. I took it to mean “out of.” Correct me if I’m wrong. Is it still doing it? Or was it just that one time? How often do you drive the car?

Jim Carmichael

Drive almost daily when we have good weather here in Canada, but rarely go past 5500 rpm....

Greg Fishman

[quote]Originally posted by Jim Carmichael:
<strong>Drive almost daily when we have good weather here in Canada, but rarely go past 5500 rpm....</strong><hr></blockquote>

Jim,
Repeat after me.. floor the gas pedal, don't shift until redline at 6700rpm, repeat as road and license allows.
This will clear up that small problem you have, and you will get a big smile on your face. Of course your wife may wonder what you have been doing when you come home with a "permagrin".

Seriously, try to use the car as it was intended, I usually run the car to redline at least once everytime I drive it long enough for the oil to fully warm up. You won't hurt her.

Greg

Mike J

While I do agree that these engines need to be run out how do you guys manage to do this and still keep down to a safe speed? Redline in 2nd gear gets me to very fast and I would argue dangerous speeds on a city street?

I do the occasional DE but most of my driving is in the city. And I don't drive like an old grandma...but doing 50+MPH on a small city road with lots of sidestreets is dangerous, no?

Mike

tom_993

You can safely get to redline in second getting on the freeway (use a straight on ramp!). Getting to redline in first is easy.

Regular runs to 5500 would certainly blow any loose rust and crap out of the exhaust system, so I don’t think that is Jim’s problem.

Tom
'95 993

Flying Finn

[quote]Originally posted by Jim Carmichael:
<strong>...but rarely go past 5500 rpm....</strong><hr></blockquote>

Yep, there's your 'problem'!

Steve Weiner-Rennsport Systems

[quote]Originally posted by Jim Carmichael:
<strong>Yesterday I was meeting with a friend to play Golf, and he happened to come up behind me in his BMW 540. We had a little fun for a mile or so, and he commented that I should step on it more often, as there was some "brown dust" that came off the exhaust, not black like oil burning.
We guess it is rust and crap in the exhaust system, any comment ? Thanks</strong><hr></blockquote>


Hi Jim:

That brown dust your friend saw was simply the byproducts of burning unleaded fuels that had been deposited inside your exhaust system being blown out.

Not to worry. The mufflers & heat exchangers are made from stainless steel and the internal rust buildup is very minor.

Now then,...all this advice about "stepping on it" hard once a day (or more) is good input and will go a long way toward controlling the carbon buildup that these are prone to do.

No matter what, follow that up with regular treatments of Techron or LubroMoly and you'll be in fine shape,......

H20NOO

Jim,

I'm backing Steve's assessment. Burning oil produces white smoke. Fuel and/or fuel additives produce brown or black smoke.

Matt

Anir

Jim,

The owner's manual does specifically advise keeping the revs under 4,000 rpm until the engine is warmed up, and I'd try to stick to this.

However, once the engine is warmed up, I'd agree with frequently taking it up above 5500 rpm. I try not to run the engine for extended periods at less than 3,500 rpm, by staying in a lower gear (and thus making a lot of beautiful noise for all those around me! ).


Thanks to Steve's excellent recommendations, I also routinely use Lubro Moly additives (Jectron and Ventil Sauber together, every 4-5K before an oil change), and often notice increased brown/black smoke as this runs through the system, as Matt pointed out.

Enjoy that beautiful car! It will thank you for it.

Jim Carmichael

Thanks all, I will try and not get a ticket !