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-   -   Gummed up? (http://www.rcuniverse.com/forum/gas-engines-142/11441473-gummed-up.html)

pe reivers 03-12-2013 03:01 PM

Gummed up?
 
1 Attachment(s)
from my tool box, I thought I should share tis picture with you all:
It is a very common reason for gas engines not behaving like they should. Carbs not adjustable etc etc.
When cleaning a carb, look for gum like this. It will never wash off completely, unless you use the right detergents. I use a stiff brush and paint brush softener + compressed air. When I hold the screen up to a light, I can judge it's cleanliness.

STUKA BARRY 03-12-2013 03:37 PM

RE: Gummed up?
 
An inline filter in your gas jug and one after the pump will eliminate most of your problems.

3136 03-12-2013 09:33 PM

RE: Gummed up?
 
I run a felt clunk on my petrol can and a inline filter.
On all my planes they also have felt clunk in the tank and inline filter on the fuel fill line (3 line setup) and another filter on the carb feed line.
I haven't seen debris of any kind , but they still over time get gummed up.
Remove the mesh hold it to light and you'll see what P.E is talking about.
I have no idea what the buildup is but it clearly can pass through felt clunks and filters and gradually build up in the screen.

Hircflyer 03-13-2013 12:18 AM

RE: Gummed up?
 
I have read in several places its ok to remove this screen and just use an in line filter and a felt clunk in the tank.....anyone agree?

RCVFR 03-13-2013 03:50 AM

RE: Gummed up?
 

Quote:

ORIGINAL: Hircflyer

I have read in several places its ok to remove this screen and just use an in line filter and a felt clunk in the tank.....anyone agree?
People can write anything. There is no general requirement that one must actually know what they are talking about. But, apart from that, what possible advantage can there be in removing the screen? What is the upside to doing that?


skillet92 03-13-2013 03:58 AM

RE: Gummed up?
 
Quote:

ORIGINAL: Hircflyer

I have read in several places its ok to remove this screen and just use an in line filter and a felt clunk in the tank.....anyone agree?
I filter the gas going in the tank, and use a felt fuel clunk to filter the gas before the carb sees it and i still have to remove that screen on all my gassers atleast once a year to clean that kind of gunk. I would not remove it. That is stuff thst could end up in other parts of the carb thst are harder to clean.,

ahicks 03-13-2013 04:27 AM

RE: Gummed up?
 

Quote:

ORIGINAL: Hircflyer

I have read in several places its ok to remove this screen and just use an in line filter and a felt clunk in the tank.....anyone agree?

No.

BarracudaHockey 03-13-2013 05:29 AM

RE: Gummed up?
 
That screen is available in the Walboro rebuild kits, as pe said, its almost impossible to get fully cleaned.

Truckracer 03-13-2013 05:40 AM

RE: Gummed up?
 

Quote:

ORIGINAL: Hircflyer

I have read in several places its ok to remove this screen and just use an in line filter and a felt clunk in the tank.....anyone agree?
Absolutely not! That screen is the very last line of defense to keep crud out of the tiny drillings and fuel passages inside the carb body. If they get plugged it can be almost impossible to clean them out. The carb can then become a throw away item.


coralcape 03-13-2013 06:16 AM

RE: Gummed up?
 
Here is a method to clean your carb well. Remove the metering side cover and take out the pump needle,lever and spring. Put cover back on. Squirt carb cleaner into the fuel inlet line. then use compressed air in the fuel line to blow the carb clean. When you see the jets flowing, your good. Works for me. Good luck, red

Hircflyer 03-13-2013 11:48 AM

RE: Gummed up?
 
Thats why I was asking

pe reivers 03-13-2013 02:11 PM

RE: Gummed up?
 
The gunk in the screen is not some dirt particles that filters can arrest. It is a gummy deposit from the fuel, that clings to the surface of metal parts.
To clean the screen I use a stiff brush and brush softener, which dissolves the deposit.
Carb cleaning I do with an ultrasonic bath and my standard gasoline mix, after the carb has soaked in brush softener fluid. I guess that paintbrush softener is much like carb cleaner.
After the ultrasonic bath, I force rinse the carb using a syringe to the needle openings, rather than using compressed air. The syringe presses clean fuel trough all carb orifices, thus flushing away all debris loosened by the ultrasonic waves. The resulting amount of gunk and metal shavings and undefined debris found on the bottom of the tank after this procedure is truly amazing.
Much of it must have been due to carb assembly error. No way could all the coarse debris have passed the carb screen.

Hircflyer 03-13-2013 10:15 PM

RE: Gummed up?
 
Thanks thats the answer I was looking for....

Old Fart 03-14-2013 04:25 AM

RE: Gummed up?
 
The more filters you run the slower you finally choke the engine of fuel.Use a coffee filter to strain you petrol you won't believe the sh.. that you can see in the bottom.Then you can strip your carby once a year and clean it.

pe reivers 03-14-2013 04:54 AM

RE: Gummed up?
 
Only one filter is required in the plane. A felt clunk on the fuel pickup line. No restriction there, and it empties the tank right down to the last drop.

flygilmore 03-19-2013 10:46 AM

RE: Gummed up?
 
Also, its much quicker and easier (not to mention less chance to distort the shape of the screen itself) to just buy one from Walbro and replace it. No reason to clean with a brush and all that jazz. Done deal!

Bob Pastorello 03-19-2013 10:55 AM

RE: Gummed up?
 
Pe, as always, another great resource picture. That "gumming" occurs in any passage that fuel moves through, particularly bad in aluminum. The whitish-red gum/corrosion I *think* is just a byproduct of using crappy gas (assuming that nobody knows where or how to get "good" gas - I think it is a fictional compound theorized by carburetor and engine manufacturers to use as warranty-service disclaimer exclusion-clauses).

Cleaning carbs in an ultrasonic solvent-based bath has to be one of the best "carb maintenance" suggestions I've read in a long time, sir!!! Thank you!
(Ought to put this my sticky post at the top of the forum, if I knew how....)


Quote:

ORIGINAL: pe reivers

from my tool box, I thought I should share tis picture with you all:
It is a very common reason for gas engines not behaving like they should. Carbs not adjustable etc etc.
When cleaning a carb, look for gum like this. It will never wash off completely, unless you use the right detergents. I use a stiff brush and paint brush softener + compressed air. When I hold the screen up to a light, I can judge it's cleanliness.


MTK 03-19-2013 04:23 PM

RE: Gummed up?
 
That little screen seems like a good backing for a filtering element such as felt. When it gets clogged, toss it and replace. I haven't done it but I am curious how well it would work

Bob Pastorello 03-19-2013 05:28 PM

RE: Gummed up?
 
Matt, I've always wondered about gradual degradation of the felt clunks, permitting small pieces of it to migrate downstream to the carb. My "cure" of choice is the ceramic filter offerred by Madison Products (and others). It may not really be any better, but psychologically it gives me one thing less to worry about screwing up fuel systems.
Quote:

ORIGINAL: MTK

That little screen seems like a good backing for a filtering element such as felt. When it gets clogged, toss it and replace. I haven't done it but I am curious how well it would work

kerwin50 03-19-2013 05:36 PM

RE: Gummed up?
 
Thanks for the post Pe I'm now changing the screen on my carb.

pe reivers 03-20-2013 04:56 AM

RE: Gummed up?
 
Bob,
The felt does not degrade other than shrinking, and does not shed hairs. My clunks last for years. When I am working on a tank, the clunk gets a washing job, massage and good rinse. Good to go another year.

Bob Pastorello 03-20-2013 07:46 AM

RE: Gummed up?
 
Thanks for sharing your experience on the felt clunks. If I remember correctly, those are sold in a "Walbro" parts bag, aren't they?

Quote:

ORIGINAL: pe reivers

Bob,
The felt does not degrade other than shrinking, and does not shed hairs. My clunks last for years. When I am working on a tank, the clunk gets a washing job, massageand good rinse. Good to go another year.

pe reivers 03-20-2013 08:15 AM

RE: Gummed up?
 
I got a couple that were from Tillotsson; all the same stuff.

MTK 03-20-2013 08:18 AM

RE: Gummed up?
 

Quote:

ORIGINAL: Bob Pastorello

Matt, I've always wondered about gradual degradation of the felt clunks, permitting small pieces of it to migrate downstream to the carb. My "cure" of choice is the ceramic filter offerred by Madison Products (and others). It may not really be any better, but psychologically it gives me one thing less to worry about screwing up fuel systems.
Quote:

ORIGINAL: MTK

That little screen seems like a good backing for a filtering element such as felt. When it gets clogged, toss it and replace. I haven't done it but I am curious how well it would work

Bob,

Any felt material can be "treated" with a flame from a cigarette lighter. Briefly run a piece through the flame. Any loose fibers are remelted and drawn back into the body. Simple and effective (as long as gas is not present).

Talking felt, I have some teflon felt that will work great as a screen backer. No chance of degradation with teflon.I think I'll try it before saying too much more about it.

pe reivers 03-20-2013 12:58 PM

RE: Gummed up?
 
The fibres on the outside, which are curled up by the flame, are of no concern. It's the inside fibres that, if loose, can make it to the carb screen.
Having said that, I Never found loose fibers in my ultrasonic tank after soaking, massaging, cleaning, the felt clunks.
I have felt slippers. It is very hard to draw even one single fiber loose or break it. ( Fibrer = hair).
These worries are grossly overrated by repeated talks about it.
Truth is, :
these filters work.
They can be cleaned and restored to almost new shape, and then work, and work again!
They empty the tank to the last drop.
They effectively prevent fuel foam bubbles from entering the fuel line (gas AND glow) Ever watched your tank with running engine???
The clunk is a small fuel reserve for those impossible manouevres, so the engine won't starve.
The clunk has an incredibly low flow resistance.


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