Primary fuel filters - again!

[DrBob]

Hi All, anyone out there give me some advice on changing my primary fuel filter? I search the forum records and picked up a lot of advice which helps me piece together my questions. On Saturday I did a full engine service on the boat (a 40 foot AWB with a Volvo MD2040). All went ok apart from the primary fuel filter.

First of all the top of the primary fuel filter is about 6 inches higher than the top of the diesel tank (which by the way is nearly full). Boat is around 18 months old and this was the first time I have changed this filter. The filter is a CAV type with a glass bowl at the bottom – new with the boat so the filter fitted was a Volvo type – and my replacement was a Volvo one. First thing was the nylon plug on the bottom was welded solid and snapped off leaving the thread in the base of the unit with a good seal- hence I could put it back together again.

After changing the filter over, I primed the system with the lift pump (also changed the secondary filter) although it took ages to “lift” all the fuel in to fill the primary filter. Engine started fine and runs ok. Problem is that the webasto heater (new last year) – which is fed from the second outlet on the top of the primary fuel filter – has not run properly despite turning on and off at least 10 times today (fault code saying not lighting hence almost certainly air in the feed pipe - between the filter and the heater pump?). It ran for 20 mins then stopped and has not started properly.

From previous threads I think what I need is a Racor type filter with an integral priming pump and that way I can bleed the air out of the feed to the heater pump. Any thoughts?

The CAV filter replacement was a pain and I will not look forward to doing that at Sea hence my interest in the Racor. First option is to get a conversion kit (from ASAP) but that wont have the priming pump – so is there another way to prime the heating system?
Do the Racor filter units come with multiple outputs on the top – I cant see from the ASAP site- and in the same orientaion as I have now to ease fitting?

Finally its difficult to see what the Racor system is. As a spin on filter, can you fill up the filter before spinning on so reducing the priming needed? Is then the filter a paper type element that fits into a housing – I cant work it out from the pictures on the site?

So to summarise
- I want to replace the current filter unit ‘cause I no longer have a drain valve and it was a pain to change the filter
- I need to be able to prime the heating circuit easier
- but I am not sure whether to get the conversion unit or a full unit
- And finaly is it worth getting a duel unit that can be switched at sea?

Any takers?

Dr Bob

 

[MrCramp]

I have my filter lower than my fuel tank and I would want to see whether your filter could be moved to the lowest position possible. If your fuel filter (and in my case engine) are gravity fed, unless the tanks is nearly empty, then it makes life much easier.

 

[DrBob]

There's not much room to lower the filter, maybe 6 inches max but then there's no room to drain stuff out of the bottom - I supose I could raise it up to do that! I still would problaby be just higher than the diesel in the tank unless I topped up the fill tube.

Thanks for the input.

Dr Bob

 

[ms1]

you can get CAV filter spares from ASAP Supplies, including the drain plug. They also do a CAV type filter with an intergral primer. I have these; they are very effectiive. Between these and the fuel tank I have Racor 500 filter which is so easy to change it is not true. The Racor unit is not cheap but it is a gem ..... it works so well that the CAV filter barely needs changing.
My Racor filter change is:
unscrew the top, remove the filter, insert new filter, add a little fuel , replace the central T screw.
Actually the CAv change does get easier every time you do it

 

[ianwoods]

Put non return valves on either side of the primary filter. This will mean less of the system to bleed. You might also buy a diesel filter housing with an integral pump- an earler article mentioned a Fiesta car one circa 1997 as being suitable.

 

[DrBob]

Martin,

I am somewhat tempted to leave my CAV filter in place and put a racor 500 infront of it which may mean less air getting into the heater circuit. Is that the way round yours is?

Dr Bob

 

[ms1]

yes
tank, stop cock, Racor 500, CAV with integral primer, engine.
30 micron filter (red) in the Racor and a 10 micron on the CAV. I keep changing the CAV but since I fitted the Racors the filters stay incredibly clean.
The Racors have their own threaded connector (not BSP) I think its an American thread so when you buy you need to specify whether you want straight or elbow. I used ASAP Supplies they were very helpful. I had to use the MA500 model as I wanted see thru bowl (not usually allowed on the Thames - boat safety scheme) but the MA version has a metal heat shield and BSS approval. Other models have metal bowl. they are expensive. Racor also do other models with spin on filters etc, but I have no experience of these to be honest. Be aware the MA500 is quite large .. but a filter change in less time than boiling the kettle.

 

[ms1]

by the way ASAP do a conversion CAV to RACOR spin on (quite expensive)

 

[Malish]

Give serious consideration to a switchable system with independent filters - ASAP can supply the bits for a switchable CAV-filter based system or you can pay a small fortune for a racor all in one unit. More than once have I heard the tale of a yachtsman approaching harbour after a lumpy journey only to have his engine fail due to stirring of sediment in the tank. In such circumstances a switchable unit could make the difference between a call for help and a safe arrival.

 

[DrBob]

Ok guys,

thanks for the help. Some good stuff here as always.

I will look at a racor unit at our local supplier and think about getting swichable system.

Dr Bob