Sediment bowl or filter ?

[WPVT]

My 1954 218 flathead with a Carter BB has a glass bowl at the inlet side of the carburetor, what I've always called a sediment bowl. This one, by Carter, contains a filter element made of a white, porous pumice-like substance. Can these filters impede the flow of fuel ? It looks clean, but it may be the original. The glass bowl never fills up....it only has about 1/4" of fuel in the bottom. The truck runs OK. 

[JBNeal]

That stone is a filter, believe it or not, and the voids can gum up with varnish..take the stone out and soak it in lacquer thinner for a few days, rinse off with lacquer and repeat...typically that glass bowl should be almost full at idle, with occasional air bubbles forming when the fuel pump shifts out of bypass mode

[WPVT]

Thanks JB. I'll do that. I'd like to see that bowl a little more full. 

Once they put the filter element in, the bowl must have ceased to be a sediment bowl, since the sediment bowl idea relied on the fuel flow's decrease in velocity once it left the fuel line and entered the bowl. Have I got the physics right?

Edited August 30, 2020 by WPVT

[JBNeal]

The primary sediment bowl is on the fuel pump, whereas the filter bowl before the carburetor is a small reservoir for a standby fuel reserve when the hammer is dropped...so there are technically 4 fuel reservoirs on the truck:  carb, filter, pump, tank, with the filter and pump reserves on standby for such instances as starting from a stop with a full load and downshifting while climbing steep grades, allowing a smooth application of shaft power.  The filter bowl catches smaller contaminants from entering the carburetor by forcing the fuel through a filtering medium, as by this point the larger contaminants have fallen out of the fuel stream in the pump sediment bowl.

 

Depending on the filter body you have, there are 2 possible pleated fuel filter replacements available...the stone works fine when its clean, but they do degrade over time and can fall apart if they bounce off the shop floor when a case of the butterfingers hits.  I've used both and they work well

[Plymouthy Adams]

8 minutes ago, JBNeal said:

The primary sediment bowl is on the fuel pump, whereas the filter bowl before the carburetor is a small reservoir for a standby fuel reserve when the hammer is dropped...so there are technically 4 fuel reservoirs on the truck:  carb, filter, pump, tank, with the filter and pump reserves on standby for such instances as starting from a stop with a full load and downshifting while climbing steep grades, allowing a smooth application of shaft power.  The filter bowl catches smaller contaminants from entering the carburetor by forcing the fuel through a filtering medium, as by this point the larger contaminants have fallen out of the fuel stream in the pump sediment bowl.

 

Depending on the filter body you have, there are 2 possible pleated fuel filter replacements available...the stone works fine when its clean, but they do degrade over time and can fall apart if they bounce off the shop floor when a case of the butterfingers hits.  I've used both and they work well

I cannot see where the filter bowl at the input to the carb is a fuel supply for dropping the hammer...given no action from the pump...there is no manner the carb and extract from this reservoir...it is at best just another sight glass and final containment for heavy particles suspended in the fuel.  

[WPVT]

Thanks to you both. That is food for thought.

For now, I'll stick to my original query, and take the advice of cleaning the filter to see if that allows the bowl to fill better.

 

 

Edited August 30, 2020 by WPVT

[ggdad1951]

you can also buy small pleated filters you can replace as needed for the bowl.

[Los_Control]

I have the carter sediment bowl on mine .... it is always full to the top. My memory is fuzzy, seems like I use to have the pumice like stone, but do not have it now.

Mine also was something I added on, and came from a pile of spare parts. Thinking I just tossed it out and plan to buy the paper filter for it later.

 

What worries me about these cool looking sediment bowls, they are another source of a possible fire.  I have no experience with them ... Just the idea of them mounted above the exhaust manifold, the heat that occurs over time. The gasket getting hard and brittle.

I am thinking 2 years trouble free, then one day on the way to town it starts to drip .... A person really needs to be diligent about doing regular maintenance on them, make sure gasket is in proper condition and bowl does not rattle loose. And life is good.  (IMHO, with no actual experience)

 

To be honest, I am not sure I trust myself to stay on top of it. If I was building a trailer queen to take to shows, I would have to have it.

Building a daily  driver to splash through mud puddles, pretty sure I will remove mine, run a straight hard line to it. Just for peace of mind.

 

Besides filter maintenance maybe a proper gasket maintenance discussion would be valuable.

 

 

[dcotant]

Mine is always full too, unless I run out of gas it goes to about 1/3 full and is an easy way to tell there is something preventing fuel flow.

 

I have had my truck for over 40 years, daily driver for 20 years of that, never changed the gasket and did not remove bowl until recently and never had a leak. So i am less inclined to worry about it now.

[ggdad1951]

replace the seal if old and cracked and check in your maintenance schedule and you will be fine.  MANY, MANY old fuel systems used them.  Does not scare me.

[WPVT]

My guess, and it's only a guess, is that the age old sediment bowl design was at some point adapted by the Carter engineers to become a fuel filter by putting a ceramic element inside.

It would also be pretty easy for someone to turn it back into a sediment bowl if the element became an impediment. 

Later this week I'll give the element a good cleaning in solvent and report back as to whether that has an effect on the amount of fuel in the glass bowl. Then I'll have an answer to my own question of whether the glass bowl should be full when a clean filter element is in place, and the fuel pump is working properly. 

 

[JBNeal]

2 hours ago, Los_Control said:

...

What worries me about these cool looking sediment bowls, they are another source of a possible fire.  ...

The original setup, when properly maintained,  is fairly robust, and the fire risk is there but not as dangerous as ya might think...a dripping fuel bowl will mist during engine operation as the nearby cooling fan will disperse droplets, and the heat from the engine will flash off the volatiles...a severe leak will degrade engine performance, usually seen as stumbling at higher rpms as this reservoir level drops too low to be effective, and these performance drops would be significant enough to require attention.  I was taught to remove the sediment bowls every spring and scrub the crud outta the glass, as well as replace the filter and gasket as required...this coincided with cleaning the oil bath air filter and changing the crankcase oil and lubricating the chassis, distributor, generator, etc 

[WPVT]

I think I have the situation figured out, although the vehicle is 100 miles away at the moment.

 

With these ceramic element filters, the fuel enters at the top center, inside the element. The fuel passes through the element, fills the bowl, and exits through the top at the outside perimeter. What I am seeing must be the result of a clean looking, but totally clogged filter element. The fuel enters as explained above, can't pass through the element, so it pushes past a faulty gasket at the top, some of it runs down the sides of the bowl, and somehow enough makes it to the outlet at the top to run the engine. 

I have a new element on the way. Looking forward to seeing if it makes a difference in the engine at higher RPM's. 

[squirebill]

Has anyone had the fine mesh (brass?) screen at the top of this sediment bowl/filter disintegrate.  I'm guessing from ethanol.  I looked in the bottom of the sediment bowl at my fuel pump and saw what I thought was the mesh screen.  Thought it had fallen from the top somehow.  When I removed the glass bowl the sediment screen disintegrated to a fine powder in the glass bowl.  The vehicle had sat for quite awhile.   If I had been driving it regularly I guess the particles from the disintegration would have passed through the fuel system and not collected in the bottom of the glass bowl .  Anyone experienced this.  Do you have the screen at the top of the bowl or is it gone. Regards. 

[ggdad1951]

nope, but I use non oxy gas

 

gas should not "eat" brass....considering a few fittings in the fuel system are yellow metal, there would be more problems

[Plymouthy Adams]

this is the result of non being used and the resulting action of 'patina' ization 

Edited September 1, 2020 by Plymouthy Adams

[WPVT]

Following advice, I cleaned the ceramic element with lacquer thinner for 24 hours. The glass filter bowl now fills properly as one would expect. 

[Plymouthy Adams]

good deal, a little attention to details on these beasts goes a long way....