Diesel Engine Fuel Pipe Repair

[Sandero]

On my trusty old Volvo Penta MD 17D engine (25 yrs old) the return fuel line to the fuel pump began to leak. The part is no longer available and I obtained one from an older engine (might have been a MD 17C). It doesn't appear to be the exact configuration. But I have to check it when I get out to the boat.

Assuming it's not and not very different, can it be bent to fit and if so how does one do this. I believe it is made from 1/8" copper tubing or the metric equivalent. I have yet to clean it up and attempt any bending pending some advice.

What say you?

The alternative is to remove the broken one and have it professionally repaired (soldered, welded, braised or whatever they do).

[ConradG]

I'm not familiar with the volvo but if it is a return line it is probably low presure. If the fittings are good then hose should work fine. Smooth plastic that takes some heat is better than rubber that can deteriorate (no filter in between unless it is a return to the filter). Used on Mercedes and some Kabotas, If the non fitting tube is in fact copper and can be bent without kinking it should be fine. But if it is that thick walled steel tube beware because it could be high presure, not a return....Are you sure it is the tube that is leaking and not a sealing washer at a banjo or other type fitting?

[shakey doug]

If in fact it is a 17c it will be the same, md series volvo fuel return lines are low pressure. If you have to alter pipe, small changes can be made if done carefully,if pipe is copper larger alterations can be made by annealing pipe . Heat pipe over gas stove or similiar to a crimson colour at point of direction change then quickly dunk in cold water this will soften pipe making it pliable repeat as necessary.

[PieRatPeat]

Sounds like you shouldn't have to make any mods, but on the off-chance that you do, here's an idea I've been meaning to try. I haven't actually done this yet, but have read that if you pack thin walled tubing with fine sand it can be bent without crimping or collapse.

This makes sense to me theoretically. The sand would push back against the wall of the tubing and would I believe be similar in concept to a conduit tube bender (a long spring you put inside electrical conduit to facilitate bending without damage). I suspect it would certainly be worth trying if you were stuck with no other options. You might want to try this on a piece of scrap material, just in case but thought I'd put it out there for folks to try. No guarantees, but let me know if works!

- peterd

[Sandero]

The pipe in question is about 24 inches long and has 3 "ports" which go to each cylinder. That part seems OK. Need to checl. OAL seems OK, but the end which attaches to the fuel pump... where the leak is needs to be bent/twisted to make the faces align. It has some sort of "ferrule" which is where the connections are made.. a donut shape with a double (banjo?) washer... and a shaft where the pipe / tube is welded to. Replacing this means messing about with 4 connections. I've got new washers and it is a low pressure line.

Hose might work for the first part of the run from the fuel pump to the last cylinder. But this means severing the original pipe... to insert the hose... fuel hose which needs to fit over the ferrule at one end (larger diameter) and to the pipe.. smaller diameter... unless I run the hose to the first ferrule on the last cylinder.

I suppose I can take the pipe off and use it for a template for the bends. Is there any other way?

[GordMay]

Google bending installing "hard lines"

ie
Installing & Bending Hard Lines - Tech Articles - Mopar Muscle Magazine

[ConradG]

Be careful not to overtighten bajo bolts if you have one...they crack easily! Been there, done that...

If the jog ampngst injectors fits fine yet you are short (or long) on the injector to pump, filter or where ever it goes, perhaps a cut in the pipe, a section of hose and some hose clamps would be simplest...Low pressure side on many diesels are just little press on tubes between the injectors with no clamps. Measure the od of the steel, copper or whatever it is and see if a fuel hose id can work.

Rinse out well (use diesel) after cutting and I'd stay away from sand in my fuel pump thanks...Careful even pressure over a suitible radius (piece of pipe) should do well for small diameter tube if you want to bend it. The sand thing can help with thin walled larger diameter tube but you really need some heat for it to be effective, allowing the outer material to stretch and the inner material to "upset" or thicken. Then the sand is all baked on the inside and not really suitible to this aplication IMHO.

Stay simple. If it can't be bent a little to be made to fit easily, use the ends as the fittings and hose between them...My Yanmar,3 Mercedes, 2 VW, Allis Chalmers, 3 Cummins, Toyota, Kabota all have hose in various configurations on the low pressur return side. Only the Allis Chalmers has the funky steel link between injectors but then goes to hose to the pump/tank return T. The International is common rail so that's a whole 'nother kettle of fish....