Pre/Primary Fuel Filter Change Frequency

[mark1882]

Hi

We are en-route to the Med and have invarably found our selves with either no wind or wind in the wrong direction which has meant we have had to do much more motoring than we had expected.

This has resulted in us having to do more minor engine service of changing oil and filters etc. I am normally doing the oil and oil and fuel filter changes every 100/120 engine hours. I have received some contradictory advice on the frequency of changing the fuel pre filter. I have a Racor pre-filter with water separator and it has been suggested that I should either change this every time I change the engine fuel filter ie every 100/120 hours or every other time I change the engine fuel filter so any advice on this would be appreciated.

Thanks

Mark

 

[RichardS]

I only change my Racor filter when it's looking a bit dirty which is usually every few years unless you have had a diesel bug attack - which will show up as dirt anyway!

I know it's not a direct comparison but think how often you change the fuel filter on your car. Possibly never as many people don't know that there is even a filter. I changed the one on my car for the first time a couple of years ago. By then the car was 15 years old!

Richard

 

[ghostlymoron]

I change mine annually and generally they don't need it. Some sailors put a pressure gauge in the system which shows when the filter is getting blocked and then change on a performance rather than time basis.

 

[KellysEye]

Changing the fuel filter(s) is not linked to engine oil change which are specified by the manufacturer. As said keep an eye on the filter bowl for both water and dirt, if dirty change the filter. Which is what we did. In the Caribbean dirt and water in diesel was endemic so I put in a mobo system two filters in parralel with on/off switches, if there is dirt build up then just change to the second filter. Bleed both filters when you fit them.

 

[GrahamM376]

I change primary fuel at 200 hrs and oil change & filter around 100 hrs and before laying up for a while in winter.

 

[geem]

Oil changes for us are every 500 hrs or 12 months, which ever comes first. I change the prefilter every 12 months an if it's clean I don't check the main fitter on the engine until 3 years old. When I checked this one it was perfectly clean so I refitted it.

 

[Nigelb]

I have just fitted a Raccor fuel filter and planned to stick with the Beta recommended service interval for the Primary filter and inspect the Raccor periodically for contamination and replace as necessary. My logic is that the Raccor is easy to inspect and is 30 microns as opposed to Primary fuel filter which is 10 micons. I have not had any problems to date and I view the Raccor as a bit of additional insurance/fuel conditioning as I believe the Beta units and most marine diesels are fairly forgiving in terms of fuel quality. Will endeavour to source fuel from reliable sources and keep tanks topped up and hopefully will not have to resort to fuel additives etc.

 

[Topcat47]

Filters are cheap, as is oil. Engines are expensive. The best way to keep engines healthy is to regularly change both oil and filters. I change mine every year, need it or not. I've never had a spot of anything in the fine fuel filter except the times I got a dose of diesel bug. Similarly with the primary fuel filter. As for the canister lub oil filter, I doubt whether that's ever needed changed. Out of curiosity, I cut one up after a season in which I'd actually used two full tanks of diesel (Snark is a sailing boat, after all) it was discoloured but there wasn't much in the way of solids. I doubt you'll find anything different. Still for peace of mind, changing filters is cheap insurance. Do what gives you peace of mind.

If you're in doubt about the quality of fuel you're buying, I have a Mr Funnel. I use it when I top up from my emergency fuel can as I can easily spot if there's water present. Only twice have I had contaminated diesel fro a fuel barge, once in the Hamble and once in Portsmouth Harbour, both came on board with about 20% water. After the second time, I used the Mr Funnel for about two years whenever I filled up but it really slowed down the fuelling process and nothing showed up from the storage tanks.

 

[johnalison]

Yearly for me but every 100hr for the oil + change. It would be easier if the hour meter still showed anything, so it's about three fill-ups worth.

 

[lpdsn]

I fitted a vacuum gauge between primary filter and lift pump. I change the primary filter based on monitoring that.

 

[prv]

Filters are cheap

Depends on the filters . I neglected to consider this aspect when fitting a new Racor filter housing on Ariam, and the cartridges for it are uncomfortably pricey.

Fortunately with a suction gauge between them and the lift pump, I can change only when required.

Pete

 

[ribrage]

All sound advice -

Our personal experience , we have an old steel yacht nearly 40 , our tanks are not the cleanest , in the UK Id sail off the mooring and back onto my mooring whenever possible and maybe did filters once a year if they needed doing , now we are in the med we are using the engine a lot more - maneuvering - charging - no wind , as such the frequency at which I have to drain the separator and swop pre filters has increased considerably, so I have fitted an additional water / dirt separator that doesn't have a replaceable filter fitted, its a reusable filter , just remove it wash it in clean diesel and refit it - this has saved me some money when it comes to Racor filters as I don't have to change the Racor filter as often.

rambling on :

When we re engine the beginning of this year I fitted all the filter heads ( water separator - pre filter - diesel heater filter - fuel transfer filters and extinguisher ) onto a two position slide mount and fitted with longer fuel hoses so they can easily be slid up clear of the engine room for routine maintenance, this has made life much easier - no scrabbling around with torches trying to see through a red stained bowl and trying to guess whats water , whats dirt and whats fuel , its all at eye level , to drain them simply put a bucket under the whole lot and open the drain screws,change filters if required, to refill drop the whole lot back into the lower position and RE open the fuel taps , they refill on their own as they are lower than fuel level, tighten the racor tops and hey presto all done.

cant claim the idea- All my workboats are factory installed the same fashion

 

[Stemar]

Changing the fuel filter(s) is not linked to engine oil change which are specified by the manufacturer. As said keep an eye on the filter bowl for both water and dirt, if dirty change the filter. Which is what we did. In the Caribbean dirt and water in diesel was endemic so I put in a mobo system two filters in parralel with on/off switches, if there is dirt build up then just change to the second filter. Bleed both filters when you fit them.

I fitted a similar system about 7 years ago after a rather traumatic putputput - put - - put - - - silence, just when I really didn't need it. I used spin-on filters from a car breakers and the whole thing cost less than £30 to set up.

Since I can now switch to a new filter in a few seconds, I didn't change the filter the first year. I was a bit busy the second year too. I really must change them both this year, though, as they're getting a bit too rusty for comfort.

 

[geem]

Depends on the filters . I neglected to consider this aspect when fitting a new Racor filter housing on Ariam, and the cartridges for it are uncomfortably pricey.

Fortunately with a suction gauge between them and the lift pump, I can change only when required.

Air filters (we have two), Fuel pre filter and fuel filter for our Perkins are £80. No need to change them if they don't need it. The engine won't know! Air filter has pressure gauge so the engine tells you it needs changing. I inspect the fuel filter myself! Filters are spin on and easy accessible so no major issue if I ever had to change them in a hurry. We have an engine room rather than a engine space. We can standup in the engine room so I job that isn't too unpleasant unlike my last boat where I had to stand on my head to do anything.

Pete

 

[adwuk]

Our primary filter was completely clogged this weekend, resulting in air in the system, and forcing me to learn how to replace primary and secondary filters, as well as bleeding the fuel system. Fortunately, we hadn't actually cast off when the engine started to splutter! We also took the opportunity to open the drain on the fuel tank sump and extract some extra gunk. A pain at the time, but happy that we could now do it more quickly if we had too.

As I suspect a case of diesel bug, I have started to think about a rudimentary fuel polishing system. 12v pump plus Racor 500 filter, taking its feed from the fuel tank sump outlet and returning through the fuel tank filler - run for a couple of hours while tied up in our berth. Does anyone do anything similar? I'm guessing this would reduce the frequency of change for the main fuel filters as well.

 

[Nigelb]

This will need to be checked but I recall reading that a significant percentage of fuel is returned to the tank via the return line so over time you are in fact polishing the contents of the tank. Personally I have always liked the idea of parallel Raccor filters and the ability to switch lines in an emergency but I think it is an expensive option given the actual risk.

 

[GrahamM376]

This will need to be checked but I recall reading that a significant percentage of fuel is returned to the tank via the return line so over time you are in fact polishing the contents of the tank. Personally I have always liked the idea of parallel Raccor filters and the ability to switch lines in an emergency but I think it is an expensive option given the actual risk.

Our electric pump starts as soon as ignition switch is on and runs at constant speed regardless of revs so, at low revs I suspect more is being polished and returned than burned.

 

[geem]

Don't confuse polishing with filtering. Polishing is a little more sophisticated. A good polishing system moves circa 5%'of the tank volume in 24 hrs. The polishing system suction pipe should be taken from the lowest point and returned at the top of the tank on the opposite side. Commercial systems we deal with run 24/7. The system should agitate the bottom of the tank where particles settle and suck them into the polishing system. The polishing system would normally consist of pump, centrifuge filters, water separator and element filters.
On very large tanks these systems don't work due to the inability to agitate the particles on the bottom of the tank. On these tanks circa 100,000 litres polishing is usually done every 6 to 12 months by mobile unit with a huge lance that is inserted in the inspection hatch and they literally Hoover the bottom of the tank.
I don't have a polishing system on my boat but on my last boat I caught the nasty diesel bug. I made up a portable filtration system with a large electric pump, some copper pipe, flexi pipe and a high capacity clear filter that are usually sold for biodiesel filtration. I inserted the copper pipe into my fuel tank inspection hatch and hoovered out the dead diesel bug after I had treated it with biocide. It took about three hours but I didn't need to empty the 36 gallons of fuel out to clean the tank. At the end of the season I removed the tank and cleaned it thoroughly. I now carry this portable system onboard in case it ever happens again.
It would be quite feasible to build a proper polishing system but but to be really effective you would want to flow a lot of fuel assuming it would only run when the engine was on. Assuming that the fuel going through the engine return pipe is polishing the system is not realistic unless you use your engine all the time and the fuel supply system is grossly oversized

 

[Nicholas123]

After finding that I had half inch of water at the bottom of my water separator/filter a couple of weeks ago even though the engine had only run about 10/20 hours since I last did it. I started to get concerned about the diesel bug/gunk/amount of water at the bottom of my fuel tank. (I only have had about twenty litres slopping about in the bottom of a large maybe 100 litre plastic tank for several years) so I poked my syphon pump pipe in through the inspection hatch & pumped out a few gallons. When I transferred this to a clear plastic container I could see no sign of any water or real contamination whatsoever.

Conclusion: Maybe the diesel bug only effects metal tanks where condensation would obviously be an issue.

 

[adwuk]

@geem - thanks, useful insight. I was planning to take the feed for the 'polishing' pump from the fuel tank's bottom drain, so it would be filtering from the bottom of the tank. The intention was then to pump through a coarse filter (reusable one) on a Raccor 500, which also does water separation I believe. Still need to investigate that. The return would then pump back into the tank via the filler cap (removed for the operation). Maybe a bit of overkill, and I may just get a tank cleaning firm to come and do a proper job as you say.

@Nicholas123 - I have a built in GRP tank, and have the primary filter was clogged with black stringy gunk, which I assume is dead diesel bug or its by-product.