how many engine hours before CAV filter change?

Burnham Bob

Burnham Bob

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my previous boat had spin on filters and it was a doddle. changed the coarse filter/water separator every season as well as the engine fine filter. the CAV filter on this boat is difficult to get at and much fiddlier to change than a spin on. looking at this season's expenditure already, the spin on conversion will have to wait.

the glass bowl at the bottom of the CAV filter is clean and clear - no water or crud. CAV filter element chaged last year and I doubt if I have done forty hours since then - weather and opportunity to sail never coincided.

what's the forum opinion on whether i should grit my teeth and try to change the CAV filter by climbing into the cockpit locker? the fuel filter on the engine will of course get changed - even if that's not really necessary - its a 10 minute job.
 
Burnham Bob said:
my previous boat had spin on filters and it was a doddle. changed the coarse filter/water separator every season as well as the engine fine filter. the CAV filter on this boat is difficult to get at and much fiddlier to change than a spin on. looking at this season's expenditure already, the spin on conversion will have to wait.

the glass bowl at the bottom of the CAV filter is clean and clear - no water or crud. CAV filter element chaged last year and I doubt if I have done forty hours since then - weather and opportunity to sail never coincided.

what's the forum opinion on whether i should grit my teeth and try to change the CAV filter by climbing into the cockpit locker? the fuel filter on the engine will of course get changed - even if that's not really necessary - its a 10 minute job.
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Is it easier to do now or 1/2 a mile off a lee shore
 
agreed - but if it's not necessary it won't get blocked when i'm off the lee shore............and that's what i'm trying to establish. i know these things go for hours and hours on tractors and diesel lorries.

if the useful life is say two hundred hours and i've done less than forty the filter is less than 25% through it's useful life and the risk of blockage is surely no more than a new filter
 
Burnham Bob said:
agreed - but if it's not necessary it won't get blocked when i'm off the lee shore............and that's what i'm trying to establish. i know these things go for hours and hours on tractors and diesel lorries.

if the useful life is say two hundred hours and i've done less than forty the filter is less than 25% through it's useful life and the risk of blockage is surely no more than a new filter
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Whether or not it needs changing is dependent on the condition of your fuel. If there's dirt in the fuel (or diesel bug), the filter will clog sooner. One good way to find out is to measure how much vacuum the lift pump generates to suck fuel through the filter - as the vacuum increases, it's getting time to change the filter. I have a Racor vacuum gauge fitted, and find I rarely need to change filters.
 
I haven't changed mine for several seasons. No indications that I have a problem, so I don't do it. Not like an oil filter where you have to assume that there is debris inside.

My VW diesel van had a fuel filter that I did not know was there. i did 100,000 miles in it before I found it. Symptoms are unmistakeable when it needs changing, revs are limited under power but not in neutral.
 
thanks - i rather thought that these were more robust with a longer life than one season of a few hours motoring. as far as i can tell the diesel tank itself is clean and there is no diesel bug at the moment but i am going to use marine 16 treatment as a preventative - to avoid sailorman's blocked filter on a lee shore......
 
Burnham Bob said:
thanks - i rather thought that these were more robust with a longer life than one season of a few hours motoring. as far as i can tell the diesel tank itself is clean and there is no diesel bug at the moment but i am going to use marine 16 treatment as a preventative - to avoid sailorman's blocked filter on a lee shore......
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make sure ite not 1/2 way along Mersea Island on equinoctial springs :rolleyes:
 
I change my engine filters every 400 hours unless there are signs of trouble in the sedimenter. I go through a couple of tons of fuel each year, and always use Fuel Set. My sedimenter has no filter element, so I can see the muck, yours may be almost blocked you can tell by the weight when you remove it. In any case in the past when I had an access problem I always moved it somewhere easier to get at.
 
Burnham Bob said:
my previous boat had spin on filters and it was a doddle. changed the coarse filter/water separator every season as well as the engine fine filter. the CAV filter on this boat is difficult to get at and much fiddlier to change than a spin on. looking at this season's expenditure already, the spin on conversion will have to wait.

the glass bowl at the bottom of the CAV filter is clean and clear - no water or crud. CAV filter element chaged last year and I doubt if I have done forty hours since then - weather and opportunity to sail never coincided.

what's the forum opinion on whether i should grit my teeth and try to change the CAV filter by climbing into the cockpit locker? the fuel filter on the engine will of course get changed - even if that's not really necessary - its a 10 minute job.
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The reality is that "it depends"`I have seen filters block inside 10 minutes when there is a bug contamination. But lets be sensible; if the engine is running on clean fuel then 400 hours would not be unusual. I have always used fuel set and at the beginning I changed my filters at the recommended time. Then I started to cut the old filters up to see what they had caught - answer; almost nothing just a little bit of red sand (it comes in with the crude oil). So IF you are confident that the fuel is clean AND the engine is running OK leave it alone.
 
One of the benefits of sailing in Greece is that most of our fuel is delivered by mini-tanker from petrol stations. The turnover is high, the storage tanks seem to be clean and consequently the fuel quality is good. Problems are common with barge type fuel storage in marinas where there is often water contamination and the fuel may have sat in there for a very long time.
 
I believe it is just as important to keep the tank cleam
I ensure that all fuel is passed through a filtered funnel & i open the tank up every few years to check if there is any problems.
Filters are fairly cheap if bought from places such tractor dealers. I get mine from Does at Ulting
So if there is any doubt why not just change the filter

I had problems accessing the CAV unit so i mounted it on studs with 2 butterfly nuts to allow quick removal.
That way i can hold the unit over a bucket whilst dismantling plus i can get at it easy to check i have not distorted the seals etc
Damned thing still leaks sometimes though!!!
Solved by checking diameter of filter as suggested on another thread. They vary by up to 1 mm in diameter
 
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>Not necessarily, the crud isn't visible, as it's inside the filter.

From experience if the filter is getting crud in it then there will be some in the bowl because the diesel surrounds the filter and some crud will drop in the bowl before being taken out by the filter.
 
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