Am I bleeding correctly?

[pcatterall]

Just installed a new sedimeter and not certain if I am bleeding it the correct way.

The componants are below fuel level but the fuel pipe goes up inside the tank then down to the first filter so I am treating it as a 'nongravity system'

The sedimeter is the first item ( I changed it as the original one was not glass and had no drain screw) My new one is just a direct replacement. I have got the in and out pipes right way round and all connections are tight.

Following the sedimeter is a CAV type primarry filter with glass bowl and drain. Next via the manual pump is the fine filter.

After the fitting the sedimeter bowl is empty and the primarry filter still full.

I understand that I should bleed at the fine filter only using the manual pump.

When I start doing this fuel is expelled at the bleed screw but there is no sign of flow into the sedimeter.
Will I have to pump all the fuel out of the fine and the primarry filter before anything happens ( very difficult to catch the fuel)
What is a rough estimate of the number of pump lifts That should be needed? ( just to give me an idea)

I ran the engine for a couple of mins in the hope that it would start to draw fuel through, I expected to see fuel coming into the sedimeter and out of the primarry filter, I thought I could then cut the engine before air got through and save some pumping. However no fuel came into the sedimeter so I switched off.

Yes there is fuel in the tank and the switch is open.

Any tips and advice most gratefully received

 

[pvb]

What make/type of sedimenter have you fitted? And why, because the glass bowl type CAV filter is effectively an agglomerator which will do the same job.

 

[gordmac]

I would have thought running the engine would draw fuel through, if it isn't I don't see how manually working the lift pump would do any better. Drawing air somewhere? Not run long enough?

 

[pcatterall]

Ahh PVB on the ball ( and quick!!) its just a basic glass bowl. Fitted it as it was easier than trying to by pass the original non drainable one, plus the CAV drain is a swine to get at.
Cheers

 

[wotayottie]

You asked at the right place. We are all bleeding correct here. ! Me most of all.

1/ run the engine until it has used up the fuel in the secondary filter and stops. In doing so it should have sucked diesel through at least part of the new pipework

2/ tedious though it is, waggle the little lever with the bleed screw open until non bubbly fuel comes through. no fixed number of waggles. Depends entirely on your situation.

3/ if 2 doesnt work you have a leak

 

[pvb]

Ahh PVB on the ball ( and quick!!) its just a basic glass bowl. Fitted it as it was easier than trying to by pass the original non drainable one, plus the CAV drain is a swine to get at.

Not sure it's going to do much then. I thought it was the passing of fuel through the filter medium which caused water in the fuel to form droplets large enough to settle in the bottom of the CAV filter's glass bowl. Incidentally, I have CAV primary filters with glass bowls, and I have never found any water in them!

 

[pcatterall]

Sorted!! many thanks all. Must confess...... I had not tightened the glass bowl bolt enough. The sedimeter came with dire warnings about overtightening. Anyway I gave it some more wellie ( using the bolt and spanner rather than the knurled knob at the bottom).
Started engine and immediatly fuel started coming into the bowl.

Question arising!!
I kept engine running for 20mins and it did'nt stop, I thought it would when the air from the bowl reached the engine.
I recall that when we used to empty out the old sedimeter( the one with no drain plug) we just used to start up and run with no bleeding so what happens to the air?

Thanks again

 

[wotayottie]

Some engines are partially self bleeding ie they suck enough air and fuel through to give themselves enough fuel to run on provided you have got the fuel as far as the secondary filter.

 

[pcatterall]

Its a perkins 4108. I will run another 15mins today just to make sure its ok. I guess, though,that the fuel in the pipes and the primarry and secondary filters would not exceed a litre so running 15mins yesterday should have removed any air?
thanks again

 

[KellysEye]

> I will run another 15mins today just to make sure its ok.

Make sure you run it 1,200 revs+ in gear it sucks much more fuel through. At tickover or low revs it needs to be run for at least an hour and even then you can't be certain there is no air in the system because there is no load on it. We had many leaks when the boat had a copper pipe fuel system (which I subsequently changed) and I learnt all that the hard way.