360 Express 10 micron filters

[Texoma]

I have a 2005 360 Express with triple f250s. To other 360 owners w/triple 250s: How many full sized 10 micron fuel/water separator filters do you have? I ask this question because mine only has two full size and one half size (on the the port motor). The reason it has a half size filter on the port motor is because the bracket that the filter attaches to is placed too low to get a full sizes filter in. It would be a relatively easy mod to raised the filter bracket to the correct hight. I just wanted to check with other 360 owners if this was standard (2 full size & 1 half size) or a poor initial installation at the factory.

Thanks....

 

[seasick]

I have a 2005 360 Express with triple f250s. To other 360 owners w/triple 250s: How many full sized 10 micron fuel/water separator filters do you have? I ask this question because mine only has two full size and one half size (on the the port motor). The reason it has a half size filter on the port motor is because the bracket that the filter attaches to is placed too low to get a full sizes filter in. It would be a relatively easy mod to raised the filter bracket to the correct hight. I just wanted to check with other 360 owners if this was standard (2 full size & 1 half size) or a poor initial installation at the factory.

Thanks....

The issue is not filter size, it is maximum fuel flow rate. As long as the flow rate is greater than the demand, all is OK. Calculating the actual flow rate is not a simple task. You start with the flow rate of the filter ( often in the area of 90 GPH more than sufficient) and then subtract for fuel fittings, line size, line length etc.

The bottom line is that the filter size does not have a direct bearing on flow rate. So if all seems OK, don't go looking for problems, there may not be any. Other than the need to carry two different sized spares, there is probably no other issue.

 

[Tucker]

As usual, seasick is spot on. Only thing I can add is an opinion. It seems like these big 4-strokes are not exempt from the effects of dirty fuel. Also seems the ill effects of ethanol laced gas is really rearing it's ugly head like crazy this season. Based on what I've heard, if you get bit with this you better have a lot of room on your credit card, especially with triples. I'd pipe in another filter and change them over to 2-micron's. But, that's just MHO.

 

[fishingFINattic]

The issue is not filter size, it is maximum fuel flow rate. As long as the flow rate is greater than the demand, all is OK. Calculating the actual flow rate is not a simple task. You start with the flow rate of the filter ( often in the area of 90 GPH more than sufficient) and then subtract for fuel fittings, line size, line length etc.

The bottom line is that the filter size does not have a direct bearing on flow rate. So if all seems OK, don't go looking for problems, there may not be any. Other than the need to carry two different sized spares, there is probably no other issue.

I am sorry but there is some bad info here so let me go thru this post.

"As long as the flow rate is greater than the demand, all is OK" Not always true, the flow rate is always associated with a pressure thru the media, if the stock filter is rated at 90 gpm at one pressure loss, and an aftermarket one is rated at 90 gpm at higher pressure loss all might not be okay.

"You start with the flow rate of the filter ( often in the area of 90 GPH more than sufficient) and then subtract for fuel fittings, line size, line length etc." You dont subtract fittings and line sizes from flow rates. The pumps are capable of moving a certain volume of fuel at certain pressure, the volume is dependend on system pressure losses, this is actualy plotted on a pressure vs flow curve. All of the components, including the filter, are system pressure losses that are culmitive. You add up all your losses and compare that to the flow rate of the pump at that pressure.

"The bottom line is that the filter size does not have a direct bearing on flow rate" Again not realy true, media area has a direct corrolation to flow rate. More media area higher flow rate at the same pressure loss, or more media less pressure loss at the same flow rate.

"So if all seems OK, don't go looking for problems" I agree 100%

I am sorry just like to keep everyone honest.

Tim

 

[Texoma]

Thanks guys for all the info. I agree with the comments "if it's not broke, don't fix it". I have experienced two incidents in the past year of owning the boat where the port motor cuts out while underway. I found that there was no fuel getting to the port motor. The first time this happened was shortly after a Yamaha tech serviced all three motors (oil, oil filter, fuel filter, separator filters etc. where changed). I had no pressure at the bulb, so I switched tanks (per the techs instructions), checked the water separator filter for fuel and reinstalled the filter. I got fuel flowing to the motor by pumping the primer bulb and everything seemed to be fine. I had no problem when I switched back over to the aux tank. The tech suggested that he might not have put enough fuel in the filter when he changed it and it might have created an air lock.

I've probably put 75 hours on the motor since then and it happened again this past weekend (both on very warm days). I went thought the same routine as I did last time and the port motor ran just fine again. Its almost like an air lock on the filter and by releasing the pressure everything works fine again...at least for a while. The only difference between the port, center & starboard motor is the size of the separator filter - hence the original question.

Sorry for not supplying the long version of why I was asking the question....

Thanks again guys...all comments and help is appreciated.

 

[seasick]

I agree with most of your technical explanation but not all of it( At least not 100% of it)
Yes, the flow rate depends on pressure . But the pressure is the difference between atmospheric pressure and the effective lift of the pumps. The atmospheric pressure depends a little bit on the barometric pressure and the lift of the pumps or negative pressure depends on the pumps and engine speed to a degree.
Yes a flow/pressure curve applies but bear in mind that the fittings and lengths of hose affect the flow rate since they add resistance to the flow.

In general a filter rated at 90gph using standard testing procedures probably delivers significantly less in the real world but it still more than sufficient flow for your typical dual motor arrangement.

Regarding the pressure loss and flow rate for different size filters: I would hope and assume that when a company published the flow rate for their short and long filter elements, that used the same test procedure and parameters for both. Also bear in mind that different 10 micron filters can still be 10 micron but have very different media areas as you call it.

OK, so my degree is not in fluid dynamics and even if it were, it's been a long time since I practiced engineering, I could be completely off the mark but I would be loathe to admit it!

 

[Grog]

Without cutting both filters open it's all guessing but there is either less room for the filter media or less room for water collection. With less media the pressure drop increases much faster as it filters and you'll loose flow capabilty. Will you ever clog the filter enough to notice it, who knows. Personally I'd change them all out to clear bowl 10 micron Racors and call it a day. If there's water in there I want to see it as soon as possible.

 

[Texoma]

Thanks again guys for all the great comments, info and suggestions. @Grog - agreed! Three new clear bowl Reactors it is...