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MTD 990 Twactor Guy
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Tore apart my carburetor off my MTD 990 B&S 16 hp single cylinder engine to clean and replace float, nozzle, needle valve, etc. Everything looked really nice and clean, until I removed the upper and lower carb bodies to get at the float. Yuck! White varnish cyrstals everywhere! Have you ever had this problem, and what cleaned it the best? I've tried the usual spray carb cleaners, tried acetone, and now I'm going to try some Seafoam.

Tell me your fixes and failures!

:thanku:
 

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Gumout or NAPA carb cleaner works for me. On real stubborn stuff, let it soak a few minutes. If really stubborn, spray, then scrape gently off with a really dull razor blade, then re-spray and wipe clean.
 

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AKA Moses Lawnagan
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Varsol....a lot cheaper than that other stuff...and it works.
And flammable as all heck. Don't even think about fire while you use it. A great industrial solvent, we used it to clean sheet steel and pipe in the welding shop I worked in as a teen. Cuts grease and varnishes better than most anything.

A spark from a guy welding landed in a small puddle of the stuff next to a 55 gallon drum of it, it was amazing how fast it went up. Long time ago, back before you had to keep those things in separate location from the work area to meet fire codes.
 

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Premium Member
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Make sure those white crystals of varnish aren't the aluminum body of the carb starting to corrode. When aluminum corrodes, it forms a white oxide, no saving it at that point.

I have had to learn that lesson the hard way.

Seth K. Pyle
 

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I have saved some really corroded zinc carbs that were all white inside on old cars no replacememt was available for readily,by using two things..
One is battery electrolyte..you can buy it at better auto parts stotres..

You fill a plastic bucket with it,deep enough to submerge the carb completely,after removing any brass parts like the float,needle valves,jets,etc..I tie a nylon zip tie to it for a "handle" so I can remove it easier,then leave it submerged for about 15 minutes,it will fizz like soda when you put it in the acid..after 15 minutes remove it,and rinse it off in a bucket of water with baking soda dissolved in it to neutralize the battery acid..flush it good with lots of water afterwards..it should be sparkling clean now,though some pitting may remain..

Another method I tried I read about in Hot Rod Magazine worked well to--you use a plastic bucket of water with Sani-Flush or Vanish toilet bowl cleaner,believe it or not!..same way as the battery acid,only you jusyt need water to rinse it off later..they warned not to leave it submerged TOO kong,or your carb COULD indeed "vanish"!..

For varnish ,Acetone or Laquer Thinner is hard to beat, but is pretty expensive and can be hazardous due to its voltility..Denatured Alcohol eats away pretty much anything if you soak it in it long enough..

I like Chevron "Techron" for adding to gas tanks ,I haven't tried Seafoam yet,I have heard both good and not so good results from others who have used it..(nothing "bad",some just felt it did nothing,no good or harm,and considered it a waste of money)..
 

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MAny motorcycle shops have a 'dip bucket' for carbs. Might try locating a dealer with one.......if all else fails.

The stuff in it smells like creosote(sp?)
 

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ROJ
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when im in a hurry to use the carb so there is not time to soak it i tear the carb completely apart at the work bench using lots of gumout carb cleaner and a bread wire tie to clean each small orifice,the ones that are too small for a bread wire tie to go thru,i take a strand from a piece of small gauge electric wire and very carefully use it.
 

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I do much the same too--I pluck a bristle out of a wire brush ,and use copper wire too,which is unlikely to hog out the holes in the jets..sometimes I use torch tip cleaners if I have them handy too,but those can enlarge holes easy if your careless or use one too big!..stiffer wire is a lot easier to use than soft stuff like a bread tie..(but pokes your fingers easier too!)..

I find blowing carbs out with air is OK,the higher the pressure the beter--but on Tecumseh carbs I've blown that seat for the needlve valve into iblivion a few times,its best to apply air from the needle valve side only on those!...
 

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Super Duper Member
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I do much the same too--I pluck a bristle out of a wire brush ,and use copper wire too,which is unlikely to hog out the holes in the jets..sometimes I use torch tip cleaners if I have them handy too,but those can enlarge holes easy if your careless or use one too big!..stiffer wire is a lot easier to use than soft stuff like a bread tie..(but pokes your fingers easier too!)..

I find blowing carbs out with air is OK,the higher the pressure the beter--but on Tecumseh carbs I've blown that seat for the needlve valve into iblivion a few times,its best to apply air from the needle valve side only on those!...
I do the same exact thing when cleaning out old carbs. I could not clean the original carb off of my 318 to save my life. I tried wires, tip cleaners, had a local shop soak it for days. The tractor kept on surging, no matter how many times I cleaned it, and blew air through it. Also, the carb on a 318 has a little freeze plug looking cap that will blow out if you use to much air pressure on it.
 

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:bannana: Hands down, an ultrasonic cleaner is the best “tool” on the market for cleaning carburetors safely, and without damage to the carburetor.

I have saved several carburetors, both two and four cycle, from the scrap pile with my unit. A good quality unit along with the right combination of temperature and cleaning solution is the key.

Oh, and most important step most people ignore. COMPLETE DISASSEMBLY OF THE CARBURETOR!

No ridiculous soaks and or loud chemical odor, well almost.

Down side is the initial cost, however, mine has paid for itself.

White varnish cyrstals everywhere! Have you ever had this problem
Yes, the white death, once the manufactures coating has been breached, it really doesn’t matter what you do, it will simply progress. If in fact that is what it is. Good luck.:trink40:
 

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AKA Moses Lawnagan
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4,642 Posts
Something we radio control airplane guys use to clean our glow engines, is an old Crock-Pot that has the ceramic removable tub. Fill it with antifreeze that is compatible with aluminum, disassemble the carb and put it in the crockpot on low overnight.
You can drop an entire glow engine into this solution, and it will come out looking brand new. The ethylene glycol dissolves the varnish deposits that the burnt methanol, nitromethane and castor oil fuel leaves on the engine, and doesn't harm the metal at all. Most glow engines are aluminum castings with either brass plain bearings or steel ball bearings, it doesn't hurt any of the metals.
 
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