# 1998 K3500 rear brake line leaking.



## 70monte (Feb 5, 2008)

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


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## Randall Ave (Oct 29, 2014)

So your saying the rubber flex hose is leaking? Just get her up in the air as high as you can and have at it. Is it 4 wheel ABS? Better to change the rusted lines now than in a snow storm.


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## yukonslt3 (Mar 2, 2010)

it may be a 1/4'' if its not a 3/16th


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## rjigto4oje (Oct 27, 2010)

I just purchased a set of stainless steel lines from a company called ss tube, found them on eba. 220 dollars shipped to the door nice peoduct


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## 70monte (Feb 5, 2008)

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


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## Randall Ave (Oct 29, 2014)

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.


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## dieselss (Jan 3, 2008)

Replace the WHOLE line from the front to the back. Either the s.s. option or they make an anti rust type line.


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## Randall Ave (Oct 29, 2014)

I was kinda waiten for his reply if he nows how to do flares and such. I no he should probably change them all, better to do it now instead of during a storm. And does he have time to order parts and wait or need truck on road now like most of my customers.


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## 70monte (Feb 5, 2008)

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


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## dieselss (Jan 3, 2008)

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.


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## Plowtoy (Dec 15, 2001)

Check with your local napa store. I heard that they are now offering SS lines for popular makes and models pre-bent.


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## 70monte (Feb 5, 2008)

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


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## dieselss (Jan 3, 2008)

190.00 for prebent line for a 98....wanna buy a bridge to? I got one real cheap.


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## dieselss (Jan 3, 2008)

http://agscompany.com/product-categ...lines/poly-armour/domestic-lines-poly-armour/


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## 70monte (Feb 5, 2008)

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


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## Randall Ave (Oct 29, 2014)

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.


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## terrapro (Oct 21, 2006)

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.


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## 70monte (Feb 5, 2008)

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


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## averhoog (Aug 5, 2015)

The lines will be 1/4 inch from the master to the rear axle flex line all the rest of the lines are 3/16 inch just replace from the master to the flex line on the back real easy you should replace everything and get it done then you don't have to worry about it


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## averhoog (Aug 5, 2015)

The lines will be 1/4 inch from the master to the rear axle flex line all the rest of the lines are 3/16 inch just replace from the master to the flex line on the back real easy you should replace everything and get it done then you don't have to worry about it


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## 70monte (Feb 5, 2008)

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


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## leolkfrm (Mar 11, 2010)

for $60 you can buy 25 ft hi-ni line, stainless preformed are nice but hard to feed thru, been there done that....if it was a restoration project ss all the way


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## 70monte (Feb 5, 2008)

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


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## Randall Ave (Oct 29, 2014)

Chevy didn't give much room in there. Just get someone in the seat and bleed them. I'v done it with a 1/4 ratchet and socket. Did the master go dry? You may have to run a scanner and do a brake bleed procedure. Always remember, if it was easy the women would be doing it.


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## 70monte (Feb 5, 2008)

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


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## dieselss (Jan 3, 2008)

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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## averhoog (Aug 5, 2015)

Leave truck running while doing it try driving withitnow if you got some braking and get the abs to kick on by locking up the brakes a few times then bleed again definitely want to bleed out the front aswell good luck


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## 70monte (Feb 5, 2008)

I did get steady fluid out of both rear bleeders. I have not tried bleeding the master cylinder yet. I was hoping I would not have to do that since the master cylinder never went empty. I'm not sure if the rears are adjusted properly but the brakes worked fine before the line blew. I bought this truck used in 2007 and have not touched the rear brakes. I do back up hard periodically so the rears can self adjust but who knows if that is actually working.

I'm going to have to get the front bleeders to open before I can continue. I'm hoping that the penetrant I used will break them free after sitting for a few days. This truck is not a daily driver so there is no hurry.

I may end up having to take it somewhere since I don't have a scanner to activate the ABS system if it ends up that air got up that far. I guess it is possible that when I was driving the truck back from the doctor's office after the line blew that trying to activate the brakes drew air up into the ABS unit and master cylinder.

Wayne


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## dieselss (Jan 3, 2008)

I do back up hard periodically so the rears can self adjust but who knows if that is actually working.

Almost never works, don't rely on that alone


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## Randall Ave (Oct 29, 2014)

I am not sure of the system you have. On the ABS unit there is a one wire plug on a small switch. Remove the wire, remove the switch, I think its a 5/8 plastic hex. This works the red dash lamp. Now start the engine and pump the brake pedal, then push hard, it may reset the valve. Now bleed the brakes again. Your gonna have to bleed a lot of fluid thru it. Then you need a good scanner to run a brake bleed procedure, then bleed system again. Are you getting good flow from bleeders?


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## 70monte (Feb 5, 2008)

Randall Ave;2026083 said:


> I am not sure of the system you have. On the ABS unit there is a one wire plug on a small switch. Remove the wire, remove the switch, I think its a 5/8 plastic hex. This works the red dash lamp. Now start the engine and pump the brake pedal, then push hard, it may reset the valve. Now bleed the brakes again. Your gonna have to bleed a lot of fluid thru it. Then you need a good scanner to run a brake bleed procedure, then bleed system again. Are you getting good flow from bleeders?


Until I can get the front bleeders open, I'm kind of stuck on getting all four wheels bled. I did get good flow at the back bleeders.

I don't have a scanner that can operate the ABS system so I'm going to have to take it somewhere for that and because I don't have any brakes, I'm going to have to trailer it.

The brakes worked fine before the line broke so I don't think anything is out of adjustment. I'm sure it's got air in the lines somewhere. I bled the back wheels twice and that didn't work. I'm having doubts if doing the fronts will do any good. I'm not familiar with the hydroboost system so I will have to do some more research. Thanks again for all of the replies and ideas.

Wayne


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## Randall Ave (Oct 29, 2014)

Remove that switch and try to bleed it like I said. U got nothing to loose, but some brake fluid.


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## dieselss (Jan 3, 2008)

Hydroboost is not your issue you still have air. 
You said you only blead the rears twice? As in pump.....hold......crank bleeder. That procedure only 2 times a side?


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## 70monte (Feb 5, 2008)

Randall, I will check out the ABS switch and see what happens.

dieselss, What I meant is that I bled the rears two separate times using a Mityvak vacuum bleeder. I did each side multiple times both times I did it. I guess I can try bleeding the rears some more but I got plenty of fluid through each time I have bled them with no apparent air in the tube.

I'm not new to bleeding brakes and have done many vehicles over the years without problems. This is the first time I have had an issue

Wayne


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## dieselss (Jan 3, 2008)

Ditch the mity vac and use the old fashioned way, a foot and a wrench.


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## Randall Ave (Oct 29, 2014)

Gotta agree with Dieselss, you have to foot bleed it. If the safety valve is tripped your not getten all the air out.


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## 70monte (Feb 5, 2008)

I guess I'm going to have to find someone to help if I'm going to do it the old way.


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## Randall Ave (Oct 29, 2014)

Wife, girl friend, neighbor. Beer helps.


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## Rick547 (Oct 9, 2009)

Randall Ave;2026083 said:


> I am not sure of the system you have. On the ABS unit there is a one wire plug on a small switch. Remove the wire, remove the switch, I think its a 5/8 plastic hex. This works the red dash lamp. Now start the engine and pump the brake pedal, then push hard, it may reset the valve. Now bleed the brakes again. Your gonna have to bleed a lot of fluid thru it. Then you need a good scanner to run a brake bleed procedure, then bleed system again. Are you getting good flow from bleeders?


I've read that if you push the brake pedal to hard. You can break the cups in the master cylinder.


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## dieselss (Jan 3, 2008)

Rick547;2026538 said:


> I've read that if you push the brake pedal to hard. You can break the cups in the master cylinder.


Can you post that info, where you read that? Or what publication?


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## Rick547 (Oct 9, 2009)

dieselss;2026539 said:


> Can you post that info, where you read that? Or what publication?


Let me see if I can find it again.


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## Rick547 (Oct 9, 2009)

dieselss;2026539 said:


> Can you post that info, where you read that? Or what publication?


Here is one site. http://www.linnbenton.edu/auto/brake/bleed.html


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## dieselss (Jan 3, 2008)

Rick547;2026538 said:


> I've read that if you push the brake pedal to hard. You can break the cups in the master cylinder.


So in what you posted, the link, says nothing about breaking cups in the master. Just that if you press "to the floor with an empty master, you COULD damage seals" 
Also stated that after such bleeding master cylinder replacement is common......sorry but I'd love to see the facts on that statement.


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## averhoog (Aug 5, 2015)

I'm a mechanic for 15 years never had to replace thr master because of bleeding it pump a few times then hild while someone is opening bleeder screw do all the wheels until air is out if still soft then drive on gravel and lock up brake so that the abs pump kicks in and then re bleed everything and should be good


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## kimber750 (Sep 19, 2011)

70monte;2026079 said:


> I did get steady fluid out of both rear bleeders. I have not tried bleeding the master cylinder yet. I was hoping I would not have to do that since the master cylinder never went empty. I'm not sure if the rears are adjusted properly but the brakes worked fine before the line blew. I bought this truck used in 2007 and have not touched the rear brakes. I do back up hard periodically so the rears can self adjust but who knows if that is actually working.
> 
> I'm going to have to get the front bleeders to open before I can continue. I'm hoping that the penetrant I used will break them free after sitting for a few days. This truck is not a daily driver so there is no hurry.
> 
> ...


I have had issues with portioning valve sticking after blowing break line. Until you can get front lines bleed valve will not trip back. You can crack the hoses at the calipers if you can't get bleeders open since there should be no air in the calipers.


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## Rick547 (Oct 9, 2009)

dieselss;2026546 said:


> So in what you posted, the link, says nothing about breaking cups in the master. Just that if you press "to the floor with an empty master, you COULD damage seals"
> Also stated that after such bleeding master cylinder replacement is common......sorry but I'd love to see the facts on that statement.


When I get time I look a litter further. I wish I could remember exactly where I read it.


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## Randall Ave (Oct 29, 2014)

What I think that was in relation to is under normal braking the master cylinder only travels so far. Brake fluid will build up a slime coating per say. Then when the pedal goes to the floor it is possible to make the master cylinder bypass. But this is not very probable. I've only ever had this happen once. You will not brake the internal components by pushing the pedal to the floor.


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## 70monte (Feb 5, 2008)

My fiancee said she would help me bleed the brakes this Saturday so maybe I will find out something this weekend.

Wayne


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## Randall Ave (Oct 29, 2014)

Hope it works, can only cost you a nice dinner, possible jewelry store trip.


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## 70monte (Feb 5, 2008)

I'm hoping to work on it today after she goes grocery shopping. I'm thinking of getting a new Master cylinder just to eliminate that from the equation.

Wayne


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## Randall Ave (Oct 29, 2014)

I think your wasting your money on the master, but its your call. If you replace that you no how to bleed it?


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## 70monte (Feb 5, 2008)

Well everything is on hold again as I still can't get the front bleeders open. I sprayed them down again and will do it everyday this week and will try again later. I did get a bleeder valve wrench so that I can do the rears easily.

I've decided not to get a new Master cylinder unless I end up needing one. I've bench bled master cylinders in the past but like I said before, I have not messed with the hydroboost system so I don't know if that comes into play as the master cylinder is bolted to the hydroboost unit.

Wayne


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## dieselss (Jan 3, 2008)

Again the hydro boost doesn't matter to bleed your brakes. 
If soaking the calipers don't work, may need heat. Actually I'd try that now instead of waiting.


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## Randall Ave (Oct 29, 2014)

Did the master ever go dry? The line that failed was in the rear correct. It's a split system, I don't see how you have air in the fronts. Just give the rears a good foot bleed.


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## 70monte (Feb 5, 2008)

I finally got the brakes working. I did the old fashioned foot bleed like you guys suggested. The brakes work better than they have since I bought the truck almost eight years ago. The brakes start engaging as soon as you press the pedal.

I just bled the rears and didn't even try opening the fronts again.

I ended up fixing two other problems that cropped up after I got the brakes to work. I had no tail lights and my blinkers were blinking very fast with hardly any light output at the tail lights. All fuses and bulbs were good. I tested the battery and it tested bad. The battery was only a year old and I have had the truck on a battery tender when it's not being used which obviously did not work. I got a new battery under warranty and still had the light problems.

I finally discovered a ground wire that had come out of it's connector at the rear of the truck and fixed the light issues.

I want to thank all of you who gave your input and ideas and convincing me to foot bleed the system instead of giving up and taking it to a shop. I also owe my fiancee who helped me out on the foot bleeding procedure. Take care and thanks again.

Wayne


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## Randall Ave (Oct 29, 2014)

Glad its working. Now go get her a diamond necklace to go with that ring. Remember, its only money


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## 70monte (Feb 5, 2008)

She isn't really in to necklaces. Taking her out to eat will probably be enough payment for her.

Wayne


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## 70monte (Feb 5, 2008)

I did forget to mention that when I bled the brakes, I first did each side with the truck off and then did it with it running.


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