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Speed,Combat,Scale,Racing => F2C CL Team Race => Topic started by: frank mccune on October 13, 2016, 01:43:09 PM

Title: Black exhaust goo?
Post by: frank mccune on October 13, 2016, 01:43:09 PM
     Hi All:

     I was running my MVVS D7 today and the exhaust goo was jet black! I adjusted the needle valve and backed off the compression to where the engine was under compressed and missing.  No matter what I tried, the exhaust goo was sill very very black!  The engine started very easily and ran flawlessly.  Could it be bad fuel? Any suggestions?

                                                                                                    Tia,

                                                                                                    Frank McCune
Title: Re: Black exhaust goo?
Post by: john e. holliday on October 13, 2016, 08:26:42 PM
What fuel mix are you using?  I know from experience that over compression will cause some black crud to come out, also old kerosene.  The kerosene should be clear like tap water.
Title: Re: Black exhaust goo?
Post by: Russell Shaffer on October 13, 2016, 10:28:51 PM
If you are using a muffler, a loose one will make lots of black stuff from aluminum wearing.
Title: Re: Black exhaust goo?
Post by: Motorman on October 22, 2016, 11:34:54 AM
If you are using ether from a spray can it has a top cylinder lube in it that burns at a very low temp and comes out black as coal even if your engine is rich and undercompressed with a light load prop. It's not a problem but your engine will coke up a little faster.


MM
Title: Re: Black exhaust goo?
Post by: RknRusty on October 22, 2016, 05:47:37 PM
If you are using a muffler, a loose one will make lots of black stuff from aluminum wearing.
A rattling through-bolt in the muffler will do it too. So will one or more loose engine mounting bolts. Black exhaust goo is always alarming, but I hope it turns out to be something simple just vibrating.
Title: Re: Black exhaust goo?
Post by: frank mccune on May 27, 2017, 09:55:08 AM
     Hi All:

     I found the problem and corrected it.  The rear of the rod was rubbing on the crank disk.  I filed the rear of the rod for adequate clearance.  End of problem  The engine runs like a Diesel should.

      Thanks for all of the help!

                                                                                                                    Frank Mc cune