What Fuel Filters really do

[Ncostello]

After chatting with a Vice Pres at Stanadyne again, I was comparing their filters to the Fleetguards in terms of contaminant holding ability.



Just to make a long story short... most of our filters dont get clogged with dirt but rather with asphaltines... or little "tar" particles in the fuel. Thats why they often look black after several thousand miles. Eventually these particles build up a layer on the filter and restrict flow. There is really a low probability that actual "dirt" has entered a normal vehicle fuel stream.



Thus... these asphaltines present in all diesel fuel may play some role in the demise of Carter lift pumps. Which is another reason why I put a 30 Micron Fuel Water seperator before my lift pump then put a 5 micron unit after the pump.



Perhaps asphaltines build up in pumps and cause some problems we see especially with the motor bushings and electric parts.



Who knows what about asphaltines?

 

[Ron Bissett]

Better caught on the filter than on the injector pump or the injectors. You can't go wrong with added filtration to the system ,the bean counters would not add any thing that they can avoid and save a few $ . Thanks for the information ,seems like the Asphaltines are like the stuff the black top is made of. Ron Bissett in Metro Louisville KY

 

[illflem]

Originally posted by Ncostello





Who knows what about asphaltines?

There's no getting away from asphaltines, it's in all diesel fuel sometimes as high as 3%. It tends to settle out in slow moving parts of the fuel system but becomes completely soluble at 140°, which is not an unusually high fuel temp. It can be a problem settling in a stationary tank but rarely in a vehicle tank as the sloshing keeps it in suspension. The majority of asphaltine makes it though the fuel filters and burns, no problem. It would be impractical to try and remove it all.

I don't think it would affect a lift pump but there is nothing wrong with a prefilter except it may clog fast if the prefilter fuel is unheated in cold weather. That's one of the reasons the heater in our trucks is prefilter.

Additives have been experimented with to help dissolve asphaltines, but are caustic and damage the fuel system, the cure is worse than the disease.

It's something that diesel engines and filtration have dealt with since the beginning with success, I see no reason to get excited about it. Best bet is a fuel pressure gauge to monitor your filter and make sure your fuel heater is functioning in cold weather.

There are no asphaltines in biodiesel.

 

[Ncostello]

Thanks for the additional info Illflem. I'm not excited about it really... its just that I always pictured the filters stopping stuff that resembled dirt or grit particles... which of course they do just not as much as the asphaltines. If you take a "normal" contaminated filter and somehow get all the crud off of it... its mostly asphaltine particles. Thats what Stanadyne kinda hinted towards at least.



Since I have two filter heads... I put 150W heaters in lieu of the OEM 300W single heater. The heaters heat the fuel before it hits the filter material which leads me to believe I'm good to go.

 

[CumminsPuller]

Where is the heater located?



Jason

 

[Ncostello]

The heaters are intergal to the Stanadyne unit the same as the stock filter. The heater is a heat rod that installs from the top of the filter head. The rod goes down through the center of the filter. Thus fuel is heated as it travels into the filter head and down through the filter core.

 

[MCummings]

Maybe that's why a gasoline powered vehicle can go 50,000 miles before a fuel filter replacement?



Merrick Cummings Jr

 

[Ncostello]

I'd think maybe its because diesel has water, asphaltines (makes your filter black), and other gunk in it that gasoline inherently don't. The heater probably doesn't damage the filter in any way.

 

[illflem]

One member here reported going 62k on his stock filter before it finally plugged up. Most I've gone is 40k, I have a FP gauge, when it started heading down I knew it was time. Most of my fuel comes from my own tank though that has it's filter changed twice a year, it's never been extremly black.

I've run into four guys in the past few weeks whose filters have clogged with asphaltines, makes me wonder if the refiners have been skimping somewhere.

 

[Rman]

so leaving the filter in there, even when dirty, isn't necessarily a bad thing? I thought maybe the chance of letting particles get by might increase. I normally just stick with the 15k interval. I do carry a spare oil and fuel filter in my tool box just in case. What about air filters? I've yet to cean my mega cannon, i have about 17k on it. It's dirty but i'm reluctant to clean because it's supposed to last atleast 50k right?

 

[illflem]

The dirtier a filter is the better it filters, the dirt becomes filtering media.

That is until it gets to the point where it's filtering too good to meet the demand.

Trust the filter minder on your Cannon, I go 75-100k between servicing on my K&Ns.

 

[Rman]

roger that! I feel like i'm neglecting it but i guess that's why the minder is there.

 

[merryman]

Ncostello;



You have had your fuel pump/filter arrangement in for several months now. How about an update on how it has worked out and what you might do differently were you to do it again?



Vaughn

 

[Ncostello]

I am very happy with this setup after only 5000 miles. The Stanadyne filters are compact, high flowing, and are easy to change. They also offer excellent filtering capabilities. Even if I didn't move the lift pump and everything... I'd still consider installing a Stanadyne FM100 in place of the OE filter in its stock location.



I get consistent lift pump pressures. Always 15 at idle, in the 14's under most conditions, and sometimes into the 13's under heavy loads. Even after it drops down into the 13's its quick to recover back to the 14's even if your still applying the load.



I've noticed that at around 1/2 tank is my best pressures. I've cruised at 65mph before with 15. 5 psi on the gauge. But that only happens around 1/2 tank. Whether its full or 1/8 tank... my pressures are mostly consistent... although I tend to fill it up when I reach 1/4 tank.



I havent had any problems and dont expect any. Everything is working as it should. I can get to the filters easy, the pump seems happy, and if I ever need to change a pump it will take me no more than 15 minutes. Easy access is the key here.



It was alot of work... but it should have been somewhat like this from the factory anyway the way I see it.