How to loosen a stuck flare nut on a fuel line

[timsch]

I've got a fuel line flare nut stuck where it threads into the fuel (gasoline) filter. I've been soaking it with Kroil for about 3 weeks now and can't get it to budge. I've banged on it as well. Hitting it with the torch is out of the question. I've put about as much force onto the flare nut wrench that the nut will take without rounding off.

Any recommendations? I've got a 250W Weller soldering gun that I thought about coming to post this. I'm willing to try anything as long as it's short of blowing myself up.

 

[kevin110]

Try to get a mini-hacksaw on the fuel filter fitting and try to cut carefully thru it to the male fitting at the end of fuel line.
It may take extra space. Perhaps the unit can be moved slightly out of position. Kevin110

 

[Steve in VA]

I've got a fuel line flare nut stuck where it threads into the fuel (gasoline) filter. I've been soaking it with Kroil for about 3 weeks now and can't get it to budge. I've banged on it as well. Hitting it with the torch is out of the question. I've put about as much force onto the flare nut wrench that the nut will take without rounding off.

Any recommendations? I've got a 250W Weller soldering gun that I thought about coming to post this. I'm willing to try anything as long as it's short of blowing myself up.

Perhaps a gentle attempt to tighten it might help. Couldn't hurt.

 

[Dusty MI]

There is a special wrench made to use on flare nuts. It is an extra heavy built hex end wrench with one hex side removed, that will slip over the copper tube.

 

[Hobo,NC]

I've got a fuel line flare nut stuck where it threads into the fuel (gasoline) filter. I've been soaking it with Kroil for about 3 weeks now and can't get it to budge. I've banged on it as well. Hitting it with the torch is out of the question. I've put about as much force onto the flare nut wrench that the nut will take without rounding off.

Any recommendations? I've got a 250W Weller soldering gun that I thought about coming to post this. I'm willing to try anything as long as it's short of blowing myself up.

My #1 go to is a flair nut crow foot socket (not any a good one) on a extension and rattle it with a impact it amaze's me what that combination can accomplish. All the other tools I have for this job are not ones a DIY guy would buy but if it was you day job you would not be without them.

 

[timsch]

I've tried repeatedly over this time to turn it in the opposite direction.

I do have a proper set of flare nut wrenches. I even went on ebay to buy a vintage Craftsman Professional set to use instead of my cheaper flare nut wrenches after seeing how much of a bugger this was being, and not wanting to round off the nut with bad tools.

Right now the machine is running fine, so I'm not taking a hacksaw to anything just yet and wind up immobilizing anything. I'll keep that in mind if worse comes to worst.

 

[timsch]

I do have a set of crow foot wrenches, although I'm sure they're metric and are HF, so not good ones....

 

[Jim.ME]

I do have a set of crow foot wrenches, although I'm sure they're metric and are HF, so not good ones....

Hobo is talking about flarenut crowfoot wrenches, not regular (open end) crow foot wrenches. You want the six-point ones, like your wrenches. You can get individuals on eBay, McMaster Carr, or tool trucks are some sources. Your local parts store may be able to order the size you need.

 

[stevieb49829]

I've got a fuel line flare nut stuck where it threads into the fuel (gasoline) filter. I've been soaking it with Kroil for about 3 weeks now and can't get it to budge. I've banged on it as well. Hitting it with the torch is out of the question. I've put about as much force onto the flare nut wrench that the nut will take without rounding off.

Any recommendations? I've got a 250W Weller soldering gun that I thought about coming to post this. I'm willing to try anything as long as it's short of blowing myself up.

Is it leaking? Is this a segment of fuel line you can reconstruct once its off? Can it be replaced with barb connectors and rubber fuel line? If that was all "yes" answers I'd saw it off near the flare nut, slip a 6 point end wrench over it and break it loose. Then either build a new steel line, or convert it to barb fittings and rubber fuel line.

 

[timsch]

Hobo is talking about flarenut crowfoot wrenches, not regular (open end) crow foot wrenches. You want the six-point ones, like your wrenches. You can get individuals on eBay, McMaster Carr, or tool trucks are some sources. Your local parts store may be able to order the size you need.

You're right. Lazy reading on my part....

 

[rustred]

I've got a fuel line flare nut stuck where it threads into the fuel (gasoline) filter. I've been soaking it with Kroil for about 3 weeks now and can't get it to budge. I've banged on it as well. Hitting it with the torch is out of the question. I've put about as much force onto the flare nut wrench that the nut will take without rounding off.

Any recommendations? I've got a 250W Weller soldering gun that I thought about coming to post this. I'm willing to try anything as long as it's short of blowing myself up.

be interested to know what this is one so a person can decide on a decent answer. you might have to just cut it out and replace the line with a union in the splice. ??? dont know what your working on.

 

[timsch]

Is it leaking? Is this a segment of fuel line you can reconstruct once its off? Can it be replaced with barb connectors and rubber fuel line? If that was all "yes" answers I'd saw it off near the flare nut, slip a 6 point end wrench over it and break it loose. Then either build a new steel line, or convert it to barb fittings and rubber fuel line.

No, it's not leaking. The filter has just been on too long.

It's my truck, so rubber line with barbs isn't an option for me.

I don't know if there's enough play in the line to cut it off and reconstruct it, although if nothing else works, I may consider doing that after checking for freeplay. That'll be after I try something like Kevin's recommendation in #2

 

[timsch]

be interested to know what this is one so a person can decide on a decent answer. you might have to just cut it out and replace the line with a union in the splice. ??? dont know what your working on.

Sorry to be unclear. It's my '98 T100 truck with steel lines going into my fuel filter.

 

[rustred]

Sorry to be unclear. It's my '98 T100 truck with steel lines going into my fuel filter.

then if u tryed with no success , cut the filter out and replace the line as required.

 

[used red MN]

Is it straight section away from the fitting 3-4 inches? If so get a 6 sided deep socket and measure the depth, cut the line so the socket will go on it to remove the nut. Reconnect the line with a hose or if higher pressure fuel injection use a brass compression connector.

 

[Jim.ME]

Sorry to be unclear. It's my '98 T100 truck with steel lines going into my fuel filter.

If you can get at the sides of the fitting made on the filter, use a big hammer (other heavy steel block) on one side of the nut and tap on the side 180 degrees from the one the hammer is backing up. Work as many sides as you can, it might break up what is holding it. Of course if the problem is the line is rusted inside the nut, cutting the line may be the best answer.

 

[timsch]

Is it straight section away from the fitting 3-4 inches? If so get a 6 sided deep socket and measure the depth, cut the line so the socket will go on it to remove the nut. Reconnect the line with a hose or if higher pressure fuel injection use a brass compression connector.

Yes, I've got plenty of straight fuel line length. I'll keep that on the list. Thanks.

 

[rustred]

Is it straight section away from the fitting 3-4 inches? If so get a 6 sided deep socket and measure the depth, cut the line so the socket will go on it to remove the nut. Reconnect the line with a hose or if higher pressure fuel injection use a brass compression connector.

u razzed me, now i am wondering why u want to keep the nut on the old filter? just need a chunk of steel line and flare one end then connect it to the cut line with a union.

 

[timsch]

If you can get at the sides of the fitting made on the filter, use a big hammer (other heavy steel block) on one side of the nut and tap on the side 180 degrees from the one the hammer is backing up. Work as many sides as you can, it might break up what is holding it. Of course if the problem is the line is rusted inside the nut, cutting the line may be the best answer.

I should have access to try that on at least a couple of faces. I can't tell if the line is rusted, but I did get the nut with the same line material to finally spin a couple of weeks ago, so I'm hopeful it's not the line itself.

 

[timsch]

u razzed me, now i am wondering why u want to keep the nut on the old filter? just need a chunk of steel line and flare one end then connect it to the cut line with a union.

I just meant I liked the idea used red MN said about cutting the line and slipping a deep socket over it to break the nut. I'm making a list of things to try and in what order, at least in my head.