Diesel Lines Blocked

[smitch6]

after spending all day yesterday trying to bleed my bmc after replacing the filters, i gave up and tried again today.

i have a hand pump that i use to get the oil of of the gearbox etc.

I connected it to the line going into the lift pump and pump, and it created an amazing pressure, so that points to a sealed system.

so i dismantled the sediment filter and cleaned that ( i now have a wooden floor that has diesel soaked into it )

there was a little bit of crud in the filter so i went further up the line to the shut off tap,

there was a bit of crud in there also, but more worrying is i had the tap off in my hand and no diesel was coming through the pipe from the tank.

the first 20" or so from the base of the tank to the tap is blocked.

i am going to get an air compressor on it next week, but i am wondering is there another way to clear it?

as if it happens while cruising i'd be stuffed

i've got to be very careful as i've put in 150lt of diesel a few months ago, annoyingly

i did think maybe i could get a thing flexible rod to clear the pipe but not sure where from or what type

[grendel]

might be worth checking for the dreaded diesel bug as that could be what is crudding up your pipes, do you have an inspection hatch or camera on a snake thing you can check with? either that or its just sediment on the bottom of the tank.

[smitch6]

i have put in an additive a month or so ago for bug, so i'd say its sediment

[grendel]

could well be, its had all winter to settle out 

[D46]

Having had this very same issue and unfortunately while cruising which stopped me dead , that was traced to a carpet of curd on the bottom of the tank , unfortunately the tanks builder had made the supply pipe way too long being less than 10 mm off the bottom , fine with a very clean tank but anything in there and there will be it gets sucked up blocking it entirely , my solution was first make an inspection hatch , then because the original pipe couldn't be shortened as it was welded in put in a new supply pipe this time 30mm off the bottom and block off the original one , after pumping out 3/4 of a tank I got to the route of the issue , that demands a wet and dry vac as it breaks up as you move it , once cleaned the fuel was filtered several times till clear and treat with a shock dose of Marine 16 , additives don't actually remove the problem they do leave this carpet behind as in dead diesel bug which needs removing .

Hopefully you supply pipe isn't like mine was and too long and your tank has inspection hatch if not you really need to make one , going one step further I also incorporated a removable bolt with copper washer which is a very Handy dip stick hole .

[smitch6]

nope it's not like you're, my supply pipe comes straight out of the bottom of the tank, about 1" off the bottom,

and there is no way in hope that i could make an inspection hatch, 

i wanted to put a gauge in and realised it couldn't happen, let along put a hatch in.

i do have a sediment filter, but that is about 2m along the line

[D46]

6 minutes ago, smitch6 said:

nope it's not like you're, my supply pipe comes straight out of the bottom of the tank, about 1" off the bottom,

and there is no way in hope that i could make an inspection hatch, 

i wanted to put a gauge in and realised it couldn't happen, let along put a hatch in.

i do have a sediment filter, but that is about 2m along the line

Oh dear that not good news  , as the pipe is 1" off the bottom and side entry it would surgest that onless it happened on a very choppy river that's the level of the curd , it may be that it's going to need specialist cleaning probably steam cleaned , first job is to suck as much fuel out via the filler a little at a time then lower the pump pipe when it can't get any more fuel , hopefully that's possible , but given that alot of tanks have quite bent filler hoses it might not be easy to do , if you can get most of it out then for m there on in your sucking up the curd but only in one area , if you can ballast the boat towards the filler then you'll definitely get more of it , sounds to me that it's really not going to be easy at all but it's definitely going to have to be done , TBH it's probably a specialist company job given that it's so difficult to get to , there will be a way but I doubt it cheap .

I'm guessing that there's no way of removing the tank completely as that's by far the easiest way.

 

[ExSurveyor]

When I had a similar problem on the Medway my engineer used a engine oil removal pump to remove diesel starting at the bottom of the tank. He took about 20 litres of crud out before it started to come through clean. Good dose of anti bug and I never had a problem again.

Access was via the filler cap

[smitch6]

nope they put the tanks in the put the top half of the boat onto the bottom half, so not a hope in ..... of getting any of the 3 tanks out without splitting the boat.

but the filler pipe is only 6" long and goes straight into the top middle of the tank, so i may be ok to get a wet vac in there,

the boat has been sitting for about 5 years, tho with the shut off valve in the off position so the diesel could only go to the valve

[Smoggy]

A boat sat for 5 years with fuel in is bound to have a carpet of dead bug, can you get to the top of the tank with a drill and fit a top entry pipe at all? maybe easier in the long run.

I'll bet half the boats that never go to sea have a layer of the same on the bottom but a shorter pickup pipe, if it never gets stirred up you'll never notice it's there.

I had to replace both my tanks a couple of years ago and it was a both engines out job to get to them, not cheap.

[grendel]

lidls had oil pumps for sale a couple of weeks back so you might get lucky, to be honest i wouldnt use a wet and dry vacuum for fuel, as no matter what the motor brushes can arc and mix with the fuel vapor

[annv]

Hi Smitch Turn of fuel tap at tank remove pipe from tap turn tap on to check blockage isn't in tap or bottom of tank go to pump or filter which ever is next get cycle pump and connect to pipe and give it a few sharp pumps this will give you 50/60 psi lot easier than a compressor when clear reconnect if still no suction get a length of hose with a funnel on one end connect to outlet of filter fill funnel with diesel holding it higher then filter if there's a leak you will be able to see where as it will run out of leak.when replacing filter rubber rings smear a little grease on surface this will help to stop rings moving as you do up the bolt. John

[Smoggy]

If cav type filter housings make sure the old seals are out of the groove before fitting the new one, they are bu55ers for lurking in the top of the grove and causing the new seal to deform just enough to let air in, I'm guessing your filters are above the level of the fuel in which case you can have an air leak with no obvious fuel leaks.

Most filters on boats tend to be in awkward places to get a good view of from below which lends itself to the problem.

 

This is the sort of crud I had in the bottom of my tanks before I replaced them.

[OldBerkshireBoy]

2 hours ago, annv said:

When replacing filter rubber rings smear a little grease on surface this will help to stop rings moving as you do up the bolt. John

Some rubber compounds breakdown when some grease compounds are applied, best practice for me is to lubricate the O-rings with what passes through, in this case clean diesel.

[CapitainFrenchy]

Hello,

according to the diameter, internal, a cable or sheath of bicycle brake?

Cdlt