Soaking Onan Carb in Acetone?

[lane_hog]

Assuming I do a tear down and remove the seals/plastics, has anyone had good or bad experiences with small engine carbs and acetone?

I've got what I suspect is a gummed carb on my Onan 4K, after it had an unexpected time out where I couldn't exercise the gen monthly and didn't have an opportunity to drain the bowl.

The gen runs, but surges under a load and dies usually after 20-30 minutes. I've tested the fuel pump and filter, and both seem to be fine, so I'm moving on to pulling the carb and doing a soak.

[westend]

I have a gallon of carburetor cleaner with a basket inside it. It dissolves most things within a few hours, including plastics and rubber. It is the most vile smelling stuff I've come across but it works. IIRC, it was cheaper to purchase than a couple of pints of acetone at today's prices.

Some issues I've had with cleaning carburetors is that the undissolved blockage in main jets or orifices may be hard mineral (AKA, that piece of sand that gets transferred between fuel storage tank and equipment fuel system). I can see where an ultrasonic cleaner would shine in that case.

[Jframpey]

Acetone is an aggressive solvent, any plastic will swell. I used acetone to soak a paint spray gun and ruined it... There was a bushing in the needle shaft that swelled to the point where I couldn't get the needle back in! If there's any plastic in the throttle shaft housing - look out!

Use solvents specifically designed for carbs.

[j-d]

nineoaks2004 wrote:
do not use acetone unless you want to buy a new carb, there is a coating and acetone will remove it"

Hmmm... I know that in automotive, there's "Carburetor and Choke Cleaner" and then there's "Throttle Body Cleaner." I'm told Throttle Bodies have a coated throat, the air flow area, that has a special (guess what?) COATING that C&C Cleaner will remove but TB Cleaner won't.

I was ready to reply as above: You've got Acetone, you want to try it, so try it. Now I wonder, thinking of Coatings.

I can tell you we had an older ONAN carb that was plugged. I've tinkered small engines for years and I'm pretty good at carburetors. Finally sent this one out to a shop that could clean ultrasonically. They got it running right after I tore it down several times and couldn't.

[nineoaks2004]

I just checked with my son who works in a large small engine shop, "do not use acetone unless you want to buy a new carb, there is a coating and acetone will remove it" either get it ultrasonically cleaned (best) or soak it in gasoline (next best)...

[John_Joey]

What you said made sense, give it a try. Just watch out for the flash point of acetone, but you knew that already. Only thing I would watch out for is any plastic parts (i.e. float, float pin) that could dissolve. Those parts I would not soak that's for sure.

Your 13 years of Onan internet carb reading reminds me of an old TV French model commercial though. :B

[lane_hog]

Onan carbs have some specific attributes which differentiate them from other generators, so solutions which work for a "normal" small engine don't necessarily work.

Specifically, the jets are not removable, and the interior passages are too small to probe and also have 90* bends in them.

Cummins sees these carbs as a consumable, and won't service them.

Based on 13 years of reading postings from other Onan owners with similar issues, the carbs do not respond to Seafoam or sprays.


Running Seafoam in the gas is a good option if the carb isn't blocked, but can't do anything if it can't even get to the blockage. There's no suction to pull it into the passage.

Same thing with spray cleaner -- it can't force its way into a dead end.

An extended soaking (24 hours with some agitation) seems to be the only way for solvent to get to the blockage.


THAT's why I am asking specifically about a solvent for soaking.

Sam, I know that soaking might not work, but I'd rather try using some acetone (that I already own for clean-up), versus dropping $160 on a new carb....



A few people others suggested B12 Chemtool carb cleaner.

B12 is 50% toluene and 25% acetone.

If you think acetone is dangerous, read the sheets on toluene...

Maybe the two combined together are somehow safer?...


After 13 years of reading these forums, and seeing dozens of others posting similar issues, I'm not going to expect solutions which haven't worked for others to suddenly start working here.

If you find that offensive, my apologies.

[darsben1]

lane hog wrote:
Guys, I asked about Acetone. Not carb cleaner or Seafoam... 😉

I am sorry.
I will change my answer
DO not use acetone due to its potential side effect.

ACETONE MSDS

Why don't you try Seafoam mixed in a gallon of gas. Connect gas line to the gallon and let her rip.
That should clean up the carb.

Hope that is better

[harold1946]

lane hog wrote:
Assuming I do a tear down and remove the seals/plastics, has anyone had good or bad experiences with small engine carbs and acetone?

I've got what I suspect is a gummed carb on my Onan 4K, after it had an unexpected time out where I couldn't exercise the gen monthly and didn't have an opportunity to drain the bowl.

The gen runs, but surges under a load and dies usually after 20-30 minutes. I've tested the fuel pump and filter, and both seem to be fine, so I'm moving on to pulling the carb and doing a soak.

Onan has a product called "4C". it is an engine an carb cleaner.
There are many instruction videos on all the various carbs on youtube.

[nineoaks2004]

I work on quite a few small engines and I purchased an ultrasonic cleaner from Harbor freight,with a heater built in the only thing I use in it is water, dawn dish liquid and a few drops of ammonia, the carbs come out like new. You might check with a small engine shop and see if they can "cook it for you"

[Gdetrailer]

lane hog wrote:

Sam Spade wrote:

lane hog wrote:
Guys, I asked about Acetone. Not carb cleaner or Seafoam... 😉

And the answer, from several people, is:
NO, do not use acetone.

That's not what the answer has been. I get that a lot of people like Seafoam.

I'm asking if anyone has tried acetone (which is one of the main components in B12).

The answer is still NO, NO to acetone by it's self.

Clearly you do not understand just how to clean a carb.

The problem you have is THE MAIN JET has gotten clogged.

In most small engine carbs the main jet is accessed by removing the carb bowl.. The jet is typically housed in the little stem that the carb bowl screw goes into.

Most main jets can be removed via a flat blade screw driver.

You remove the jet, and using a SPRAY CAN of CARB CLEANER you FORCE the built up junk out of the jet..

No soaking needed and if you do it correctly you do not need to remove the carb..

Not to mention straight acetone is highly flammable, evaporates almost instantly which makes it an extremely POOR CHOICE to use as a soaking liquid.

You would have to have a completely air tight container in order to be able to use acetone.. Just not worth the hassle, there ARE better ways to clean a carb.

[lane_hog]

Sam Spade wrote:

lane hog wrote:
Guys, I asked about Acetone. Not carb cleaner or Seafoam... 😉

And the answer, from several people, is:
NO, do not use acetone.

That's not what the answer has been. I get that a lot of people like Seafoam.

I'm asking if anyone has tried acetone (which is one of the main components in B12).

[Sam_Spade]

darsben1 wrote:
Why don't you try Seafoam mixed in a gallon of gas.

Seafoam is a marine fuel stabilizer.
As a carb cleaner, it is overpriced snake oil.

Berryman's B12 Chemtool or Gumout are much better.

[lane_hog]

Toddupton wrote:

lane hog wrote:
Guys, I asked about Acetone. Not carb cleaner or Seafoam... 😉

Wow! Really?

Yes, really. I know the norm on forums is to ignore the original question, but I thought I asked a fairly targeted question. But, happy to restate if it wasn't clear enough...

I'm already planning to doing a tear down -- it's a ten year old carb, and I know there's going to be gunk inside. If it's off the block, the tear down will be followed by a soak.

I'm looking for advice on what to soak it in, not for what additive to put in the fuel, or how to clean it while it's running.

[Sam_Spade]

lane hog wrote:
I've tested the fuel pump and filter, and both seem to be fine, so I'm moving on to pulling the carb and doing a soak.

Totally unnecessary to do all that work.....probably.

Get some Berryman's B12 Chemtool. It is made to be a carb cleaner.

Given the tests that you have already done, you should be able to get a healthy dose of that into the carb while on the machine to soak right there.

A 50/50 mix with gas fed into the fuel pump intake until it stumbles a little should do the trick.

Let it sit overnight and then run it normally for a bit to see if it is better. If it IS, put a recommended dose of B12 in the regular gas supply and pray.

When I got mine it had been neglected so bad that two attempts at professional cleaning failed and it required a new carb; about $250 installed at a Cummins dealer. I enjoyed screwing with things like that when I was younger; NO MORE. It's been running like a top with it's new carb. Well worth the money.

[raross61]

I would highly suggest you have the carburetor ultrasonically cleaned, almost all the newer small carbs have a coating on them! Almost all shops have one for these smaller carbs, and they work great! BoB