Volvo MD22L-B fuel dripping from air intake

[jssailem]

See if you can find someone scraping out an old engine. That is how I got replacement steel high pressure fuel lines. $10 a piece.

Ralph is correct. Return lines are low pressure and need not be steel. The suggestion of having some made means finding a willing shop. I tried that with my lines and was unsuccessful. Granted the lines I was working on were high pressure.

I wonder if brake lines could be modified to serve your purpose.

 

[Hayden Watson]

See if you can find someone scraping out an old engine. That is how I got replacement steel high pressure fuel lines. $10 a piece.

Ralph is correct. Return lines are low pressure and need not be steel. The suggestion of having some made means finding a willing shop. I tried that with my lines and was unsuccessful. Granted the lines I was working on were high pressure.

I wonder if brake lines could be modified to serve your purpose.

Brake lines would be good if you can find them with the correct ends but most that I am familiar with have flared compression ends not ferule compression ends.
Given that the return lines should be low pressure, you could probably fabricate them from type K annealed copper tubing which is easily hand bendable using a bending spring.

 

[Hayden Watson]

One other possibility is to anneal the current ferrule so that it is soft again. The ferrules start life as annealed copper which is very soft but work hardens quickly. That is why they will seal the first time you tighten them but not the second.
This should work if the tube is steel and the ferrule is copper. You can anneal the copper ferrule in place because the annealing temperatrue of copper is too cool to affect the steel tubing.

 

[jibes138]

Can you just get a new ferrule?

 

[jibes138]

They make tape to stop leaks in radiator hoses available at auto stores. If it can handle hot antifreeze it might be ok for fuel. Then put a hose clamp over it for piece of mind. Might last five years. Otherwise ask an auto parts guy if they have anything specifically for fuel. Last resort might be to use a little fuel resistant sealing compound on the joint and let it cure but don’t use too much that flow would be restricted.

 

[Ralph Johnstone]

Having looked at your explanation and picture of the leak, I'm not going to argue why the return lines are steel but accept the fact that they are now steel and going to remain steel. The lines that you do show leading to the leak definitely appear to be in excellent shape :

The simplest and only solution is going to be to seal the leak FROM THE INSIDE of the compression fitting..

This is what you are presently dealing with. Ignore the paste as it's the only pic I could find :

The trick is to find a sealant which will not be affected by the diesel fuel. One possibly good combination would be teflon tape and Permatex #2

Star by cleaning the joint as clean as you can get it with solvent followed by alcohol. Below is what you would do with the wrap of teflon tape always in a CCW direction. Next wipe the tape with a light layer of Permatex going in a CCW direction :

Slide the nut back over the ferrule and tighten. The tape seals any large leaks while the Permatex seals microscopic leaks. Combined together, they are the industrial standard for petroleum NPT fittings.

Sounds fantastic from a theoretical point of view. Let us know how it works in real life.

 

[smokey73]

@Ralph Johnstone Interesting approach. Seems like it might work. Are you saying that this is the way petroleum NPT fittings are made up from the initial assembly, not just as an approach to stopping a leak?

 

[Ralph Johnstone]

Are you saying that this is the way petroleum NPT fittings are made up from the initial assembly,

In refineries, I've seen that garden variety NPT pipe fittings are assembled with a few wraps of teflon tape and then covered with a thin later of a non hardening sealant such as Permatex #2 or some form of teflon paste. The addition of a paste sealant has pretty well becoming an accepted practice as people in the field realize that teflon tape is not a very good thread sealant. Particularly on cold water. It's just neat and tidy. With both tape and sealant, you have less sealant floating around making a mess and both together make a pair with 0% leakage. The joint can also be unscrewed many years down the road.

 

[Rich Stidger]

Thanks @Ralph Johnstone for the info and idea. My hope is that the wrapped temp fix will suffice for this season and I can do something more permanent before layup.

 

[Ralph Johnstone]

My hope is that the wrapped temp fix will suffice for this season

When you get it to seal (and providing there are no cracks) this will be more permanent than any other tubing seal on your engine. No other compression joint has sealant in it and MAY still start to leak sometime in the future. I would not consider doing any further work on it because the best a new tube could do would be to match it. After all, it's atmospheric pressure at best.

 

[SycloneDriver]

Are you sure copper ferrules are used? I have worked on several diesels (John Deere & Cummins) that use a rubbber gasket instead. If the old ferrule can be removed, maybe a rubber gasket could be substituted. I think I have one in my work truck, would you like a picture? They can be purchased at tractor or diesel shops.

 

[smokey73]

@Ralph Johnstone I think Rich is talking about his "tape" over the joint as the wrapped temp fix, not the teflon tape/sealant applied directly to the ferrule.

With the teflon/tape and Permatex #2 how do you tighten the nut? (your post 46) The standard/recommended procedure to tighten a ferrule fitting is to do it by "turns" rather than torque. In other words, for a certain size of tubing with a ferrule fitting, you tighten the nut a certain number of turns (say 1 1/4 turns)and use a "go/no-go tool to confirm. Overtightening is often the cause of a leak for this type of a fitting. I would seem using the tape may change the number of turns? Just asking. From

Distance vs. Torque
Typically the procedure for tightening a compression fitting is specified using the rotation of the nut as the key metric, rather than torque. Compression nuts are threaded, meaning that the number of rotations of the nut is directly correlated to the linear compression of the ferrule, based on the thread’s pitch. Torque, on the other hand, can vary greatly, depending on fitting and ferrule material, lubrication, degree of galling (for stainless fittings), and other factors.

Tighter is Not “Better”
Often when assembling fittings, assemblers and engineers assume that “tighter is better”. This does not hold true for compression fittings. As described in the “Ferrules” section above, the optimal seal is created by a line contact between the ferrule and the tubing. Insufficient tightening of the compression nut will not deform the ferrule enough to create this contact, but over-tightening will deform the ferrule too much, creating a surface contact. A surface contact weakens the seal and often results in leaks

 

[Ralph Johnstone]

I think Rich is talking about his "tape" over the joint as the wrapped temp fix, not the teflon tape/sealant applied directly to the ferrule.

@Rich Stidger , post #46 is a PERMANENT REPAIR for the leak under the nut. The tape and Permatex will be forced into the microscopic crevice which is currently causing the leak. No further repairs are required.

With the teflon/tape and Permatex #2 how do you tighten the nut?

The copper ferrule has already been tightened once around the steel tube by someone counting the required nut rotations (the number varies with the manufacturer of the fitting). The joint will be disassembled, sealants applied, and then reassembled back to its ORIGINAL TIGHTNESS by feel. The sealant inside is soft and pliable and will conform to the interior of the nut and exterior of the ferrule. Where the nut contacts the ferrule, the thickness of the combined sealant will be 0.000". Any areas around the contact that are open will be sealed with the tape and Permatex mixture. Don't make the film of Permatex too thick or some of it may get forced back into the steel tube. Still not a problem.

Gentlemen, this repair is just as simple as it sounds. Sealant being forced into microscopic crevices stopping the leak. The higher the pressure applied, the deeper the sealant is forced into the leaking crevice and the better the seal.

If adhesive tape is applied on the outside of the nut, the greater the force, the more the sealant is pushed away from the leak.

 

[smokey73]

@Ralph Johnstone Sorry, I misunderstood your post. The teflon tape/sealant around the ferrule method you descrilbed in your post #46 is a permanent "repair" when a leak has developed, not an initial installation technique used in the petrochemical industry for ferrule type fittings. I see that when you said it is a used in NPT fittings, which I missed in the original post. I do the same thing when I assemble NPT fittings.

It is a great idea and will keep that repair idea and supplies in my toolbox. I asked about the installation torque or turns and your answer above makes perfect sense. If I undersand it, you'd tighten it to the original tightness by feel or the original recommended number of turns after hand tight. I guess if it doesn't stop the leak, you could tighten it a little more in small increments until the leaks stops. What do you have to lose, it was already leaking? If you can get it to stop that way then leave it as that then becomes a permenant fix unless something else happens to disturb the joint. Is that correct?

 

[JamesG161]

I keep this rescue repair tape on the boat and car.

Amazon.com



Jim...

PS: I can be a permanent fix too.

 

[Ralph Johnstone]

If you can get it to stop that way then leave it as that then becomes a permenant fix unless something else happens to disturb the joint. Is that correct?

If one were truly OCD, and I often feel that way but never diagnosed (yet), one would insert sealant into every tube compression fitting on their engine. The fitting is designed to make a perfect metal to metal contact on the annealed copper ferrule. If that were to fail at any time in the future due to vibration or heat/cool cycling, the flexible sealant would be there to seal off any microscopic pathway to the exterior of the fitting.

I can see it now, all winter long, cut fingers, gashed knuckles, and a dislocated back .................. but they will never, ever, leak as long as the engine exists .

 

[Rich Stidger]

@Ralph Johnstone , I am going to implement your fix in post #46. Question- being uneducated a short while ago as to the correct tightening of these compression joints, I attempted to stop the leak by tightening almost a1/4 T. Do you think I have damaged the joint beyond repair or will your solution still work? I'm looking for an educated opinion.

 

[Ralph Johnstone]

I'm looking for an educated opinion.

Being a graduate of "The School of Hard Knocks", I is the man you wants.

I doubt you've destroyed the internals of the joint with 1/4 turn, but your best indication will be when you take the fitting apart. I would suspect the ferrule has taken the most deformation being the softest part, but as long as it's still smooth on the surface you shouldn't have any problems. Look to see if there's any major deformation of the steel tube under the ferrule and, if it's still reasonably uniform in OD, you're off to the races.

Just out of curiosity, any chance you could supply a closeup photo of the ferrule on the tube ? Enquiring minds and that sort of thing, you know ?

 

[Rich Stidger]

Just out of curiosity, any chance you could supply a closeup photo of the ferrule on the tube ? Enquiring minds and that sort of thing, you know ?

I will when I do the job. It will be a couple weeks at least. Unless of course my tape-wrapped cluge starts gushing......

 

[smokey73]

Looking forward to the post once you get around to trying the fix @Ralph Johnstone has suggested. There is alway room for jello, I mean another way to skin the cat. So once you get to a point where have time to try the fix please let us know the results. I can't see as you have anything to lose in trying it.