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.

[John_Joey]

lane hog wrote:
..I also installed a $5 fuel shutoff about 3" from the carb inlet, so that hopefully it never sits wet again. Shut down the gennie after about 60 seconds of closing the valve....

Cheap and easy.... I like it!!!

[j-d]

Kit, from what I've read over the course of years the 4KY carb is tricky to clean. We had a certified ONAN tech here who said some of the passages have right angle turns in them and difficult to impossible to clear out. Kinda like the first time I worked on a Toyota carburetor. Could barely get the wire from a twist tie in some passages. I think I plucked a piece out of a wire brush. The Pontiac we had, I think I could about use coat hanger!

Carb replacement makes sense too, if you could get parts but had to pay shop labor for the tinkering. With new, there's a far better chance the thing'll run right. We pay, but get happier the better and longer it runs.

Consider doing what some of us do - fuel stabilizer treatment every tank. I know that on ours, it was a matter of weeks (OK maybe 8 or so) after a new carb that the genny wouldn't start again. I fought it on and off a couple years before replacing the carb.

For anybody interested, changing carb on 4KY is pretty easy with a couple odd tools, a couple tricks, and a good picture of how the linkage goes.

[Kit_Carson]

j-d wrote:
You ended up on the same path I took with an ONAN carb. I made several cleaning attempts and couldn't clear it up. Took it to a shop. You paid about half what I did, but I was as grateful as you are, and it took an ultrasonic cleaner to get it done. They called it a "rebuild" but that was years ago, when there were still some kits available. I could tell right away that the carb was better, but there was still a slight surge. Several steps down in the surge troubleshooting was "replace governor spring" and I decided to jump to that for $3 without all the other steps first. It did the trick.

GLAD you're enjoying a nice-running genny!

j-d, I just picked my MH up from the shop today. Generator would not start. The mechanic said he put a new carb on it. So far it is running fine. It was costly, but it is 8 years old and this is first problem I have had with it.

[j-d]

You ended up on the same path I took with an ONAN carb. I made several cleaning attempts and couldn't clear it up. Took it to a shop. You paid about half what I did, but I was as grateful as you are, and it took an ultrasonic cleaner to get it done. They called it a "rebuild" but that was years ago, when there were still some kits available. I could tell right away that the carb was better, but there was still a slight surge. Several steps down in the surge troubleshooting was "replace governor spring" and I decided to jump to that for $3 without all the other steps first. It did the trick.

GLAD you're enjoying a nice-running genny!

[MrWizard]

congratulations

[lane_hog]

Belated update...

The soak and ultrasonic clean worked. It's been running for a 60 minute and a 90 minute sprint today without any surging whatsoever. I might have been able to do a straight two hour test, but the fuel tank dropped below 1/4...

Freshly installed, the cleaned carb smoked like crazy for the first 10-15 minutes. Aside from that, entirely satisfactory.

I also installed a $5 fuel shutoff about 3" from the carb inlet, so that hopefully it never sits wet again. Shut down the gennie after about 60 seconds of closing the valve.

Word of advice... take pictures as you go should you ever try this yourself. It's really easy to lose track of what goes where...

[ol_Bombero-JC]

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

Acetone.

Never used it for same.

If those others don't ring your chimes....

give that acetone a try..:C

~

[MEXICOWANDERER]

X2 I like the ultrasonic part.

[westend]

Good call, that ought to clean it up nice.

[gotsmart]

John&Joey wrote:
MW, you are a plethora of sage advice ;).

....

Hush,
you'll mak is head esplode :W

[lane_hog]

I found a small engine shop nearby willing to do a three day soak and an ultrasonic cleaning for $30. Their main line of business seems to be varnish cleaning on yard trimmers, lawn mowers and snow blowers....

Figured that was a very reasonable price for their labor and materials, and cheaper than a gallon of Berrymans.... And, the acetone can be saved for doing adhesive cleanup which is what I'd purchased it for in the first place....

[MEXICOWANDERER]

A major part of the art of rebuilding is to use a rubber tipped air nozzle and plug it against all holes encountered then press the button. I can't possibly remember the number of times a tiny passage withstood 100 psi for a few moments then went ptui...hiss.

California does not top my list of states with a history of intelligent legislators or legislation with things that are the product of engineering. But that's no reason to stop a carb rebuild. Replacement of a viton needle and seat is vital. New Gaskets can be cut with a little patience and an exacto knife

Yeah mine the bauxite. Electrolysize the aluminum. Cast it in furnaces. Electricity - burn coal - petroleum for transportation. To a nitwit legislatot that is "greener" than a few cents worth of gasket paper, brass, and viton. Don't smirk - you elected them...

[Sam_Spade]

dougrainer wrote:
SEA Foam does not always get all 16 open and clear.

That is not too surprising, since it was created to be a marine fuel stabilizer and became a "fuel system cleaner" only because of marketing.

If one needs a carb cleaner, Berrymans B12 or Gumout are much better.

[dougrainer]

You do not have to pull an Onan Carb to fix clogged orifice jets. YES, orifice jet holes are clogged. Your symptoms are exactly what is caused by a gummed up carb. The reason Onan does not sell rebuild kits is because of our favorite state--California. 25 years ago California, had the most restrictive Emission laws, and Onan did and could not build Carbs that would meet California and the rest of the USA. So, Onan adopted the California standard which mandated sealed carbs. If you are careful you can remove the Carb Bowl, and then unscrew the Main jet. then soak in carb cleaner and blow it out. You can hold it up to the light and see if all 16 holes are open and clear. You then reinstall and you are good to go after making minor adjustments on the mixture main screw. SEA Foam does not always get all 16 open and clear. Doug