i picked up a set of dynomax shorties off ebay a few months back & was pretty shocked when i got em...of course none of the issues were listed nor were they pictured.talking to the seller it seemed i was picking up a decent set that needed the a.i.r. ports welded shut & some hi temp sprayed on.

so when it came time to prep em i noticed some serious blockage that halted everything.i assumed when i got em they were in a shed for a while due to the dirt & cement inside along with the spiders & such.this dude claimed they came right off a running car he junked,which in short order came apparent that was complete bs.

so far ive cleared all but one tube...ive never seen anything like this.the carban/oil gunk deposit that was solidified in there was a few inches thick & wasnt were any kind of brush could reach,and i tried many.
heres what ive attempted so far in clearing this crap out:

brakekleen
carb cleaner
oven cleaner
drano
propane torch
paint stripper/thinner
gas
lighter fluid
and just about everything else that should be corrosive enough to melt it out.so any thoughts on other chemicals/methods?
i just wonder how that guys car even ran or got that bad on just that one cylinder

 

his car must have had a really bad leaky valve and thats all burnt oil and crud.

its going to be quite hard to get all that crap to breakup. You be better of trying to chisel is out, or take the loss and get a different set of headers. Thats the chance you take on used parts.

 

with the time i spent dropping the extra change in the first place,ive been trying to chisel it out with no luck.i'm gonna see if my neighbors sand blaster might do the yrick

 

I've seen some serious crud @ our Rad Shop from burnt Compressor Oil and blah blah
Try to soak the tube, if you can block one end
The stuff we use is Lacquer Thinner
Both we use need very heavy ventilation, so don't use in a Garage
The first kind has a flash point of about 11c and is good for wiping down stuff prior to painting
The nasty stuff you may need has a flash point of -7c
Yes, I said 7c Below
You can't put this stuff out if you prayed
Don't use it indoors or near any heat
We buy it from Cloverdale Paints but we could get it from General Paints, so I would assume you could get it from any local Home paint shop but I'm not talking about Lowe's something or other.
A specialty paint shop
You'll need to block one end with something that won't melt and fill it with the nasty stuff. Let it soak for a few hours and just dump it out
Stuff is amazingly strong

 

yea i gotta keep the fun stuff outside lol my neighbors would have me evicted.i live in a 4 family house & its old so fumes travel easy,about the only thing i do inside is paint but even thats risky cause the lp gas system.
i put a snake light in the tube to see what kinda gremlins where lurking about & the plug is literally solid.no light gets thru & to make maters worse its dead center.off the top of my head i think its the #4 chamber.so really soaking is all ive been doing,and ive used some brutal stuff.i mean the oven cleaner was that ultra potent $1 store junk that should eat anything.
is there a brand name that goes w/ that thinner you use?ive tried several but its all been walmart or home depot crap like you said.there's a few jobbers around here so i'm sure i can get that insane stuff you are talking about.that flash point sounds sound scary lol,so thats 14 & 44f respectively.i wonder why a company wouldnt try to improve on that,sounds like a ht slice of pizza would get that stuff burning lol.do you think a sand/media blaster might do a better job?that is the only thing i havent tried since i dont own one.but hey that gives me a excuse to get one finally...if that ends up being the routei take any suggestions as to what sort of media would work best?the walls are pretty nice but i'm sure enough blasting with the wrong stuff would weaken them in short order

 

We use a media blaster when we prep parts for Rad Recoring
I would not let you put that anywhere near our blaster, it will gum up our gun!
You also would not want someone to try to blast it all out as it will mess up your exhaust airflow
Try your best to chip /scrape/poke it all out and then get an engine rebuilder to hot-tank it. Rad shop hot tanks only remove light stuff. Engine builders use a much stronger mix of our same Sodium Hydroxide
As for your question about the nasty thinner, all I could give you is the # from Cloverdale Paints. 78017-05 is the #, but I doubt it will help you.
It's an 18.9L pail/bucket
Please, if you do find this stuff, be very careful with it
Besides the fact that it will burn your skin and remove paint, you could really hurt yourself/cause a REALLY big fire

When I first bought it, I showed the guys @ our shop how flammable it is...
I lit a shop rag soaked in it and tried to put it out with our flush gun....full city water pressure from a 1" pipe and full compressor pressure @120PSI.
Needless to say, we watched that shop rag burn to a crisp

Ok, I need to say it one more time.......

Don't screw around with this stuff, it's VERY DANGEROUS

Good luck

 

those good dip tanks are illegal to use in this state,the tech school i went to used to have one but when the law went in they had to get rid of it,which sucks because that was a BIG tank.about all you can find is the weak stuff pretty much now.believe me i'll take your warning,ive had lotsa stupid accidents over the years.way more than enough to know when i cant screw around,but thanks for the tip on that stuff.would you say that stuff is close to the volatility of ether?
well if the stuff is cost effective & i can use it for some other stuff i may get it.i'll try the local jobber & see if maybe i can get a small amount or something similar.

 

btw ,when you say gum up do you mean because you use a reclaimer?

 

The stuff we use is still legal in Canada. It's known as Caustic Soda
Check a local Engine Builder and ask them if they use it
It's called Sodium Hydroxode

I couldn't tell you about the difference between it and Ether

We pay about $100/18.5L Pail

 

Yes, we do use a reclaimer system
Good Eye dude
We never put anything wet/sticky/gummy/oily or what have you into our blaster

 

yea that would be a real pain in the a** to get out of the system.if i had room for a cabinet one i would get one but i think i'm limited to the spray & waste type.now that you mention it...it was a caustic soda that the school had thats illegal now..the best that can be done here is a hot tank with mild chemicals if any.the area where i live use to be all brass factories & they dumped that+all kinds of nasty stuff wherever they wanted so instead of stricter regulations on use they outright banned it.last time i checked chroming isnt done here anymore either,unless there is a cleaner method
to give you a idea of what was done:
http://en.wikipedia.org/wiki/Waterbury,_Connecticut
http://en.wikipedia.org/wiki/Naugatuck_River
back in the 50's & 60's the water was literally so toxic it was bright green & would bubble from what my mom told me.

 

Trying not to get off topic here...
Engine builders use some nasty chemicals to clean parts

 

gotcha...i ramble alot.yea they use some nasty stuff.sounds like the fed laws up there might be a bit more lax.but i really dont know much about the regs there

well i managed to get what seems to be a opening using liquid plumber,flows thru a bit easy so i got it set up where it pools up in the tube.maybe in a week they will be flushed finally

 

As a chemist I can say most chemicals that dissolve carbon residue are nasty (poisonous and flammable and clear). I'm pretty surprised that paint thinner, carb cleaner and lacquer thinner didn't dent this residue. I'd say try soaking or pouring straight into the tubes methlyene chloride Cl2C2H2. One of the most powerful way to burn off carbon based residue, but normally to prepare ultra-clean surfaces on glass is a mixture called Pirhana Solution. It is (I think) equal parts hydrogen peroxide (not the 3% drug store type, try 30%) and sulfuric aid mixed together. Careful using it though, as it oxides carbon compounds it can heat up.

 

believe me i'm surprised,ive never had this bad of a problem removing anything.the best way i can describe this crap is oil & carbon solidified into tire gunk like consistency from doing a nice burnout.ive never come across something that tough.the drano is slowly working now so hopefully this will do it.
so with that piranha solution,best bet would be to add small amount to avoid a flash?