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1998 K3500 rear brake line leaking.

9K views 57 replies 11 participants last post by  70monte 
#1 ·
Line that goes from the fitting right behind the gas tank to the block mounted on the rear axle sprung a leak today. Does anyone know what size line this is? I'm thinking it's 3/16th but want to make sure.

Does the gas tank have to come down to unscrew the line from the fitting behind it? Has anyone been able to remove the line without taking the tank down?

Tank is about 3/4th full and I don't want to take it down if I don't have to as I really have no real good way to do this.

I'm sure this is going to turn into a mess because I'm sure the fittings will not come loose. I've sprayed some penetrating oil on the fittings as well as a mixture of auto tranny fluid and acetone.

Thanks for any ideas on fixing this problem.

Wayne
 
#5 ·
No, it's the hard line that comes from the front of the truck and goes into the union that the rubber flex hose is attached to. There is a coupler that separates the part that I need to repair to the front run of line. This coupler is behind the gas tank so there is not easy access. You can see it if you look up from under the truck because it is between the gas tank and the frame. The rest of the line is attached to the inside of the frame.

I will check out the company SS tube. Thanks.

Wayne
 
#6 ·
That rear coupling is part of the rear flex hose. Cut the steel line off at the line nut. Remove the nut with a six point socket. Follow the line forward of the fuel tank. See if there is a union there somewhere. Or if the line is not rusted cut the steel line with a tubing cutter. Run anew line up behind the fuel tank to the rear connection. It really is not to hard to do. Do you no how to do a double flare? Do you have 4 wheel ABS? If you do and the anti lock unit gets air in it you will need a scanner that has brake bleed capabilities to do the job correctly.
 
#7 ·
Replace the WHOLE line from the front to the back. Either the s.s. option or they make an anti rust type line.
 
#9 ·
Thanks for the replies. I do know how to do double flares and have the equipment to do so. I will try and take some pictures of what I'm talking about. The rear flex hose is a separate piece on this truck and is not part of the hard line that I need to replace.

The piece that I need to replace is attached to the union that is between the fuel tank and the frame and screws into the block that the rear flex line screws in to.

The lines toward the front of the truck still look good as they have undercoating sprayed on them. Even the line coming out of the union behind the fuel tank going toward the front that have no undercoating on them have no rust on them.

This truck appears to only have front ABS.

I'm going to try to take apart the lines today after work and see what happens. I may have to unscrew the line further up toward the front. Thanks again.

Wayne
 
#10 ·
Just cut the line in a spot that's easy to get at and is not rusty, install a union coupler and snake the new line back.
 
#11 ·
Check with your local napa store. I heard that they are now offering SS lines for popular makes and models pre-bent.
 
#12 ·
I did find some pre-bent kits on ebay in regular steel line and in SS for this truck. One kit is $190 for the SS and the other is $290 for the SS. I also may end up having to replace all of the lines mounted to the rear axle and going to the wheel cylinders because they look pretty rusted and I don't know if I can get the bleeders open on the cylinders which may cause me to have to put new wheel cylinders in it.

I have been spraying all of the connections and bleeders the past few days with penetration oil to see if maybe I can get them open. I may just end up replacing everything depending on what happens but given my luck, things will go bad. Thanks again for the info.

Wayne
 
#13 ·
190.00 for prebent line for a 98....wanna buy a bridge to? I got one real cheap.
 
#14 ·
#15 ·
dieselss;2020566 said:
190.00 for prebent line for a 98....wanna buy a bridge to? I got one real cheap.
That is the cheaper of the two stainless steel kits. These both supposedly have all of the brake lines for the truck but they still are very expensive.

Most of the lines on the truck look okay, it's just every thing in the back that looks back, including the rubber flex line. I'm just trying to fix what is messed up right now.

Thanks to the link.

Wayne
 
#16 ·
U have disc or drum in rear? I have a 98 c-2500 its still has drums in rear. Just run a new line all the way back, just feed it up in the frame by the fuel tank to the new flex hose. Then run new lines to whatever you have at wheel ends. The brake lines from auto parts store are gonna cost maybe 35 bucks.
 
#17 ·
Buy a roll and replace all the lines now if you know how to double flare. Once one goes they all go shortly so why wait it's not that expensive $30-35 for a roll and $10 on fluid and usually you can reuse the fittings just spray penetrating fluid on them first. Literally the most time consuming part is bleeding the lines.
 
#18 ·
My truck has drums in the back. I may try replacing all of the lines but I believe I have two different line sizes on different parts of the brake system so I would have to buy two rolls. I'm just hoping to get this repaired without draining the master cylinder. I'm going to tackle this on Friday on my day off and see what happens.

The last truck I had to build brake lines for was a 1996 Ford F150 and the lines ended up snapping off at the wheel cylinders on both sides so it turned into a big mess because I almost could not get the wheel cylinders off.

This chevy has more rust in the rear than that truck did so I'm sure something is going to go wrong. I've not had much good luck working on vehicles lately.

Wayne
 
#21 ·
I'm sure that is what I'm going to do. I still have not fixed the truck due to me getting sick at the end of last week and the beginning of this week. I'm still not feeling great plus it's been in the late 80's and early 90's here with high humidity so I have not felt like doing anything. I will see how I feel tomorrow on my day off.

Wayne
 
#23 ·
Well, I finally got the old line out and a new one in. I guess soaking the connections down with different kinds of penetrant worked because all of the connections came loose with no problems as well as the bleeder valves.

My Eastwood 180 degree tubing bender did not work worth a darn so the new lines are not bent like the old ones were plus I was about 4" too short on the line so I had to take some of the bends out. My other cheap tube bender did not work very well either. I may have to get a pair of tubing bending pliers and see if they work better.

I still need to bleed the brakes as it got dark by the time I got the line back in. Hopefully that will go ok because there is no room at the back bleeders for a wrench to open and close them. I had to use a socket and small rachet to even open them but you can't have a hose hooked up to the bleeders with the socket on.

I didn't get any fluid out of the passenger side rear bleeder when I opened it so I hope it's not plugged. It still had the rubber cap on it.

Wayne
 
#25 ·
Well, no success on getting the brakes to work. I did have one leak where the hard line screws in to the rubber line at the rear but I got it tightened up. I bled both rear wheels and still no brakes. Brake pedal goes all the way to the floor and brake light is on in the instrument cluster.

I decided to try and bleed the front wheels but I could not get the bleeder screws unscrewed so I soaked them down with penetrant and will let them sit.

The master cylinder never went dry and the fluid lever never really got very low because I didn't drive it very far after the line blew so I can't imagine that air got up into the master cylinder but I guess it's possible.

I bled the front brakes back in 2009 when I put all new calipers, brake pads, rubber brake lines, and hub/bearing assemblies on the truck.

This truck has the hydroboost system so I don't know if there is something special I need to do to bleed the rears. I had no problems back in 2009 bleeding the fronts.

Anyone have any ideas? I'm about fed up with messing with this thing.

Wayne
 
#26 ·
Did you get steady fluid outta both bleeders?
Did you try and bless the master?
Are the rear brakes adjusted properly
 
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