Beware the amateur mechanic,

[alan_fincher]

It should have been an easy task - replace the diesel fuel filter on a BMC 1800.

 

Didn't get off to a great start, when, although I knew fuel would p**s out everywhere, I failed to catch most of it.

 

Not daunted, I mopped up, fitted new filter, and attempted to bleed the system.

 

I had not disturbed anything on the high pressure side, so expected to get away with the two bleed points on the filter, and the 2 on the low pressure side of the injection pump.

 

All were passing copious amounts of fuel, so I hoped engine would start. It did, ran for about 30 seconds, and stopped. Much cranking, and zilch. Re-bled all previous points - still zilch.

 

So decided I need to bleed high pressure side as well.

 

Manual says next bleed point is the one in the middle of the bolt that secures the banjo outlet from the pump to the rear cylinder.

 

Loosened bleed screw, and cranked, and cranked, and cranked - no fuel. (Cranking now starting to get worryingly slow).

 

In desperation removed bleed screw completely, and cranked some more. And some more.

 

Suddenly a spurt or two of fuel, neatly hitting my leg. Replaced bleed screw, and, (now cranking very slowly), engine fires up, and runs.

 

Sounds OK, except....

 

Fuel now being ejected from the bleed screw I've just replaced, (or more accurately from a small bleed hole in one of the flats of the larger "banjo bolt", in which it sits.

 

Dismantled it all. A bit surprised that the bleed screw has a flat rather than conical end. There is nothing down the hole to stop it seating.

 

Put it all back together, and tighten it as hard as I dare.

 

You've guessed it - fuel still p**sing out the hole in the banjo bolt.

 

Turned off fuel, went home, and phoned Calcutt.

 

The bolts are not items sold in their own right - they only come with a complete injector pump.

 

The story does have a happy ending, but, before I tell what was wrong, can anybody guess why it was leaking like a tap.

 

I felt fairly stupid when I found out!

[NB Alnwick]

The story does have a happy ending, but, before I tell what was wrong, can anybody guess why it was leaking like a tap.

 

It was a tap?

[alan_fincher]

Erm,

 

Not really - it was meant to be a closed one, if it was.

 

Fortunately someone at Calcutt came up with the answer, (which eluded the mechanic at our marina). I'm kind of guessing someone will know what had happened.

 

(OK, it's not as interesting as Moley's quizzes, I freely admit!)

[Nickhlx]

when you un-did it you failed to notice that the sealing washer had done a runner into the bilge and upon re-assembly you could hear it (albeit very faintly) laughing its sock off somewhere under the engine ?

 

Nick

[alan_fincher]

No, no sealing washer, but you are close!

[NB Alnwick]

I still think you had a form of bleed tap - it appears that the bleed hole [in one of the flats of the larger "banjo bolt"] needed to line up with something for it to bleed. When you loosened it off completely and then re-tightened it, you failed to line it up in the closed position.

 

Of course I am only guessing - our in-line CAV pump has a slightly different arrangement.

[almostafloat]

when the filter was off some dirt found its way thru and stopped the screw seating properly

[alan_fincher]

No sorry Graham - nothing like that.

 

Nick was much closer, but there was no missing washer, as such....

[NB Esk]

When you removed the bolt, it allowed the fuel to eject a small ball bearing, which should have provided the seal.

[almostafloat]

whos this graham

[NB Alnwick]

When you removed the bolt, it allowed the fuel to eject a small ball bearing, which should have provided the seal.

 

That sounds logical! Or perhaps spring plunger - come-on don't keep us in suspense any longer.

Edited April 25, 2008 by NB Alnwick

[alan_fincher]

When you removed the bolt, it allowed the fuel to eject a small ball bearing, which should have provided the seal.

Absolutely, that man!

 

It's a shame you don't moor next to me - I could have done with someone to ask!

 

No springs, no washers, but the small bleed screw does bear down on a small ball bearing, which is what seats into the housing on the banjo bolt.

 

Two amazing bits of good fortune...

 

1) We actually found the damn thing, once we knew it should exist. (Helpful as we had no idea of correct size)

 

2) Tightening the bolt down hard into the ball bearings seating, with no ball present, didn't seem to have damaged it.

 

We live, and learn.

 

Only took most of the day!

 

Alan

[NB Alnwick]

We live, and learn.

 

Indeed! Thats what makes it interesting.

[DHutch]

Ahh, very good.

- We have cylinder relief valves like that. Ball bearing held into a conical hole by a stiff stainless spring.

 

 

Daniel