Exhaust smoke, what's about right? - PeachParts Mercedes-Benz Forum

networkboy · #1 09-14-2006, 01:30 PM

So I've been wrenching a bit on this new project of mine (83 300D Turbo, 234K) and have the acceleration power about where it feels right.

Right now, once warmed up I have a light bit of exhaust smoke. When driving I see no smoke from the tailpipe until about 4000 RPM and by 4500 RPM there is a good cloud behind me. The idle is still a touch rough (and at ~600RPM).

Does all this sound about right?

On another note, the nailing is all but gone now that I've opened it up to 4700RPM+ a couple times with a bottle or RL Catylist and 1/3 bottle of RL incector cleaner in one tank of fuel (half way through the tank).

I'll be trying for a 0-60 measurement this weekend

-nB

TheDon · #2 09-14-2006, 02:35 PM

what color smoke?

networkboy · #3 09-14-2006, 04:40 PM

greyish at idle, bit darker at full RPM.
no smell of oil or coolant, smells like diesel smoke.
-nB

#4 09-14-2006, 05:46 PM

Quote:

Originally Posted by networkboy

When driving I see no smoke from the tailpipe until about 4000 RPM and by 4500 RPM there is a good cloud behind me. The idle is still a touch rough (and at ~600RPM).

You should check your boost level and up to specs (11-13psi). You probably still have ~8psi.

Slightly higher idle at ~750rpm would make it smoother.

networkboy · #5 09-14-2006, 06:36 PM

What will increasing the boost pressure actually do (relative to performance, reliability, and economy)? As I am satisfied with the performance as is, I would like to keep reliability and economy as higher priorities.

As to the idle, I'll up it a bit after this tank is done if the added cleaner doesn't help any more (so far so good). The idle is kind of an uneven loping, I'll see if I can get an audio recording of it some time.

-nB

#6 09-14-2006, 06:49 PM

Quote:

Originally Posted by networkboy

What will increasing the boost pressure actually do (relative to performance, reliability, and economy)? As I am satisfied with the performance as is,

If you have black smoke at full power, the engine is not getting enough air to burn all the fuel. Unburned fuel increases exhaust temperatures and that's bad for longevity. Higher boost pressure is better for the engine as the extra air helps cool the cylinder.

networkboy · #7 09-14-2006, 06:56 PM

Ok, now for the obvious newbie question:
How to adjust and how to measure?

I have a vac/pressure guage I bought to start troubleshooting the vac system on this car, assuming it goes to 15PSI (I'm at work ATM) would that be OK to use, and where should I connest it at (1/8 barb fitting on the guage, but I have a ton of pnumatic fittings I can borrow from work).

As to the adjustment, I'll start searchingthe forums as it's certainly been covered, but feel like giving out a shortcut?

Finally,
Increasing the boost pressure will increase the temperature. Should I plan an intercooler for a future project, or is that more an optional bit (there is plenty of other stuff to do on this car once I have the basics done, like a full steering and suspension rebuild).

Cheers (and thanks),
-nB

#8 09-14-2006, 07:09 PM

Quote:

Originally Posted by networkboy

assuming it goes to 15PSI (I'm at work ATM) would that be OK to use, and where should I connest it at (1/8 barb fitting on the guage, but I have a ton of pnumatic fittings I can borrow from work).

As to the adjustment, I'll start searchingthe forums as it's certainly been covered, but feel like giving out a shortcut?

Finally,
Increasing the boost pressure will increase the temperature. Should I plan an intercooler for a future project, or is that more an optional bit

Boost adjustment link:
http://www.serenitysys.com/MB/Service_Info/Turbo_Tweak/tweaking_the_mercedes_617_turbo_.htm

There is a thread going right now as to an intake port to use as a boost gauge source.

An intercooler is not needed on these cars unless you adjust the full load setting inside the injection pump and/or run more than 15psi of boost. Intercoolers are nice, but it's not a weekend bolt-on project for a W123. There is a fair bit of fabrication needed to make it work well.

networkboy · #9 09-15-2006, 05:05 PM

This weekend just got really busy, I'm still going to time the 0-60 but likely won't get to anything else. I have my wife in the Camry as a chase car and she said the smoke stays grey just a fair volume of it.
-nB

winmutt · #10 09-15-2006, 05:42 PM

^^^ someone confiscate this guys shift/capslock key.

networkboy · #11 09-15-2006, 05:59 PM

Quote:

Originally Posted by bgkast

This is about the 3rd or 4th time you have posted this, and it seems a bit out of place in this thread.

Looks like SPAM to me...
-nB

bgkast · #12 09-15-2006, 07:40 PM

Quote:

Originally Posted by ForcedInduction

I've got a stem kit for next time I adjust my valves (I'll do a guide for it as well.)

Looking forward to it.

resago · #13 09-16-2006, 07:38 PM

Quote:

Originally Posted by networkboy

Finally,
Increasing the boost pressure will increase the temperature. Should I plan an intercooler for a future project, or is that more an optional bit (there is plenty of other stuff to do on this car once I have the basics done, like a full steering and suspension rebuild).

Cheers (and thanks),
-nB

fuel increases temps, turbo only really increase temps when outside their efficiency curve. Personally, I'd tune it up to 14PSI if you have a tight engine with little blowby.

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