Slow Diesel Leak Part 2

I might have found my diesel leak, but it is not in the upstream fuel lines or filters.

To recap, I have a slow diesel leak. After 6 days at the berth, the paint tray under my Bukh DV10 engine collected about 500ml, which means it is dripping about 80 to 100ml per day, when everything is idle and turned off.

To get better access to my engine, I cut an inspection panel into the dividing wall between the head compartment, on the port side, and the engine compartment - see second photo below. I'll fix up the piece I cut out as a removable panel. It took a while to figure out where to drive my jigsaw, but the worst part was two weeks' ago when I removed some ancient sound insulation that crumbled into an evil black goo that stained everything black and brown. The only way to get it off was acetone (highly toxic volatile liquid in a confined space on a hot day - what could possibly go wrong?)

The new access hole now gives me good access to the port side of the Diesel engine, where the fuel lines connect and where the water impeller sits. I previously marvelled at the insane contortions and blind relocation of bolts needed to remove and refit the impeller. The new access hole makes things much more amenable.

I would also begin to look at what was happening when the engine was running. It needed more bodily contortions, but at least I did not have to suspend my torso over the engine when it was running. These new contortions comprised squeezing into the gap between the toilet and wall, lying on my back and placing legs vertically against the forward dividing wall of the head compartment. Where is that midget spanner monkey when you need him? From there, I could also see one drip per second falling off the rear port-side sump pan bolt head. I now need to find where the fuel is coming from.

I then used my phone to video the engine and various parts when running. I went home and watched the videos on a big screen and found some shiny liquid at the connection between the fuel pump and pressure fuel line - see first screen shot below. I tightened those connections before I left and will check them again tomorrow.

The photos make it look much more spacious than it really is.

So, the next area of investigation is where the two fuel hose connections connect to the fuel pump. The prime suspect is the pressure fuel line. I had previously removed it in my attempts to restart the engine earlier, and maybe I did not tighten it enough when I replaced it. (The engine now starts nicely on the second or third crank). It might be as simple as tightening the nuts.

The process of elimination continues, but I think I'm closing in on the problem.

you need to replace the red ortac fuel hose with proper diesel fuel hose.the red hose is a high temp high presure hose .but notorious for losing its clamping preasure as it will squash out at the hose clamp this will be your leak if you have removed it

+1 replace all hoses and clamps. A good job done well for not a lot of $ will reward you every time you don't have hassles. I like your bravado as to cutting good size inspection hatches, if it's an episode to gain access to do simple maintenance then it won't happen, good on you !

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Achernar said..

grich62 said..
you need to replace the red ortac fuel hose with proper diesel fuel hose.the red hose is a high temp high presure hose .but notorious for losing its clamping preasure as it will squash out at the hose clamp this will be your leak if you have removed it

I checked the red hose yesterday and, as you predicted, it had squashed out at the clamps. I could not get the red hose off the barbs/spigots, which indicates that the hose has deformed at the joints. I'll probably have to cut it off, but I put it back because I need to get a replacement, but will replace it with proper diesel hose. The leak is still leaking, and might have increased to about 200 ml per day, following my attempts to tighten the nuts (which could have loosened the seals on the red hose).

Also, when I took apart the joint fittings, I found something that looking like clear silicon sealant around the copper O rings - see photo below. Am I right in thinking that this is a bodge job, or should I be using some kind of sealing compound?

looks like some attempt at sealing ,copper washers can be heated to cherry red and quenched in water ,this will soften them and make them seal better.be carefull when you tighten the fitting as they can strip out in the housing, use some thread sealant,locktite 515 or577 or similar to help seal the thread,dont use pft tape as it can get to your pump and cause issues.
the red hose will hold on to barbs well so cut them of be carefull not to scratch the barb as this can damage new hose
you are definetly in the right place if it is leaking more

Yep that bit of goo is as bodgy as it gets, you will either have a compression fitting, flared or with a olive on the the pipe or a banjo type arrangement that relies on a copper or fibre washers. Thread sealant on those type of fittings is detrimental to the seal as it limits the force the nut can apply to the olive/washer. Ps my cav filter water separator is plumbed the same way as yours, I doubt I will change it around though as there's no deck fillers to aid the ingestion of water

Hi Arch Well done on the engine access panel. Good thinking.
From your first photo it looks like the high pressure fuel delivery line(A) to the injector is leaking or housing for delivery valve seal (B) is leaking.
In the case of A : the fuel line will have a "banjo" fitting at the injector end and an "olive" compression fitting at the pump end. From the piece of wrapping that you have recovered it would seem that someone has tried to tighten the fitting and failed.
In that case I would think the "olive " compression fitting has had it. If so that means a new high pressure fuel delivery line.
You can make a new line yourself or have it made up. To make it your self is not a difficult or expensive task. You need the same inside and outside diameter tube. The old banjo fitting. You can saw it off, drill out the inlet and soft solder it on to new tube. The compression fitting can be re used but not the olive, so I would suggest hunting down a new nut as well. The tube must be same length as the old one. Once you have the ends on, bend to shape very carefully. You will find youtubes on hand bending fuel line tubes. Fit with new or annealed copper washers.
In the case of B, I would replace the o-ring and washer (indicated in the drawing) while you have everything apart. You don't need genuine Bukh parts for this.
Slowly, carefully and cleanly and it will be a satisfying and educational job.
?Gary

Gary, thanks again for the advice.

if it is still leaking go to a diesel fuel injection shop and buy new copper seal rings, dont buy from shops out of gk kit as the washer is different .also if you do have to take it a part inspect the banjo bolt very carefuly at the holes drilled through the side for elongation or cracking ,this is a sign of over tightening the banjobolts.also a tip is to check in side the banjo bolt for a screen this can be a source of fuel blokage, they have caught many mechanics out

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Ramona said..
Those copper rings are about 10c from an engineering shop. Cost more for the gas to anneal the old ones. When buying hose clips try to get ones that don't have the holes punched through them. OK for the fuel lines in this case but the larger sizes will break regularly. The clamp on the exhaust is the right type. There is a clear plastic hose in your engine room slowly hardening up!

Thanks Ramona, especially the warning about the clear plastic hose. It is the water intake, so gets knocked down the list by the diesel leak, but I see I need to do replace it before it becomes a problem. A previous owner had re-routed the water hose around the front of the engine because the barb on the impeller seems to be at the wrong angle for the engine mounting-blocks, and it was totally inaccessible to hand or eye. Now that I have my nice big access panel, I can get to the connection much more easily, and I can actually see it when I do something to it.

An update on the leak - when I checked this afternoon, the paint tray under the engine had collected about 20 to 30 ML fuel over 24 hours, which is a big improvement on about ten times as much in the same period. I think that most of this came from the filter (the one that screws directly onto the engine block), which I had unintentionally loosened yesterday. So I tightened it up today. It seems difficult to get a good seal between the outer rubber ring on the filter and the alloy filter cover.

I put a paper towel under the engine and ran it for about 5 to 10 minutes, and the towel picked up a couple of drops, which might have come from the lift pump. That's not bad, and it could be some spillage getting shook off the engine, or it could be a genuine leak. I'm looking at the diesel intake hose - the greenish-grey hose in the photo - and wondering if that is the next thing to replace.

There is obviously more than one potential leak, but I am happy that I have reduced it/them to some minor drips.

Update, but not a complete solution, yet.

Checked the boat again, today, after a week. The paint tray under the engine had collected another 100 mL of fuel, so I did some more investigating and attempting to tighten stuff.

This time, I took my really powerful LED Lenser torch. I should have taken it earlier and was using the yellow plastic cheapo torch on board. You need a really powerful torch for day-time working. I ran the engine again, and could see a leak at the connectors at the pressure pump, which is in an awkward location at the back. With the engine running, the drips under the engine increased to about 1 per second. Another thing I should have brought was a socket set, because I was trying to tighten bolds with a large adjustable spanner.

I could not tell if the leak was from the new rubber inlet hose or the old metal-pipe outlet, or the housing. If its the outlet or housing, I might have to resort to Gary's fix-ups. (At least I now have a butane torch for the soldering). I'll return next week with the socket set and powerful torch. I'll also start the internet hunt for parts.

PS Gary, not quite sure if "enjoying" is the right word. It might be if I eventually prevail, but I think "irritated", "sweaty", "dirty" describe my current state better. However, I'll be even dirtier if I have to replace the engine, or if the Admiral refuses to sail because of the whiff diesel swilling around in the bilge, so I will persist. The upside is that I'm learning about Diesel engines, so I don't feel that I'm completely wasting my time.

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samsturdy said..
When I lived in country South Australia I remember an old farmer having a fuel leak on his tractor, he fixed it by loosening the joint and pressing soap into it. I can't remember if it was diesel or petrol though.

That was an old trick for leaking petrol tanks.

Maybe this company?

www.brisbanefuelinjection.com.au/products/banjo-bolts-metric

The stuff is on eBay if you know the thread. Otherwise, any engineering shop that has a Speedflow catalogue. Speed shops, brake repair shops these parts are everywhere.

Gary,

Thanks for the video link. The video makes it look easy, but it must have taken the fellow several weeks. However, it must be immensely satisfying to start it up at the end and hear it purring over. He appears to have two things I don't have; brazing (maybe my butane burner will do the job) and drilling, as in a pillar-drill. I've only got a vice and a hand-drill, or I'd have a go at making my own banjo bolts and copper O rings.

Many years ago, I pulled my 4 cylinder motorcycle engine apart and reassembled it in my back yard. All was fine until I cranked it over. I had not set up the timing right on the cam-shaft and bent all the valve heads, so it would not start. I took it to a proper mechanic to fix it up. Even so, carting the motorcycle engine off to the repair shop was much easier than pulling out a boat Diesel engine, and there are far more motorcycle mechanics than boat diesel mechanics.

ach if you measure the banjo bolt thread a engineering shop will be able to make a barb to suit and remove the faulty banjo .the parts to repair the leak should be available ,ie new bango and bolt from the engine manufactue,fuel pump repair shops normaly sell banjo bolts,the banjo can ofen be relaped with fin sand paper and glass,i have said it before but you must have the corect washers on the banjo as there is often a small lip on the housing around where the banjo seats. another way you can repair this,taking great care is to clean all parts well and apply a smal amount of master gasket to all mating surfaces and both sides of the washers and tighten down and leave to dry. you must only use just enough to give a small coating

What is actually wrong with the banjo bolt and eye? Would a correctly sized Dowty washer on either side instead of the crush washers solve the problem?