High diesel filter location or header tank

[Snowpetrel]

Hi,

I am just installing my primary filter. The most convenient place to put it is under the bridge deck above the engine. This means the body of the filter is about 1 foot above the engine, giving me room to get a container under it to catch any diesel when changing it or draining the glass bowl.

Is there any issue with the extra head of pressure it might put on the fuel in the engine supply line, and is it possible that it might drain through the injector pump and injectors or return lines into the cylinders and hydraulic the engine? I guess a header tank has the same potential issue if the fuel shutoff valve is left open?

Any thoughts?

Cheers

Ben

[S/V Illusion]

not an ideal location for a number of reasons. One consideration you may have overlooked is that placing it higher than the tank level is that it makes filling more difficult when you change the filter. Gravity is your friend.

[John Boor]

I don't know of many (any) boats were the tank is above the engine to allow gravity to help. The primary filter should be placed before the engine fuel pump so it will be working on vaccum, pressure is after the engine fuel pump and excess fuel is returned to the tank.

John

[Terra Nova]

You don't want to make the lift pump's work unnecessarily difficult.

[John Boor]

My filter is above the lift pump by actually 12 ins. When I replace my filter I open the drain cock at the bottom of the bowl then crack the top of the filter housing allowing a small amount of fuel to drain (about 2oz) close the drain cock , removeing the old filter slowly and replace with new one slowly then turn on the ignition (I have an electric fuel pump) allowing the fuel to flow through the system and purging the small amount of air in the top of the filter. My Westerbeke 4-107 came with a mechanical lift pump and I would purge the line with the lever on the pump after opening the bolt on the engine filer housing until no bubbles can be seen. I believe that once the lines have been purged of air the lift pump does not work any harder at above, level, or below the pump.

[Stu Jackson]

Originally Posted by John Boor

I believe that once the lines have been purged of air the lift pump does not work any harder at above, level, or below the pump.

If the pump is sized correctly, that is correct.

Put the filter where you can get to it easily and drain it. You mentioned that in your OP, but right above the engine doesn't sound good at all to me, 'cuz if you need to change the filter if it gets clogged and stops the engine, the engine will be hot. A remote location would be far preferred. Our filter is under the head sink adjacent to engine compartment.

[colemj]

Originally Posted by Snowpetrel

Is there any issue with the extra head of pressure it might put on the fuel in the engine supply line, and is it possible that it might drain through the injector pump and injectors or return lines into the cylinders and hydraulic the engine? I guess a header tank has the same potential issue if the fuel shutoff valve is left open?

There is certainly no problem with head pressure and no real way to hydraulic the engine with fuel anyhow.

Our entire fuel tank is well above our engines with no issues. Any increase in head pressure from a small fuel filter will be unmeasurable.

Mark

[MarkSF]

When you change the fuel filter, you need the fuel in the tank to be higher than the filter, so you can bleed out the air. The lift pump won't help you here, as it is after the filter.

When I change my filter, I have to be careful that the fuel tank is nearly full, otherwise it won't bleed.

[colemj]

Many boats have tanks so low that it would be impossible to mount a filter lower than them. Another poster talked about adding an electric lift pump to help with priming. Alternately, one can put a squeeze bulb inline, or simply fill the primary filter housing as full as possible and bleeding through the secondary filter bleed screw as normal.

Mark

[Cheechako]

Originally Posted by colemj

Many boats have tanks so low that it would be impossible to mount a filter lower than them. Another poster talked about adding an electric lift pump to help with priming. Alternately, one can put a squeeze bulb inline, or simply fill the primary filter housing as full as possible and bleeding through the secondary filter bleed screw as normal.

Mark

yeah.. in fact you might even say most boats the tank is lower. (cats excluded!)

I'm not sure I like the filter above the engine though... messy changing filters (all over the engine) , filter problem above the hot engine, engine fire goes right to the filter overhead.... I'd find some other place for it.

[Terra Nova]

Another consideration is to locate the filters where they do not hinder access to engine for service and routine maintenance.

[Panope]

I like having some sort of quick drain valve at the low points of the fuel system. A low mounted filter body would accomplish this nicely.

Steve

[Mr Filter]

You don't want to place the filter that high. If you have any type of air leak the air will be trapped at the highest point. This will cause and air lock

Sent from my SM-N900V using Cruisers Sailing Forum mobile app

[Marqus]

Originally Posted by Mr Filter

You don't want to place the filter that high. If you have any type of air leak the air will be trapped at the highest point. This will cause and air lock

Isn't that why filter housings have air bleed screws? So it may be better for air to accumulate at the filter where you can easily bleed it off?

But I may be missing something since you, as a filter vendor, will know your stuff - so correct my thoughts here thanks.

[Snowpetrel]

Originally Posted by colemj

Our entire fuel tank is well above our engines with no issues. Any increase in head pressure from a small fuel filter will be unmeasurable.

Interesting Mark, did you ever shut off the fuel valve? or was it a non issue? I'm most worried about fuel flowing into the engine via gravity and causing major damage. Air will just stop the engine, fuel might destroy it...

Originally Posted by Mr Filter

You don't want to place the filter that high. If you have any type of air leak the air will be trapped at the highest point. This will cause and air lock

Good Point. I'm not sure if trapped air is likely to be pushed down the line as small bubbles and back out the fuel return on the injector pump? or will it slowly accumulate until it stops the engine? I guess it would depend on the amount of air. Of course ideally air wont get into the system, but if it does it's nice to have it self bleed back though the return line.

Just to clarify, the filter will be outside the engine box, over the transmission area in a place where it can be easily seen, inspected and replaced cleanly. My tanks are low, and I have no real bilge, so bleeding it via gravity will be only possible if the tank is full, and even then only if I put the filter in a very awkward to reach spot.

But I'm heading back down to the boat today, so I will give it more thought. Thanks for all the input.