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Old 16-10-2010, 17:52   #1
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Taking It Apart - Fuel System

I discovered a "substantial" fuel leak at the fuel pump on my Volvo MD17D and have managed to locate exactly where it is.

It appears to come from the "joint" where the most aft fuel delivery pipe is connected to the body of the pump. I can't get a wrench in there to tighten it as the ones I have can't turn unless I remove some of the other fuel pipes.

So this looks like I have to dis assemble almost all the pipes to get to the bottom of this... the leaking one...or at least most of them connected to the fuel pump. YUCK

Do I:

simply try to tighten the nut on the leaking pipe assuming it is not tight enough to press the existing alum gasket down and reassemble? (wouldn't that be nice)

take the offending parts (pipe etc.) out and replace only the gasket where the leak was?

replace all the gaskets for all removed fuel pipes?

How tight is tight enough to torque these "compression" fittings? Can they be overtightened?

Is the only means to know if the repair worked is put it all together and run the engine? And if it didn't wash, rinse and repeat?

Is this the type of repair I should let a diesel mechanic do? I have the replacement gaskets? What should I expect to pay for this?
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Old 16-10-2010, 18:23   #2
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I bet Chief Engineer will chime in when he notices this thread. I am a shade tree mechanic but my 2 cents is---You want to kill the problem. Do not re-use gaskets/parts. That is a sure way to end up doing it twice. Analyze the sequence needed to pull it apart without a big spill of fuel. Lay out your tools and dive right in there. Hopefully you only have a leaky connection and not a worn out pump telling you it needs replaced with a calibrated leak.

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Old 16-10-2010, 19:42   #3
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If it's as difficult as you indicate, then I'd replace all the gaskets/crush washers, check all the piping, and carefully reassemble.
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Old 16-10-2010, 19:45   #4
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Would a crow foot wrench work? I don't have any experience with them but they look so cool. Grip-On Tools JUMBO Crowfoot Wrenches — 1/2in. Drive, 14-Pc. Set | Crowfoot | Northern Tool + Equipment
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Old 16-10-2010, 19:47   #5
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For nearly any repair it's almost always worth the time to strip away the bad stuff and repair it correctly. Often I spend more time trying to figure out a way to save time than if I just started on it. The only way you're not wasting time is if you're doing your home work and ordering the parts for what you'll end up needing to do the project and planning out the steps.

Might be a stupid question but why not just use rubber hose?
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Old 17-10-2010, 12:37   #6
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Take everything apart. Replace the crushwashers.....Better to do a complet job than 1/2 way. Do not overtighten
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Old 17-10-2010, 13:34   #7
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Thanks guys,

Those wrenches don't help - sorry.

The pipes are not leaking.

I suppose it's a "crush washer" and depending on how many of the pipes I need to get off I could be in for maybe as many 14 of them if all the pipes are taken off, though I might not have to do the first two cylinders.

They are cheap and I have a half dozen of so and can order more. I think that's the only possible failed part.

But should I assume the similar ones at the other pipe/connections will fail soon (25yr old engine) and just replace them as well? I suppose this may be required if I can't "reuse" any of them.

I report back as I intend to tackle this in 2 weeks when I move from the mooring to the in water winter storage.
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Old 17-10-2010, 16:09   #8
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Before you pull everything apart, try to make or modify a spanner and check the tightness of the leaking union. Maybe a split box or split and reinforced ring or even one of the split flare nut spanners may work. Regards, Richard.
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Old 17-10-2010, 18:47   #9
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If they are aluminum or aluminium.....you probably cannot heat them like the copper washers.
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Old 17-10-2010, 19:08   #10
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I attached the fuel system schematic here.

If I read you right you are talking about the flare fitting coming from the injector pump.

There is no washer here. It is a flare fitting. The worst case is the fitting got over tightened and the nut split.

I think in you case your will have to take apart all the spacers that separate and support the three tubes (items 22 etc, etc) to get access.

While I only have 2 cylinders, I have a similar access problem. What I do is install the aft one first then the forward one.

Here is a link to that schematic.

Volvo Penta Schematic Part Diagrams
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Old 17-10-2010, 21:28   #11
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Ex Cal,

I have the drawings! Actually there is another one which shows the the parts inside the pump. BUT... in the drawing that you attached... if you look at the pump itself you see three threaded connectors which the pipes are then connected to. Those three threaded connectors are part of the assembly inside the pump and it where the leak is coming from... exactly where the last of those three meets the pump housing. I believe that there is a gasket under each one of those.

So I can remove the pipes, which ARE flare fittings, but that is ABOVE where the leak is.

So I literally need to take part of the pump apart or remove those threaded "things" and replace the gasket which I recall was #18 on the exploded diagram I had.

The leaking part seems to be a knurled cylinder threaded to engage the pump case (tightened on a gasket) with a hex top to tighten it and then it must have the flare connector on top to receive the pipe. I can't explain this any better. I apologize.

I could try to grind the cheeks of an open ended wrench or cut a slit in a box wrench to slip over the pipe and then down on the hex part. It's 13mm if I recall and it's worth a try. Box wrenches are smaller than open ended wrenches.

Here is a photo the leaking part. Notice the tape on a pipe which I thought was leaking. It's not that one. It's below the knurled piece. Notice how there is no room to get a wrench in there and tighten anything. I might be able to tighten if I remove the larger pipe in front coming from the fuel filter.
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Old 17-10-2010, 21:57   #12
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Ok - I wanted to be sure. Pictures = 1k words.

Yup - I would pull both banjo fittings. Right and left.

As for the assembly under the flare fitting - Based on your comment I guess you have the schematic for the pump. It's interesting in there with springs etc...

And yes, my schematic shows it as item 18 as well.
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Old 18-10-2010, 03:10   #13
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Ex-Calif,

Thanks again for confirming my hunches. I will have a go at this in a few weeks and report back. Removing the parts left and right means taking them off completely as the pipes are rigid. So it's a min 4 banjos to replace. And at least the one to the first cylinder.

The picture explains it all pretty well.

I don't have a clue how that pump works.
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Old 05-12-2010, 09:40   #14
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I finally put the boat in in-water winter storage and took the fuel system apart to get at the leak. I had to remove one entire fuel pipe to be able to turn a wrench on the suspect inject pump "fitting" (don't know the word for the part).

I got everything apart after carefully cleaning that area and set apart the parts and took pix as I proceeded.

When I got to the suspect o-ring it was clearly deformed and seemed to be lying over the threads and not in the groove meant for it. Hmmm That looked very suspicious. I had sent for the part but the Volvo people sent the aluminum pressure gaskets/seals and so I had to get the 15mm O ring. I sent a photo of the assembly with the faulty o ring on top of the parts diagram with a notation and arrow showing the part needed - two days later it arrived - $2.50 per o ring. I ordered 3 spares and then set about to put it back together using new aluminum gaskets. Getting the pipes on in some cases was much harder then getting them off, but after struggling with alignment I got it all done. I then proceeded to clean up the bilge and before bleeding and firing the engine and I discovered a spring that had fallen out from the pump assembly. Oh Piss!. I unassembled the whole thing, inserted and was about to insert the spring and checked the blow up diagram and noticed there was a tiny washer (you can see it part #24 with part # 23 at the top of the spring part # 16. YIKES where was that? It wasn't in the bilge. I took a magnifying glass and a very bright light and peered into the pump and saw the bugger on its edge laying where the threads would engage. Getting it out was a bitch because it was so tiny - perhaps 3mm in diameter at most and very thin. I got it out with a tiny screw driver and it was undamaged.

I then assembled all the parts once again, bled the air from the system and then cranked the engine. It had been sitting unused for a month and more than a week with the fuel pump and pipes unassembled.

It shot out a healthy amount of gray.. even black smoke and then compression kicked in and it was off and running. Down I went with a high intensity light to look for leaks.

No leaks. I let the engine run for a half hour to get it up to normal operating temps. The air temps were in the low 40s. No sign of leaks at all.

Mission accomplished.

It took a few hours to take apart and clean up, and a bit more to put it back together, plus all the research and fretting - lets call it a day.

I suspect I had been running on less than 3 cylinders because of the fuel problem. Engine sounds fine now and she is winterized.

More projects on the list await.
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Old 05-12-2010, 15:43   #15
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I suppose it's a "crush washer" and depending on how many of the pipes I need to get off I could be in for maybe as many 14 of them if all the pipes are taken off, though I might not have to do the first two cylinders.
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