Water Separator or also Fuel Filter Information

[Ski Bob]

Ok, I posted the much discussed fuel condensation in the fuel tank at the end of the season. So, now I am very interested in exactly WHAT the Water Separator actually does. Here is why I ask. I have owned my Four Winns 200 Horizon with a 4.3 Cobra for 22 years. I have been the mechanic on everything engine related. By the way, no major issues. But, my brother-in-law just purchased a used Sea Ray 210 with an Alpha 5.7 Mercruiser and I was nominated to winterize both boats. So, there were certainly differences. Now the issue.

When I removed the water separator from my 4.3 Cobra, it was about half full. I dumped it and tossed it and put on a new one. The separator for the Sea Ray was unscrewed and immediately sprayed water/gas? everywhere! I do not know how old either separator is. I forgot when I last replaced my Cobra one and being he just bought the Sea Ray, who knows.

Now, the bigger question. One guy told me that ANYTHING liquid in the separator was what was REMOVED from the fuel. Is this true? If so, the 4.3 Cobra filter had life left but the Sea Ray was full? In other words, what does this separator actually do?

I am familiar with an oil filter. It filters contaminates from the oil. In a car, the gas FILTER, filters contaminates from the fuel. So, how about a lesson on the Water Separator please? Is this an every season replacement as well? Thank you all for your professional advice.

 

[geneseo1911]

Re: Water Separator or also Fuel Filter Information

It's a filter and water separator rolled into one can. It should be more or less full of fuel. Normally, you dump it into a clear jar to see if it caught any water. The fuel flows in, is filtered, and any water, being heavier SHOULD settle into the open space in the bottom and stay there. Now, why was one one full and one under pressure...can't answer that. Likely having to do with amount of fuel in the tank, venting, plumbing, etc., etc.

I believe my manual says to replace it annually or 100 hrs. Probably overkill for a trailer boat, but they don't cost that much. I go biennially because I don't run that many hours, and buy all my gas from terrestrial gas stations, so the chances of water or dirt contamination are low.

 

[bigdirty]

Re: Water Separator or also Fuel Filter Information

....I am familiar with an oil filter. It filters contaminates from the oil. In a car, the gas FILTER, filters contaminates from the fuel. So, how about a lesson on the Water Separator please? Is this an every season replacement as well? Thank you all for your professional advice.

Well, you have pretty much said it there... :laugh: its designed to separate water/condensate from the fuel supply.. My personal opinion is yes, every year.. that said, i live in a climate that sees HUGE temperature changes season to season, and the more cycles up and down, the more chance you will get 'water' in your fuel system, auto or marine. I also drive a VW jetta diesel, and check (drain) my separator/filter regularly, and change it about every year, as diesel is even WORSE if the fuel gets contaminated with water.

Most gas engined cars will only have a fuel filter, as water isn't such a concern, but diesels being more prone to issues with water in the fuel (they do not tolerate much, let me tell you!) always have a water separator either as part of the fuel filter, like my little **** pot, or (in heavy duty/big rig motors) a separate "water separator" filter/unit.

BUT: Marine motors are ALWAYS around and in the water, and the chance of water getting into the fuel is much higher, so generally its a good idea to have a water sep. on the motor. It will bother a gas motor, although, its not the end of the world if there is water in the fuel; simply changing the filter and putting fresh fuel in is usually enough to fix the problem, unless the tank/lines are cracked/getting a lot of moisture into it.

The spray you say came out, I would say there was some residual pressure in the fuel system (EFI?) but if its just a spin on filter, my understanding has always been that the fuel will flow through it and it will trap/absorb any water or moisture before it can get to the engine. If the boat was running well, I'd just put a new filter on and fog/winterize it, fill the tank and put some fuel stabilizer in.

 

[icyveins]

Re: Water Separator or also Fuel Filter Information

just a quick note on the fuels that we have available to us are horrible with the effects of ethanol. The amount of ethanol in the fuels is increasing rapidly and getting worse everyday. spend the extra money on the green stabile for ethanol fuels. I do a lot of carb work on various engines and have noticed a lot more return customers because the way they store there fuels and engines is not up to snuff!
over a short period of time the water will separate causing major amount of GUM wherever there is fuel.
I have don't a small test on some of the gasoline we get around here.......
take a 20oz bottle and pour it about half full of gasoline and let it sit on a shelf in the garage for about two weeks and take a look at it once, if you have the results I have had you will be amazed at the amount of WATER that seperates in that short amount of time. let it sit for another two weeks and take another look......... its not good people and its only going to get worse..... just my .02

 

[jerryjerry05]

Re: Water Separator or also Fuel Filter Information

The things just a filter for dirt and a sediment bowl for water.
Remember the glass bowls on the older carbs?
It's to trap the uglies.
The 1/2 full filter is just the way it is bled or not.Nothing to worry about.
I installed clear filters on my outboards and 1 fills up and the doesn't???
Yes use the blue stuff for ethanol.
The stabil should be put in the tank on the last trip out.
Just putting it in at the winterization won't circulate it enough.
The amount of condensation a tank makes is small but enough to cause problems.
On my boat the water/sep filter hardly ever has water.
My trucks filter,yes!??
Icyveins said it it's only gonna get worse!!