Friday, 13 June 2014

Replacing diesel filter: no fuel from tank when stopcock opened

It was all going reasonably well. I'd replaced the broken plastic drain tap on the bowl under the filter with a bolt and copper washer. I'd replaced two of the O-rings and both the large rubber washers. (But I couldn't find where one of the three supplied O-rings was supposed to go - when I asked a neighbour he said I didn't need to replace any of them.)

With it all bolted back together I turned on the fuel stopcock and opened the bleed screw on the top of the filter housing.

Nothing happened.

I was expecting gravity to force the fuel through the filter and out of the bleed screw, but there was no sign of anything happening. The only thing I could think was that there was a blockage in the pipe to the stopcock, so I undid where the pipe connects to the filter, pushed a plastic hose on and blew. There was little resistance, only the weight of the fuel, and I could hear my breath bubbling in the tank. No blockage, then. But still no fuel came out of the pipe. What was going on? (The above photo shows the pipe disconnected and the fuel switched off.)

And then I realised that the fuel line from the tank goes up before it comes down. In other words, it has to siphon out past the stopcock.

Well, no-one told me!!! Is this standard practice? I don't recall Tony Brooks mentioning it in his training guide.

Here is the outlet from the fuel tank (mostly hidden behind the big plastic hose) only just below deck level. There are actually two pipes: the one on the left is the leak-off pipe carrying fuel back to the tank from the injector pump.

How was I going to get the siphon going? Same as before, except I had to suck, not blow. Fortunately my neighbour had returned to see how I was getting on, so I got him to stand by to turn off the stopcock before I sprayed too much diesel around the engine hole.

I can report that diesel has the consistency in the mouth of olive oil, and a slightly similar taste. I shan't be cooking with it, though, and I can't say that I'm looking forward to my next tasting.

Quite a bit of crud came through, probably as a result of my having stirred things up when I blew into the tank. After the worst had gone I reconnected the pipe to the filter housing and switched on the stopcock. This time fuel immediately started gushing out of the bleed screw, which I hastily screwed down.

At last I might have successfully replaced a fuel filter. Horrible job. And there's one more to go: there's a spin-on filter mounted on the engine.

To make sure I hadn't introduced air into the system I started the engine which, thankfully, ran perfectly smoothly for half-an-hour. Then I went to Ally and Ben's house where I had a drink of milk!

When I returned to the boat in the evening there was a strong smell of diesel. This I put down to my exploits earlier in the day, so I wasn't too worried. In the morning the smell was still there, and when I felt around the filter I detected a fair amount of wet. I managed to tighten the fuel pipe connector a bit more, and the central bolt holding the filter unit together a lot more. This was on Monday/Tuesday. When I left the boat on Thursday the outside of the filter was dry and the smell had diminished significantly, so I'm hoping the job's a good un.

As well as being horrible.


Jim said...


Halfie said...

Merely to cleanse the palette. Didn't want to ruin the taste of beer.