Wednesday 2nd October 2013 - Miserable

Living in the UK at anchor with a dog and a toddler - what can possibly go wrong?!
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Jeff
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Wednesday 2nd October 2013 - Miserable

Post by Jeff »

Bit miserable here. Very miserable weather, still got air getting in the fuel somehow, and I've found that there definitely is fuel getting in to the oil (you may recall my comments about possible oil level rising issue).

I'm at my wits end with the air in the fuel thing. I've replaced about everything now. Sometimes it's flawless and gets no air in it for 24 hours. And just when I think I've sussed it, air again.

I've got one key symptom which I think proves the issue is in the final section, the injector pump, of the fuel system... that is that the air is always only manifest at the final bleed screw. It only appears after a period of not using the engine - and the engine always runs fine once started - and always starts up easily within 6 hours of a previous run. The final hose leading to the injector pump goes down and then up in a large U so any air leak before it would appear in a different place to that noted.

So it then can only be:

1. One of the bleed screws
I have installed brand new copper washers on cleaned up surfaces and made them nice and tight. I've re-done this a couple of times.

2. The final hose connection to the injector pump.
I've re-made this connection a few times and applied Loctite sealant.

3. The pipe's connection to the connector that attaches to the injector pump.
This is a brand new connection made up by Pirtek. Regardless I've added sealant to it, just in case.

4. Something leaking into the injector pump itself.
Unsure how likely this is. Seems rather unlikely.


On reflection I am drawn to look again at the Pirtek hose. We had no problem with air leaks before I replaced it, and the guy used the old connectors on a new hose, and the previously round copper pipe he crimped onto was deformed slightly in the crimping process. Will be annoying to have to go back to Pirtek but to eliminate it completely perhaps that's worth doing.

Anyone know how likely option 4 is though? Is it worth taking the injector pump apart and checking gaskets?

I did wonder if it could be related to the leaking of fuel into the oil from the fuel return line (which I've now witnessed slowly oozing from the final banjo connection where the final injector leads to the fuel return... but if it was there, air would not back up to the injector pump... and as we've had that problem for 2 years now - without the air leak issue - I think they're separate problems.

On the bright side:

Found a new up-river anchorage.

Got dragged around the main town anchorage one night by a dolphin scratching itself on our anchor chain (Nina loved this)

Had lots of seal encounters.

Enjoyed a visit by my parents and the tourist boat trip to Totnes and back.

The stove is keeping us all very warm, dry and toasty.

And the forecast for the weekend looks good!
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evenkeel
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Post by evenkeel »

Hi Jeff
i dont know much about the injector pump but i know they are expensive beasts to have repaired so i wouldnt undertake taking it apart unless you know for certain thats the problem. If its possible and you still have the old connectors and fuel lines could you fit a non return valve in the last line before the injector pump. The only other thought i have is to bypass all fuel pipes, and run a rubber pipe from fuel tank to fuel pump through an inline filter and then another from fuel pump to injector pump. that way you can eliminate all the connectors, if that works, you can work your way back until you find the cause.
only suggestions but hopefully with the many heads on here, others will have their own ideas and the cause will be found.
Discus
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Post by Discus »

Doesn't sound good. I'm with evenkeel with the injector pump - they are not user serviceable and need some fairly precise setting up that usually means specialist tools. It is also the most expensive option on the list so should be considered last. (If you need to, you can get them reconditioned). Old connectors on a new hose? Not on your life! The connectors should have been changed, I am surprised Pirtek did not insist on this. The fuel leak is annoying but much more fixable. We had the same thing at the same place on our engine at the start of the season. Whoever designed banjo bolts should be put up against a wall!!! Check to see if the leak is from the banjo or the crimped bit (assuming they have a crimped end). Of course, it was a bit easier for us as our lines run external to the rocker cover. Am I correct in assuming that your fuel tank is below the engine? I just wonder if the lift pump is struggling to maintain positive pressure in the lines running to the filters. In addition, can I ask if you have diesel heating, and if so, is the fuel take off from the engine filters? This has been known to cause the issues you describe as the heating should always have its own tank supply. Your instincts serve you well with regards to the hose. Start there. Sorry you are still having these issues BTW. These things are sent to try us!

Good luck

Rob :batman:
Jeff
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Post by Jeff »

Thanks for the ideas. I will leave the injector pump alone!

Evenkeel. The air only appears at the last bleed screw on the injector pump after a period of not being in use. If I leave the engine alone for 24 hours, then bleed before starting, the air is there and only there and the engine starts no problem... So I think I can therefore only conclude the air is getting in somewhere at the injector pump as the pipe before that does a large 'U'.

Rob. Eberspacher take-off is direct from the tank with its own inline filter. Completely different system. Pirtek replaced all of our hoses in this way, using the old connectors, but only this one ended up being deformed, and only this one is left using the original brass olive and 90 degree elbow.

I took it off again and looked it over. It looks fine tbh. I re installed it again with much care and loctite.

Fuel return line banjo has no crimped part from which to leak :(


As the fuel leak into the oil is minuscule, and the.engine runs fine indefinitely once started, do you agree with me that its safe to use the boat at sea while still suffering from these minor niggles?

If so, we could make it to Plymouth, and go back to Pirtek!
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Jeff
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Post by Jeff »

Oh and the tanks are alongside the engine, and full. I guess when very low there'd be a bit of work to do but it worked fine when they were very nearly empty when we first bought the boat. When using the lift pump handle to bleed the air, fuel is happy to spurt out with much gusto.
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Discus
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Post by Discus »

Well, having spent my student summers installing refrigeration equipment, we were told never to reuse olives as if they had been over tightened previously then they were lightly to leak and cause the compressors to eventually trip out on low pressure. This is sounding like a likely candidate. I can't believe how frustrating this must all be for you. You just expect the damn thing to work. Being as the problem only arises when starting the engine from cold then you should be fine to get to Plymouth. Our current engine issue is the opposite as the mounts are shot, I think it is misaligned with the shaft and periodically makes a bit of a grinding noise especially above 2000rpm. Fortunately we are coming out on the 21st so new mounts can go in - although how I am going to jack up a 285kg engine is a bit of a stumper!

Will cogitate further on your issue. Bit of a head scratcher really. :shaking:

Rob
Terry T
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Post by Terry T »

Jeff I'd advise to get your fuel leak sorted ASAP not wanting to scarce monger but if you have diesel /vapour in the sump you could have a runaway engine by being fueled thro valve guides or pistons. Prob not likely but a possibility .

look forward to seeing you all at Plymouth if you can make it.
Last edited by Terry T on Wed Oct 02, 2013 8:17 pm, edited 1 time in total.
evenkeel
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Post by evenkeel »

if the fitting to the injector pump is a banjo fitting try temporary using fibre washers instead of the copper ones as they can seal on uneven surfaces better, also make sure the bolt on the banjo is the right length, when i changed some fittings a while ago on a digger, the new banjo was slightly thicker and the hole in the bolt didnt quite line up, although in my case this caused the engine to scavenge for fuel when fully revved not as in you case an air leak but its worth checking. The other thought is if you have hade replacements made, make sure they have given you like for like, not imperial instead of metric or vice versa.
will keep thinking, it helps keep the grey matter young!!!
Jeff
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Post by Jeff »

Thanks for all the replies and thoughts.

Evenkeel, your fibre washer suggestion won't be useful for the injector pump connection as that's the one with the olive - but it might be worth a try on the final banjo on the fuel return line. The replacement screw I used in there appeared to be the same thread spacing as the old one, but was definitely quite a bit harder to wind in - hope I've not added to my woes there. The old one just had a slot up the length of it. The new one is hollow, with a hole out of the side. Take your point re importance of length but tests so far seem OK - engine runs fine - so I guess that means it must be letting out enough fuel to the banjo.

Meanwhile, I started the engine this AM after a 15 hour shutdown. It started instantly. No air. I'd done two things yesterday:

1. After running the engine I turned off the fuel completely at the primary filter - so reducing any suction that might result over time due to fuel trying to pull back down into the (perhaps) slightly lower pressure head of the tank.

2. I removed and re-seated the final hose connection to the injector pump.

Very pessimistic as we've had 24 hour shutdowns followed by instant start in the past, then subsequent air, but there's a slim chance it might be OK now. If so then I reckon we've had air getting in at both bleed screws AND the final hose connection - the fuel system was practically porous!

Off to see if I can find a local supplier of fibre washers...
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Post by Jeff »

I'll make a new blog post about this with pics and a video.... but... this am the engine started instantly after 15 hours downtime... and I fiddled with my last banjo (the engine fuel line return, nothing dodgy!) And it dawned on me that the leak was from the union between the fuel 'rail' and the banjo... perhaps as per your suggestion rob about the crimp? Anyway after lamenting about the work required to remove the whole thing and replace or sort it I remembered a trick I learned from my first boat a few years ago... liquid metal! I know it's a bit of a bodge but a quick row and £7 later... our engine is not leaking diesel into the sump any more!

Proper post hopefully tomorrow if I get time after working out how to use an EEPROM emulator for some programming I have to do for work...

Unsure about fuel air thing but definitely less miserable atm.
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Discus
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Post by Discus »

I will keep my fingers crossed for you!!! :thumleft: EEPROM emulator??? Sounds too technical, my head is already hurting :?
Jeff
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Post by Jeff »

Mine too!
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