When fitting fuel filters do you fill them first?

[DavidJ]

Just completed the job Volvopaul style and doing primaries and secondaries on both engines (KAD43's) took just half an hour including tidying up.
So much quicker and less messy than my old filling the filter method.
How long should you run the engines afterwards to ensure no air has got in, or is the effect immediate?

[DAKA]

Surely it dpends on the flow of fuel around the filter? If it fills down the centre, then this is no different to filling with fresh fuel. If it draws from the centre into the injectors then you may have a point. I will take a look at the filters before filling next time.

I know exactly how mine operate as I have taken the trouble to saw both the pre filter and engine filters in half.

I dont know what engines you have or filter.

You mention CMD, Some CMD have stydyn(sp) type filters , quick release plastic ring type ????

If this describes yours then it is absolutely impossible to pre fill safely as there is only one central hole .

I wouldnt worry about it if I was you but I certainly wouldnt allow him to take that short cut next year.

Out in a big rolling sea...........perhaps , but if pre filters are superior quality to engine filters ( FS1000 is a good choice) then theoretically you shouldnt ever need to change engine filters at sea.

[Latestarter1]

Out in a big rolling sea...........perhaps , but if pre filters are superior quality to engine filters ( FS1000 is a good choice) then theoretically you shouldnt ever need to change engine filters at sea.

At last somebody has summed it up!

As a general rule best to fit 'last chance' on engine filter dry and prime with the lift pump for the reasons stated. For CMD Quantum electronic engines it is an absolute requirement to fit filter dry and cycle the ignition switch to allow the electric pump to fill the filter to prevent any likelyhood of allowing contaminatants to enter the fuel pump.

However there are always exeptions, the little Izuzu based CMD 1-7MI-120 has no hand primer and although the fuel pump is the same model as many Volvo engines and is technically self bleeding fitting a dry filter can make re-starting a battery draining exercise and as a result many tecs pre fill the filter.

[Melida]

Just wondered, where does the air goes in the self bleeding no hand pump/primer engines if you don't prefill the on engine fuel filter ?
Is there a purger or check valve exits the air before going to injectors ?

[Latestarter1]

Just wondered, where does the air goes in the self bleeding no hand pump/primer engines if you don't prefill the on engine fuel filter ?
Is there a purger or check valve exits the air before going to injectors ?

Air is purged on the low pressure side of the Bosch VE pump, excess fuel containing entrapped air flows around the pump body and then down the fuel return line.

[Melida]

Air is purged on the low pressure side of the Bosch VE pump, excess fuel containing entrapped air flows around the pump body and then down the fuel return line.

Thanks for the reply.