the air intake of the gasifier . (thought i should clarify that)… i suppose its from the smoke rising and condensing in the intake pipe … it only happens after i shut the system down… i do seal the pipe but when i open it (unscrew the cap) gooey tar runs out … yum… my intake is pretty high almost above the top of the hopper … I’m sure if it was lower the tar would burn off and this wouldn’t happen… not sure …
When you shut down the gasifier after a drive, the unit is still producing gas and will build up pressure. The gas will leak out the path of least resistance. I close off my intake air tight to keep the goo down to a minimum. I open a valve down stream in the heat exchanger or the filter to relive the pressure and the gas has no tar. You can also use shut down to find leaks.
You need to get Wayne’s book and build his system if you want better performance without getting tar in the engine. I spent years trying to get a full size truck to run good and got failure after failure costing thousands of dollars in materials and wasted time was even more. There is no reason you shouldn’t be able to run just like Chris’ truck.
Ha! Ha! Excellant advice Woody.
I’ve gone the same route of wasted time and money with damaged engines. Hooking up with Ben Peterson on for my small engine stuff let me coatails in on his years of developing. Fellas like him and Wayne have actually accumulated a mountain of tried, failed, burnt out or just not good enough ideas put into metal. To bad he has gone strictly proprietary commercial now.
System self-pressurizing is one of those thing not so far in any of the books or papers and been a way to separate out the actual on hands operators from the well read Posers or one time YouTube posters. Ha! Ha! Still a few of those touch points left that only someone either running for a dozen to a hundred+ hours will know from running themselves into these hurdle walls. Like soots accumulations, casting corrosions and so forth.
Chris Seanz touched on some of these farther up. And a very eagle eyed person with a few hours operations can pick up some of it in Why and Why Not a thousand hours operating guy like Wayne and a small handful of others do things a certain way. The first operator baby toutch point step is, “Where is all this condensate coming from??” when your gas flow chokes off from a condensate accumulation blockage.
Regards
Steve Unruh
its been a while since my last post … i have to work now 
can you tell … such is the life of someone in agriculture and raising two boys to boot takes most of my spare time ! all i can report is she’s still running … and i have a top speed of 68 mph … it was running really well with pretty darn good acceleration ! thats all … i haven’t put gasoline it it for … well over two months… wow!
I’m making a “wood dryer” which is a 12’ x 5’ deck with some glass cold frame panels fitted over it … I’m not done fixing the glass yet but it should get between 120 to 140 degrees f inside … ill put my chunks /chips in here to dry for a while … Cheers …
My first gasifier looked a lot like yours.i never got mine too run any thing ,so i bought the plans from WK and i am ever graitfull too wayne and group for saveing me much more time and money than any cost,The first flare was enough for me too know it works, Then i got the WK plans, If i had lots a money i might have spent all the time,14" cut off wheels. welding rod,electricity,co2,gasoline,finding steel.Your time wont be waisted though because your learning while building.The only thing i regret is not buying the plans sooner because this is all new learning for me,Caint wait too get my s10 running on wood with the 4.3 after i finish my 2500 wood hauling chevy truck.The obd 1 dakotas 318 are the easy’est set up over all with the timeing advace advantage,and miles per pound of wood,and good power on wood due too the big motor in small truck,and less cleaning problems with the intakes.The older trucks like we have will be easyer to pull the intake when engine stops breathing due to carbom buildup, not sure what the milege for clean out is, allso depending on feed stock variables.or wood fuel hitting the intake. The dakotas dont have too pull the intake for cleaning witch is exspained in the plans.Much more to learn than just a design, for most anybody just getting the learning curv learned, CAINT WAIT TOO FLARE MY WK IN A FEW WEEKS OR SO.I dont finace much so i caint comment on rubber hitting the ashfault.BBB