How do i find air leak in diesel line

[bugs]

My md2020 has been slow to start since last year's filter changes. It started immediatelyprior to the change. I reseated the filters without success and hoped that this seasons new filters and rings would solve the problem but alas.

The tank is below the engine.
The water trap/1st filter is the highest point and seem ok. When i remove the bleed screw fuel pours out (especially if i glance away!).
The second filter may be the issue, when I use the priming pump i get fuel to squirt out. Ive loosened the injectors and get fuel to come out.
It takes a lot of turning over to get going.
Once running it restarts immediately after a short shutdown period but after a day or so it becomes very difficult again.
Is there a way of finding where the leak may be. I have one copper washer i want to replace onm secondary filter (i am aware of annealing but it is scraped) which may help.
Might it be an injector problem?
Im pretty sure the glow plugs are ok.

in frustration!
h

 

[dukes4monny]

Have you checked for voltage at the glowplugs? Make sure a wire hasn't been knocked off or that they aren't shorting out somehow.
If you are suspicious of any seals / washers I would replace them before digging too deep looking for the cause.
I'm not familiar with that motor, but could you possibly temporarily bypass the secondary filter to see if things improve?

 

[phild501]

I’m no expert, but having spent most of Saturday trying to start, diagnose and then bleed air out of the fuel line of my very slow starting KAD32 you have my sympathy.

I eventually found a miniscule fuel drip from the underside of the banjo connection at the pump. After tightening, I vented the fine filter and hand pumped for about a minute, then loosened off the delivery line nuts and cranked the engine on full throttle (use plenty of kitchen roll!) Engine then started on the touch of the key.

So just guessing but if you’ve got an air leak on the system, you might be able to spot the damp patch/possible drip using a bright torch?

Alternatively could it be cr*p in your fuel? If an injector is partly blocked fuel will not spray into the cylinder properly and cause hard starting. Again just guessing, but this would probably affect it all the time?

 

[wotayottie]

No doubt there is a mechanics trick to make this job easier, but I dont know it. Faced with the same problem I cleaned and remade every joint from the tank to the lift pump. That didnt work so I then taped up each joint with insulating tape and that cured the problem. Taking off that tape at one joint per day soon showed which one it was that was leaking. In fact it was the CAV filter (which our tame diesel expert pointed out was designed to work on the pressure side not the suction side). Took some efforts to cure it.

 

[harvey]

I have heard someone give the advice that to find the leak you should pressurise the system by using a inflatable boat pump into the fuel tank filler hole and then look for the drip of diesel along your fuel line. I can imagine all sorts of difficulties in getting a seal at the filler but there we are.
Good luck
John

 

[oldharry]

To find diesel trace leaks, clean off everything thoroughly, then use coloured tissue paper - Tescos best pink (or any colour) loo roll does nicely, or surplus christmas paper napkins in green or blue:

Any trace of diesel will darken the tissue paper revealing the presence of diesel - or indeed any fluid, including seawater. There is a 'proper' engineers blue soft wipe which does as well, but at several times the price of a loo roll! - and not quite the Andrex touch for the rest of the roll.... !