Saltram31
Well-Known Member
I have a Raycor type bowl filter in series with a CAV filter then to the secondary. Would this restrict flow to the HP pump? I am getting rid of the CAV, but was leaving it until the end of season.
Primary diesel filters in series?
- Thread starter Saltram31
- Start date
geem
Well-Known Member
Not unless they are blocked
Bandit
Well-Known Member
Most modern engines have a fuel filter on them already so a Racor so call it the remote filter is the first in line.
With reasonable quality fuel you do not need three.
The engine mounted filter is a fine filter.
The racor is there to drain out water and is a rock stopper ie take our the big bits so use a 30 micron not a fine filter or it will block, the engine mounted filter is fine and will take out the fine stuff.
Treat your fuel with a quality biocide such as Grotamar 81 or Marine 16.
If you have a problem with water in the fuel clean out the tank.
Check your Racor for dirt and bug and drain off water.
Carry spare Racor filter elements.
Get to know your fuel system.
With reasonable quality fuel you do not need three.
The engine mounted filter is a fine filter.
The racor is there to drain out water and is a rock stopper ie take our the big bits so use a 30 micron not a fine filter or it will block, the engine mounted filter is fine and will take out the fine stuff.
Treat your fuel with a quality biocide such as Grotamar 81 or Marine 16.
If you have a problem with water in the fuel clean out the tank.
Check your Racor for dirt and bug and drain off water.
Carry spare Racor filter elements.
Get to know your fuel system.
geem
Well-Known Member
I would use a 5 micron filter in the Racor. They are large surface filters with plenty of potential to catch debris. The idea is it stops sediment getting to the injection pump. You should not be worried about it blocking. It is there to do a job. The secondary filter should stay clean and not often need changing. It is there to catch any sediment that may be disturbed every time you change the Racor. It's your backup, but they typically have a tiny surface area compared to a Racor filter element. If they are doing any work at all, they will block pretty quickly
roaringgirl
Well-Known Member
If you have 2 external filters in addition to the small one at the HP pump, you have a great opportunity to make a hot-swappable system. With the addition of a small amount of plumbing you can run through the Racor and bypass the CAV, if the Racor blocks, you turn a couple of valves and bypass it, and go through the CAV instead, you can then change the element in the Racor while the engine is still running.
B27
Well-Known Member
I think the best idea is to know that there's not enough crud in your tank to possibly block your filter.
Draw your fuel from the bottom of the tank, get any water into a filter and deal with it.
That's from a small sailing boat perspective, <50 litre tank etc.
With a long distance cruiser, big tanks, I would think about filtering fuel before it went into a 'day tank'.
I have seen a few yachts with big old tanks, the pickup is inches above the tank floor, so over the years a volume of water and crap can accumulate, enough to block all the filters you care to swap.
You can trap most of the big lumps and water with a simple cleanable gauze in a clear bowl.
https://www.ebay.co.uk/itm/182040299537
That will let you see what's coming out of the tank.
Draw your fuel from the bottom of the tank, get any water into a filter and deal with it.
That's from a small sailing boat perspective, <50 litre tank etc.
With a long distance cruiser, big tanks, I would think about filtering fuel before it went into a 'day tank'.
I have seen a few yachts with big old tanks, the pickup is inches above the tank floor, so over the years a volume of water and crap can accumulate, enough to block all the filters you care to swap.
You can trap most of the big lumps and water with a simple cleanable gauze in a clear bowl.
https://www.ebay.co.uk/itm/182040299537
That will let you see what's coming out of the tank.
geem
Well-Known Member
Our 500 litre tank has a 500mm diameter manhole access lid with a 1 inch bronze access hole fitting in that. We can sample the bottom of the tank and 'vacuum' it to remove crud periodically. I normally check it every 6 months. Water is easily removed and also sediment. I have never seen more that an eggcup full of water in 11 years of checking the tank.
We use 1/4turn Donaldson high capacity fuel filters with a water sensor on the first filter. Both filters are as big as Racor filters.The first filter does all the work and is the only one to actually get and sediment in. They can be changed in less than 30 seconds so no need for parallel filters and the injection pump is self bleeding. I don't change the second filter very often, maybe every 4 years. Every other year for the first filter
