Stuck Brake Line Flare Nut - PeachParts Mercedes-Benz Forum

Diesel911 · #1 03-25-2020, 09:42 PM

This is not on a Mercedes but a stuck Brake Line Flare Nut is a generic issue on a lot of vehicles. (Also I am promoting the use of the Crowfoot Flare Nut Wrenches.)

I sprayed the Flare Nut down with PB Blaster and let that soak in for 1 hour. But, even with a Crowfoot Flare Nut Wrench It did not want to budge with the force I was willing to exert on it.

Since I was removing the Flare Nut to change the Brake Hose damaging the Hose was not an issue. I used a propane Torch and heated the steel hose end and the heat worked like magic and the Flare Nut turned easily.

Note that there would have been no room for that special Vice Grips that is made for stripped Nuts and Bolt heads and there was actually little room for a regular Flare Nut Wrench and I did not have a regular 12mm Flare Nut Wrench. Hence the use of the Crowfoot Flare Nut wrench.

In the picture I have an larger metric set that I got on eBay from eBay which turns out to be more complete I don’t recall the cost on that.

The other 2 sets are from Harbor Freight and without the 20% off coupon are $12-$13 dollars. Unfortunately the Harbor Freight Metric Set dose not have 11mm nor a 16mm.

With care you can use the 17mm Crowfoot Flare Nut on your Fuel Injection Hard Line Nuts.

The reason for the 2 sets of metric Crowfoot Flare Nut Wrenches is that I could not find the 12mm I need from the ebay set when I changed the first Brake Hose last week and I bought another set from Harbor Freight just to get the job over with. Later I looked for and found the missing one and was able to use that today when I did the last hose.

In between that time I bought the Harbor Freight SAE Crow Foot Wenches as I had no set of them.

I too a Q-tip and dipped it in Never-seize type compound and coated the threads of the brake line flare nut with it. Next time it won't be stuck.

Junkman · #2 03-25-2020, 10:36 PM

Amazing all of the little tools you collect that would have been expensive &/or hard to get when we started wrenching. I remember when a corded drill was $40 but I was only making $3.50/hr. (that was after a couple of raises.

Zulfiqar · #3 03-26-2020, 12:02 AM

If you encounter a rounded nut - buy yourself a knipex cobra head pliers - I have not met a single nut that won against it.

It grips harder than a pipe wrench but has a thinner profile.

dieselbenz1 · #4 03-26-2020, 03:08 AM

Did you get it cherry red with your torch? I do that 2 or three times reach time hitting it with some cheap penetrating oil as it cools. Never an issue.

g300d · #5 03-26-2020, 05:01 AM

Very timely, I was wanting to do the rubber brake lines on the 300D as the rubber is starting to show fine cracks all over. I tried and the flare nuts are on tight.

Will be trying heat and penetrating oil.

barry12345 · #6 03-26-2020, 09:52 AM

The inner part of the fitting also gets rusted to it. Twisting the steel line sometimes. Things get pretty rusty where I live so I always heat things up to avoid that as well. What is required varies by area. The heat and cool three times rule is used in many places. Especially on bleeder screws.

Diesel911 · #7 03-26-2020, 10:02 AM

Quote:

Originally Posted by Zulfiqar

If you encounter a rounded nut - buy yourself a knipex cobra head pliers - I have not met a single nut that won against it.

It grips harder than a pipe wrench but has a thinner profile.

Looks like Homedepot sells them. I noticed when I looked in image.google that there is versions with different jaws.

I did not want to round off the head of the Flare Nut.
With what I was doing the issue was also room to use something else in. And I succeeded in not rounding the head off.

Diesel911 · #8 03-26-2020, 10:08 AM

Quote:

Originally Posted by barry12345

The inner part of the fitting also gets rusted to it. Twisting the steel line sometimes. Things get pretty rusty where I live so I always heat things up to avoid that as well. What is required varies by area. The heat and cool three times rule is used in many places. Especially on bleeder screws.

Ya, heat is very important to success a lot of the times. Even though heat often burns off the Oil when you re-spray the Oil the warm parts allow the Oil to get in better.

If you can get the line off with out damaging anything after you clean off the rust you can slide the nut back and coat the exterior of the line with a thick coating of Never-seize and then slide the Nut back on so that the inside of the nuts also gets coated and wipe off the excess. That usually keeps it from rusting again.

Diesel911 · #9 03-26-2020, 10:12 AM

Quote:

Originally Posted by g300d

Very timely, I was wanting to do the rubber brake lines on the 300D as the rubber is starting to show fine cracks all over. I tried and the flare nuts are on tight.

Will be trying heat and penetrating oil.

If you spray on PB Blaster (Homedepot sells it but it comes with out the little tube) or forum members claim Kroil is even better and can do that multiple times over the course of a week or two you may not need any heat. But, even if you are using a flare nut wrench you need to decide if you think you are getting close using too much force on it.

Diesel911 · #10 03-26-2020, 10:16 AM

Quote:

Originally Posted by dieselbenz1

Did you get it cherry red with your torch? I do that 2 or three times reach time hitting it with some cheap penetrating oil as it cools. Never an issue.

I have never had to get something that hot to get it to loosen up especially not a Brake Line. In fact I only burned the brake line a bit where near the crimped area.
Unfortunately there is no way to describe to someone how much heat to use. I simply try to use the minimum I can.
If you heat it and it did not work you can always heat it more.

Diesel911 · #11 03-26-2020, 10:23 AM

Comment on heat. I never use an Acetylene Torch on this sort of thing. In fact if I had one working I could have used a small handheld butane torch on that area. The Propane Torch I used was a large for the job and in this case I was lucky that the tank is nearly empty because I was able to get a small sable flame with not a lot of pressure behind it.

I have 2 electric heat guns I used for stripping paint and they get hot enough to help but spread the heat over too large of an area.

I have an Acetylene Torch Set That I bought back in the 1970's and used it only once or twice after I cut up a car with it. Since that time I am not sure where my Gauges are for it and even if I could find all of the set I am sure my hoses likely have rotted out. Since that time I have not ever needed that much heat.

barry12345 · #12 03-26-2020, 03:08 PM

Where you reside fortunately for you makes ox/acy not often required. Here without it forget doing many jobs on cars.

I have seen cars in better overall condition in junkyards in the south than those on the roads here.

Zulfiqar · #13 03-26-2020, 03:23 PM

Quote:

Originally Posted by Diesel911

Looks like Homedepot sells them. I noticed when I looked in image.google that there is versions with different jaws.

I did not want to round off the head of the Flare Nut.
With what I was doing the issue was also room to use something else in. And I succeeded in not rounding the head off.

I used a knipex cobra head pliers on a rusty brake flare nut on a ford, one shot of light heat and oil - and one heave with the pliers correctly installed and that nut broke loose with a bang.

If you correctly set the pliers you can grip a round pipe so hard that you can stand on the pliers handle.

Diesel911 · #14 03-26-2020, 04:21 PM

Quote:

Originally Posted by Zulfiqar

I used a knipex cobra head pliers on a rusty brake flare nut on a ford, one shot of light heat and oil - and one heave with the pliers correctly installed and that nut broke loose with a bang.

If you correctly set the pliers you can grip a round pipe so hard that you can stand on the pliers handle.

Thanks on that. I had a plumbing pipe one time and there was no room for a normal pipe wrench because it was next to a Wall nor was there room for a Chain type pipe wrench. So you never know what you might need.

I rooted around in my Tools desperately looking for some thing would work and I found a Wrench I bought for like $4 at a cheapie tool place. Like the one in the attaché picture made in Taiwan and had Automat Wrench cast into the handle.

If fit on but I was really skeptical if it was going to work or not since cheap tools often don't hold up on tough jobs. But, it worked!

I had that Wrench for like 5 years and never used it. Used it that one time and have not used it since. But, it was surly worth the $4 just for that one use.

It looks like a wrench that could also deal with a rounded Nut or bolt but the size would likely be too large for it to fit.

Diesel911 · #15 03-26-2020, 04:33 PM

Quote:

Originally Posted by barry12345

Where you reside fortunately for you makes ox/acy not often required. Here without it forget doing many jobs on cars.

I have seen cars in better overall condition in junkyards in the south than those on the roads here.

When I worked at the Naval Shipyard we encountered severely corroded stuff made of Steel but we did not work on vehicles so no issue with something as delicate as a Brake Line or Hose.

Because of the job description we could not use any welding stuff or torches normally so we were left with Chisels, grinders and saws or we had to file a work order and a few days later the guy would show up with a Torch.

When we had nuts that were badly rusted to studs we used a nut splitter or a sharp chisel to split the Nuts.