Leaking fuel line

[jeffhuey1n]

Went to the local Christmas parade. I started out as #1 and went then entire route, collecting toys for Toys For Tots. Not sure how many toys we gathered but we got some. Super danged cold . 18 degrees Fahrenheit cold. Anyway, reached the end of the parade and delivered the toys to the local school facility we use. Getting out of the truck, was hit by a wave of diesel fumes! Looked underneath and fuel was pouring out from somewhere underneath. There was so much spray we couldn’t find the exact leak in the poor lighting at the parking lot next door. Talked it over with Hendersonj and I decided to make a thunder run home. Not one of my best decisions but it worked out, pulled into my driveway and shut it down. Couldn’t work on it Sunday. Along with the run home, I had a battery acting up, which just didn’t want to stay fixed. Then to boot it all the way to the finish line, I had a sewer problem that took hours to get fixed. Got one hour sleep. So Sunday was sleepy time. Got out to the truck about noon today and ended up pulling the heater box out of the way. One of the nylon(?) fuel lines from the secondary fuel filters to the hydraulic head(?) was whizzing diesel all over the place. After much cussing I got the line out and now I get to figure out a fix .

 

[Mullaney]

Went to the local Christmas parade. I started out as #1 and went then entire route, collecting toys for Toys For Tots. Not sure how many toys we gathered but we got some. Super danged cold . 18 degrees Fahrenheit cold. Anyway, reached the end of the parade and delivered the toys to the local school facility we use. Getting out of the truck, was hit by a wave of diesel fumes! Looked underneath and fuel was pouring out from somewhere underneath. There was so much spray we couldn’t find the exact leak in the poor lighting at the parking lot next door. Talked it over with Hendersonj and I decided to make a thunder run home. Not one of my best decisions but it worked out, pulled into my driveway and shut it down. Couldn’t work on it Sunday. Along with the run home, I had a battery acting up, which just didn’t want to stay fixed. Then to boot it all the way to the finish line, I had a sewer problem that took hours to get fixed. Got one hour sleep. So Sunday was sleepy time. Got out to the truck about noon today and ended up pulling the heater box out of the way. One of the nylon(?) fuel lines from the secondary fuel filters to the hydraulic head(?) was whizzing diesel all over the place. After much cussing I got the line out and now I get to figure out a fix .

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Well... At least you got her home under her own power.

 

[jeffhuey1n]

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Well... At least you got her home under her own power.

Yes indeed. Sometimes St Murphy takes mercy.

 

[HDN]

I'm glad you made it home safely and didn't have any fires!

This reminds me of one time I drove my dad's 1953 M37 to a car show in the summer. When I got there, I saw that the side panel between the hood and the fender was wet. Turns out it was spraying gasoline the entire drive there through a leak in the hose! The ethanol-gas blend we've been putting in it up to that point ate the rubber fuel line. I was super lucky that the truck didn't burn up on the 2-mile trip there

That was when we decided all our rubber fuel line was being replaced with rubber barrier line and we were using non-ethanol gas moving forward.

Regarding your fuel line - did your truck come like that? I believe clear hoses of certain materials will degrade when in contact with diesel, turning yellow in color and getting brittle. I believe nylon can safely be used with diesel.

 

[SCSG-G4]

I remember having to temporarily fix one of those lines on a deuce because the two 'nylon' lines had rubbed together and one wore through first (not my truck). Temp fix was to put some rubber hose over the bad part with the slit on the opposite side, then use a number of hose clamps to 'seal' each line, middle clamp directly over the rub point and additional clamps touching it on both sides. Five inches of rubber line and six hose clamps later, no leaks!

 

[87cr250r]

Nylon may have questionable compatibility with some diesel fuels.

Analysis of the Deterioration of Nylon-66 Immersed in GTL Diesel Fuel Part 1. Analysis and Test of Nylon and GTL Diesel Fuel Before and After Immersion

The effect of GTL diesel fuel on organic materials used in fuel delivery systems of vehicles was investigated. Specimens made from 16 kinds of organic materials were immersed in GTL diesel fuels synthesized at Refinery-A and Refinery-B (referred to as GTL-A and GTL-B, respectively) and then subject

www.sae.org

I don't know what diameter you're working with but this stuff resist just about every fuel at all temperatures and in sunlight.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

Use tube supports as it does take compression set when used with compression fittings or Parker Vibralok fittings.

This will still require protection from abrasion. You can always install rubber sleeves over damage prone sections of tubing.

 

[Floridianson]

Myself Napa and Synflex line and one 90* Synflex fitting for final filter and one 45* fitting for the Head. They even make push lock fittings if you want to pay the price.

 

[jeffhuey1n]

I'm glad you made it home safely and didn't have any fires!

This reminds me of one time I drove my dad's 1953 M37 to a car show in the summer. When I got there, I saw that the side panel between the hood and the fender was wet. Turns out it was spraying gasoline the entire drive there through a leak in the hose! The ethanol-gas blend we've been putting in it up to that point ate the rubber fuel line. I was super lucky that the truck didn't burn up on the 2-mile trip there

That was when we decided all our rubber fuel line was being replaced with rubber barrier line and we were using non-ethanol gas moving forward.

Regarding your fuel line - did your truck come like that? I believe clear hoses of certain materials will degrade when in contact with diesel, turning yellow in color and getting brittle. I believe nylon can safely be used with diesel.

All of the fuel lines on this truck are made of an opaque plastic like material. They’ve been on the truck as long as I’ve had it, approximately 15 years. There’s no yellowing although they were painted OD green.

 

[jeffhuey1n]

Nylon may have questionable compatibility with some diesel fuels.

Analysis of the Deterioration of Nylon-66 Immersed in GTL Diesel Fuel Part 1. Analysis and Test of Nylon and GTL Diesel Fuel Before and After Immersion

The effect of GTL diesel fuel on organic materials used in fuel delivery systems of vehicles was investigated. Specimens made from 16 kinds of organic materials were immersed in GTL diesel fuels synthesized at Refinery-A and Refinery-B (referred to as GTL-A and GTL-B, respectively) and then subject

www.sae.org

I don't know what diameter you're working with but this stuff resist just about every fuel at all temperatures and in sunlight.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

Use tube supports as it does take compression set when used with compression fittings or Parker Vibralok fittings.

This will still require protection from abrasion. You can always install rubber sleeves over damage prone sections of tubing.

Thank you for the information. I’ll keep a lookout for the line. I think it’s 3/8 inch. Not sure what the lines are made of. This one probably could have lasted for years longer had I noticed the chafing on the line. Unfortunately, that spot on the line is hidden by the heater assembly. From the top, it’s not visible. The only way I could get at it was disconnect the heater box and rest it on top of the engine. I’ll be checking the rest of my trucks one it gets a bit warmer.

 

[jeffhuey1n]

I remember having to temporarily fix one of those lines on a deuce because the two 'nylon' lines had rubbed together and one wore through first (not my truck). Temp fix was to put some rubber hose over the bad part with the slit on the opposite side, then use a number of hose clamps to 'seal' each line, middle clamp directly over the rub point and additional clamps touching it on both sides. Five inches of rubber line and six hose clamps later, no leaks!

I bought a length of nylon type hose from NAPA. It had similar dimensions as the original. I also bought new compression doohickeys (not sure what they’re called) and inserts to prevent the line from being crushed. None of that worked. There is a slight difference between the original and civilian versions. I dug through my immense stash of parts and came up with a compression splice. It’s a multi piece brass fitting. I cut out the bad piece, about an inch, and installed it. After test fitting, I loosened up one side of the splice so I could get the line aligned with the fitting on each end. Installed everything including the clamp and then turned on the master power. No leaks. By then the sun was going down and it was getting really cold. I’ll need some abrasion pads to protect the line from getting damaged.
Back when I was on CH/HH-53’s, we had these 2x2 inch square pieces of leather. They were made so you could wrap them around a spot getting chaffed and the protected the lines. Those things worked great and lasted a long time… might need to find something like that for this application.

 

[87cr250r]

If there is a slight difference in tubing diameter do consider that 10mm and 3/8 are very close in size but not close enough to be compatible like 8mm and 5/16. If you had dimension related issues it was likely due to metric vs standard incompatibility.

For those trusting their these lines are as old as the truck experience, diesel fuel has changed recently. The GTL fuel in my linked article is synthetic diesel and the article was claiming that despite being the same fuel the source has significant impact on longevity of nylon lines.

I work in the California marine industry. We were forced to switch from Diesel #2 to R99. The engine manufacturers said no problem but we're running into issues everywhere else mostly related to the specific gravity of the fuel.

 

[Floridianson]

Maybe I should have mentioned you need to buy the dot Synflex fittings to fit the dot Synflex line. And you make it longer than the original loop it down more. Daydreaming one day and I thought if I use the push lock fittings and if I carried an extra 6 ft piece of Synflex line I could always drain some fuel into a Jerry can using the intake pump.

 

[HDN]

If there is a slight difference in tubing diameter do consider that 10mm and 3/8 are very close in size but not close enough to be compatible like 8mm and 5/16. If you had dimension related issues it was likely due to metric vs standard incompatibility.

For those trusting their these lines are as old as the truck experience, diesel fuel has changed recently. The GTL fuel in my linked article is synthetic diesel and the article was claiming that despite being the same fuel the source has significant impact on longevity of nylon lines.

I work in the California marine industry. We were forced to switch from Diesel #2 to R99. The engine manufacturers said no problem but we're running into issues everywhere else mostly related to the specific gravity of the fuel.

So the diesel #2 at the pump isn't just the low-sulfur stuff I thought it was?

 

[87cr250r]

If you're in California you get CARB diesel fuel. Everywhere else has EPA diesel fuel.

The exact formula of fuel you get will vary station to station. There should be a sticker on the pump that says what type of diesel you're getting.

 

[jeffhuey1n]

Thank you for all the information. There’s a lot to think about as applied to plastic fuel lines. All my repairs and reinstallation is complete and the truck started and ran without leaking.
I found the mysterious bolt while searching for a bolt that dropped into the frame. It’s a very small thing with a dab of yellow paint and holes for safety wire. I’ll dig into that problem at some other time.
Pics of the reinstalled line with the repair coupling in place.

 

[Jbulach]

I bought a length of nylon type hose from NAPA. It had similar dimensions as the original. I also bought new compression doohickeys (not sure what they’re called) and inserts to prevent the line from being crushed. None of that worked. There is a slight difference between the original and civilian versions. I dug through my immense stash of parts and came up with a compression splice. It’s a multi piece brass fitting. I cut out the bad piece, about an inch, and installed it. After test fitting, I loosened up one side of the splice so I could get the line aligned with the fitting on each end. Installed everything including the clamp and then turned on the master power. No leaks. By then the sun was going down and it was getting really cold. I’ll need some abrasion pads to protect the line from getting damaged.
Back when I was on CH/HH-53’s, we had these 2x2 inch square pieces of leather. They were made so you could wrap them around a spot getting chaffed and the protected the lines. Those things worked great and lasted a long time… might need to find something like that for this application.

Assuming your working with 3/8od tubing?

https://www.eaton.com/content/dam/e...c699-diesel-fuel-tubing-brochure-pll_1173.pdf

Synflex 3/8 diesel fuel tubing has an ever-so slight smaller ID and a little bigger OD (thicker wall) than Synflex 3/8 DOT air brake tubing.

https://www.eaton.com/content/dam/eaton/products/fc/hose-and-tubing/resources/Eaton-synflex-eclipse-air-brake-tubing-product-details-en-us.pdf

IIRC the fuel tube calls for special fittings. It’s very tight but I have forced fuel tubbing into dot push connect fittings with careful deburring/beveling of ID and OD as well as proper lube. Not sure if you can get the ferrule of a conventional DOT compression fitting over fuel tube or not though? You would want to put the insert in after the nut and ferrule is on if possible… and of course use at your own risk!

 

[Jbulach]

Also, I have heard of plenty of people using DOT air brake tube for fuel….

 

[jeffhuey1n]

Also, I have heard of plenty of people using DOT air brake tube for fuel….

Yes, that is what I bought at NAPA. The tubing, inner and outer two pieces were all purchased. The only original parts were the fittings(?). When I tried to put them all together, they just wouldn’t fit together.