Aftermarket In-Line Fuel Filter = Engine Damage

[TWFisher]

I was recently discouraged from using an aftermarket in-line fuel filter because, "Those filters will cause fuel/oil separation resulting in major engine damage".

So I thought I'd check around with the iboats group before instaling one.

Anyone ever had an issue?

 

[ddrieck]

Re: Aftermarket In-Line Fuel Filter = Engine Damage

I run a Purilator in line filter, the glass see through type with removable and cleanable screen. I have been using this type, not the same one, filter since the early 80's and have never had an issue or failre due to oil/fuel separation

Darren.

 

[Mark42]

Re: Aftermarket In-Line Fuel Filter = Engine Damage

If you check with the manufacturers of the filters, you will see that the name brands all state that the filters will not separate gas from oil.

Seeing as both gas and oil molicules are under 10 microns, they both pass through the common 10 micron filter. Water being larger than 10 microns, does not pass.

 

[45Auto]

Re: Aftermarket In-Line Fuel Filter = Engine Damage

Ran an aftermarket see-through in-line filter on my 120 Force running 40:1 premix for 7 years. It was still running like new when I sold it to get a bigger boat.

 

[Span 24]

Re: Aftermarket In-Line Fuel Filter = Engine Damage

If you check with the manufacturers of the filters, you will see that the name brands all state that the filters will not separate gas from oil.

Seeing as both gas and oil molicules are under 10 microns, they both pass through the common 10 micron filter. Water being larger than 10 microns, does not pass.

See! I like the Science in this answer. Not much else to say eh?

Michael

 

[Mark42]

Re: Aftermarket In-Line Fuel Filter = Engine Damage

If you check with the manufacturers of the filters, you will see that the name brands all state that the filters will not separate gas from oil.

Seeing as both gas and oil molicules are under 10 microns, they both pass through the common 10 micron filter. Water being larger than 10 microns, does not pass.

Actually, I do believe water is under 10 microns. But there is a lot of physics involved with how water molecules bond and what happens with alcohol in the mix, and dirt, etc.

If you notice, most filters advertise something to the effect of "filters out contaminants larger than 10 microns and separates water..." . The $64000 question is how does it separate water?

I have tried to find something that explains exactly why water won't pass a 10 micron filter in fuel, but passes through a 10 micron filter in my house!

I don't think the filters are simply absorbing and holding onto the water like a paper towel, otherwise there would be no need for a water drain at the bottom of the filters with a water sight bowl.

Maybe some chemists can add their two cents.

 

[This_lil_fishy]

Re: Aftermarket In-Line Fuel Filter = Engine Damage

Actually, I do believe water is under 10 microns. But there is a lot of physics involved with how water molecules bond and what happens with alcohol in the mix, and dirt, etc.

If you notice, most filters advertise something to the effect of "filters out contaminants larger than 10 microns and separates water..." . The $64000 question is how does it separate water?

I have tried to find something that explains exactly why water won't pass a 10 micron filter in fuel, but passes through a 10 micron filter in my house!

I don't think the filters are simply absorbing and holding onto the water like a paper towel, otherwise there would be no need for a water drain at the bottom of the filters with a water sight bowl.

Maybe some chemists can add their two cents.

More a physics queston maybe. However a very good point, heck a tap filter can run as low as 2 microns if memory serves. So if water is more then 10 microns that would be a mighty dry tap.

Ian

 

[n2ostroker]

Re: Aftermarket In-Line Fuel Filter = Engine Damage

I run my old 50hp Rude with 2 inline. I've ran it this way for 10yrs since I've owned the boat. I use the cheapy metal inlines.

 

[Vex]

Re: Aftermarket In-Line Fuel Filter = Engine Damage

If I am thinking of the same filters you are describing water passes right through them. Water is heavier than gas and thus sinks to the bottom of the filter/bowl where it is drained out the bottom of the bowl before it gets to your engine.

 

[The_Kid]

Re: Aftermarket In-Line Fuel Filter = Engine Damage

Actually, I do believe water is under 10 microns. But there is a lot of physics involved with how water molecules bond and what happens with alcohol in the mix, and dirt, etc.

If you notice, most filters advertise something to the effect of "filters out contaminants larger than 10 microns and separates water..." . The $64000 question is how does it separate water?

I have tried to find something that explains exactly why water won't pass a 10 micron filter in fuel, but passes through a 10 micron filter in my house!

I don't think the filters are simply absorbing and holding onto the water like a paper towel, otherwise there would be no need for a water drain at the bottom of the filters with a water sight bowl.

Maybe some chemists can add their two cents.

I'm not a chemist, or any other type of scientist, but I'll give it a shot. Yes, a water molecule is smaller than 10 microns, but so is a gas molecule. A water molecule measures 0.278 nm and one micron is 1000 nm (nanometers) in size.

Filters/separators work based on the specific gravity of water being heavier than gas, and the surface tension of water, being almost 4 times greater than that of gas. In the separator the lower surface tension of the gas allows it to flow through the filter a lot easier. The higher surface tension of water prevents it from going through as easily. The water that is blocked sinks to the bottom since it's heavier.

Water will pass through a 10 micron fuel filter, just as it passes through a 10 micron filter in your house. When the water level in the fuel filter gets high enough to where the the pressure from the fuel pump overcomes the surface tension of the water, it will pass through the filter.

 

[Mark42]

Re: Aftermarket In-Line Fuel Filter = Engine Damage

I'm not a chemist, or any other type of scientist, but I'll give it a shot. Yes, a water molecule is smaller than 10 microns, but so is a gas molecule. A water molecule measures 0.278 nm and one micron is 1000 nm (nanometers) in size.

Filters/separators work based on the specific gravity of water being heavier than gas, and the surface tension of water, being almost 4 times greater than that of gas. In the separator the lower surface tension of the gas allows it to flow through the filter a lot easier. The higher surface tension of water prevents it from going through as easily. The water that is blocked sinks to the bottom since it's heavier.

Water will pass through a 10 micron fuel filter, just as it passes through a 10 micron filter in your house. When the water level in the fuel filter gets high enough to where the the pressure from the fuel pump overcomes the surface tension of the water, it will pass through the filter.

I think you and VEX are right on the money. The tests done by Continouswave.com showed:

None of the filters tested will stop water from entering your engine once the canister is full...

So surface tension and gravity get my vote for how the filters block water.

Here is the report if anyone is interested: http://continuouswave.com/whaler/reference/fuelFilter.pdf It's worth saving in your favorites.

 

[TWFisher]

Re: Aftermarket In-Line Fuel Filter = Engine Damage

Ok, so, is there is a molecular bond between the gas and oil? I was wandering why the solution would not settle out over time, with different SG, oil on bottom, gas on top, but if there is a molecular bond then this would not happen. I've been wandering about this.

I work with a chemical engineer, I'll see what his thoughts are about this. Ill copy his reply.

But still is it possible for a filter to break this bond and cause seperation?

The guy who told me about this swears this will cause a hot spot on the piston and failure.

 

[capt sam]

Re: Aftermarket In-Line Fuel Filter = Engine Damage

you cannot compress water, you'll get hydrolock but the motor will die before that from lack of combustion.

 

[Frank Acampora]

Re: Aftermarket In-Line Fuel Filter = Engine Damage

Running a filter beats the heck out of clogging a carb inlet and melting a piston due to lean-run detonation.

Fuel and oil are completely soluable in each other and as such will pass through any fuel filter as a mixture. At the carb, the fuel will vaporise while the oil with a much higher vapor pressure will form droplets which pass through the engine, lubricating it.

 

[jay_merrill]

Re: Aftermarket In-Line Fuel Filter = Engine Damage

If I am thinking of the same filters you are describing water passes right through them. Water is heavier than gas and thus sinks to the bottom of the filter/bowl where it is drained out the bottom of the bowl before it gets to your engine.

I believe that this is the correct answer. Water separator/filters do not "filter" the water out, they allow it to sink to the bottom of the canister. In-line type, mesh filters don't filter water or oil - they filter particles.

I use both a water separator/filter and an inline, wire basket type filter. I've never had any engine problems as a result.

 

[tashasdaddy]

Re: Aftermarket In-Line Fuel Filter = Engine Damage

if running a built in tank, a fuel/water separator is a must have. imho.

 

[Mark42]

Re: Aftermarket In-Line Fuel Filter = Engine Damage

Some tractors and motorcycles I've owned had glass site bowls or steel bowls on the petcock without an integrated filter. Gravity was all that it took to make the water settle to the bottom of the bowl. The motorcycles had the most collection of water and grit in their bowls.

Gravity is a good thing.