Brake line failure

Was driving on the highway last night when traffic stopped suddenly.  Hit the brakes and the pedal sank a lot.  Got the car stopped but it was scary.  Didn't feel any pop, just a sinking pedal.  Then the brake light came on with the constant dinging.  Haven't investigated yet because it was dark, but I am reasonably sure it is a metal line as the brake hose is intact.  There is fluid all over the right front undercarriage.  Pretty sure the leak is behind the plastic splash shield.  Going to use nickel copper brake line for the repair once I see where the leak is exactly.  My question is, what size are the brake lines, 3/16"?  What kind of flares?  I have a really good Mastercool hydraulic flaring tool that makes all kinds of flares, so that is no problem. Double flare or bubble flare?  How about the fittings, are they SAE or Metric?

LARRY70GS wrote:

Was driving on the highway last night when traffic stopped suddenly.  Hit the brakes and the pedal sank a lot.  Got the car stopped but it was scary.  Didn't feel any pop, just a sinking pedal.  Then the brake light came on with the constant dinging.  Haven't investigated yet because it was dark, but I am reasonably sure it is a metal line as the brake hose is intact.  There is fluid all over the right front undercarriage.  Pretty sure the leak is behind the plastic splash shield.  Going to use nickel copper brake line for the repair once I see where the leak is exactly.  My question is, what size are the brake lines, 3/16"?  What kind of flares?  I have a really good Mastercool hydraulic flaring tool that makes all kinds of flares, so that is no problem.  Double flare or bubble flare?  How about the fittings, are they SAE or Metric?

Bubble flares. Fittings are listed in the FSM, check yours, IIRC they are metric.

I replaced all my brake lines with that olive drab poly coated steel a few years (about a decade) ago, they have been fine since. I did not have the privilege of popping a line - the original lines had a lot of surface rust so I scheduled replacement for when I had $ and convenience. When I finally got around to it, one line had started weeping. Phew. Job's not bad with a handheld tubing bender and stock lengths HOWEVER there is one run that's too long for the lines CarQuest stocks, so I needed one union. The local mechanic I griped to about that told me STFU and just make sure the union is straight and tight. He was right of course.

One other thing - be CERTAIN to duplicate the stock routing in the fender wells (it makes this funny set of up and down turns) or else the tire will likely rub the brake line in turns. Also be sure to use the stone guard coils over the lines like they are from the factory. Not because they are "pretty" rather because no kidding they are needed although when you're under the car doing the job it does not look like it.

Thanks Albert.  Ordered everything from Amazon.  Stone guard, 25 ft. roll of line with bubble flare metric fittings.

Was looking in the FSM for fitting sizes, but coming up empty. Got a page number Albert?

I got some parts fiche info...


The flare nuts are mostly M10x1x17.3 Except, for some reason, a couple at the ABS servo are M12x1x17.6 and the bulk tube is GM 12547207, 25ft rolls. They don't show P/Ns for pre-bent tubing, just list the bulk tubing for all the hard lines including even the short ones. The stock tubing is bulk steel 3/16".

Thanks Albert. I ordered a roll of the new Nickel Copper brake line with an assortment of metric ISO fittings. I also ordered some ISO unions in case I need them. Never used this new line, but everything I read says it is good stuff. Much easier to bend. Just need to be careful flaring it as it is somewhat softer. I have a Mastercool hydraulic flaring tool that is worth it's weight in gold it works so well. Bubble flares are a one step process, basically the first step in a double flare. I'll practice making several flares before working on the car.

LARRY70GS wrote:

Thanks Albert.  I ordered a roll of the new Nickel Copper brake line with an assortment of metric ISO fittings.  I also ordered some ISO unions in case I need them.  Never used this new line, but everything I read says it is good stuff.  Much easier to bend.  Just need to be careful flaring it as it is somewhat softer.  I have a Mastercool hydraulic flaring tool that is worth it's weight in gold it works so well.  Bubble flares are a one step process, basically the first step in a double flare.  I'll practice making several flares before working on the car.

Been there, done that, you'll be 100% fine.

I just came across this thread, scary stuff. My car had an ugly bottom when I bought it which I subsequently had cleaned up, but I suspect the brake lines are probably really ugly. Is it worth spending extra money for stainless? I'm sure I'm not going to have this car another 20 years.
https://classictube.com/product/buick-riviera-brake-line-kit-199719981999-2/
https://www.inlinetube.com/products/bvb9605

Inspect all your brake lines, especially the rear. You can replace just the badly rusted portions using junctions and the copper/nickle line. That is what I did. You need a good flaring tool. My lines were only rusted in certain areas, the rest looked good. I recently had to replace a line in the front, from the ABS module to just in front of the R/S front wheel. I would look at the entire length of all the brake lines. Rusty lines are common, and they will fail at some point, pretty suddenly.

Awesome advice as usual Larry. I am about to bring my car in to finally have axles and the Gabriel struts installed so I will have my mechanic check all the lines. I would do it but I like living LOL.

Under the rad, across the rad lower support, the lines for the RF and both rear run across there, then down the RH frame rail. The AC lines condensation drips on them constantly across the front of the engine RH front . Stupid and thoughtless design. The nickel copper lines are a greatest choice. I never understood why GM and other manufacturers don't use stainless or nickel copper to begin with. Pennies more for a high end car . But I digress...
My OEM rotted/blew out while parked on a parking lot under the rad. I have the engine out for rebuild now so its the perfect time for this, if that's possible. So I ordered a set in Stainless Steel. I have done cutting flaring and bending allot on my cars in the past, but for this car I wanted to do it premium and easier ( premade). These lines are $250 USD which isn't as cheap as a roll of line and fittings, but what's my time worth? These InLine Tube lines are complete from the master cylinder to the wheels, all stainless . I also bought new proportion valves and all new hoses .

Stainless Steel Lines: inline Tube https://www.inlinetube.com/products/sbvb9605

The hoses and prop valves I got from Rock Auto.

Nice thing is Rock Auto stuff for these cars is very inexpensive and sometimes they are doing closeouts.

Classic Tube is literally 5 minutes from my house. They did the SS lines for my 95 over 10 years ago. They werent yet available so my dad had sent my original lines to them as a template. Never had an issue. I feel like $300 is a steal but if you are paying to have them installed as well obviously it goes up from there. I will vouch for the quality of the lines from Classic Tube though.

Thats all good to hear. They just shipped out 2 days ago. I will do them myself. I am going to take the ABS pump out and scrape/ wire wheel all the corrosion off the bottom cover plate and paint it with good rust paint to get some more life out of it.

Get rid of the steel brake and fuel lines replace with stainless steel I have 4 Rivs and 3 of them brakes failed while driving rusted from inside out. Have 5 Rivieras for sale know anyone.
https://i.servimg.com/u/f60/19/94/24/58/green_10.jpg

buck3647 wrote:

Get rid of the steel brake and fuel lines replace with stainless steel I have 4 Rivs and 3 of them brakes failed while driving rusted from inside out.  Have 5 Rivieras for sale know anyone.
https://i.servimg.com/u/f60/19/94/24/58/green_10.jpg

I'd appreciate you telling me where did you get the stainless fuel lines?

I see somebody already alerted you to Classic tubes bought from them also had my mechanic get material and make them at the shop. A must do !!!

buck3647 wrote:

I see somebody already alerted you to Classic tubes bought from them also had my mechanic get material and make them at the shop.  A must do !!!

They are not in the Classic tube catalog, although that may not matter much. I'll get around to contacting them.

For those who want a line set that bolts/splices in, see this: https://www.linestogo.com/buick-riviera-fuel-line-1998-3-8l-k-fl251-b2a-set/ or this: Part Number: 25704013, Supersession(s): 25649390, from a GM dealer or .GMPartsDirect.com - it's just the fuel feed pipe, $80 or more plus shipping.

The stainless lines I bought from inline tube are a a huge disappointment. To begin with the lines that go from the master cylinder to the ABS pump are wrong working from the ABS pump all of the terminations for the brake lines are in the wrong direction. On a 98 Riviera the terminations are on the right hand side or passenger side of the ABS block that sits on the driver side of the car. Well the lines that they give you are meant to terminate at the front of the block which is obviously not possible. Not only that they're all too long and they actually go right past the ABS pump. From the underside of the cars proportioning valves back the where the line stops and has a female fitting on it that's to connect to a male fitting to run to the left rear caliper, the male fitting and the female fitting are of a different size and thread and they don't mate together. So that's a problem. Being as it's Saturday I can't get ahold of anybody at in line to Ben I've had these for exactly 30 days so whether or not I'm going to get my money back I have no idea.... I am considering just cutting the lines replacing the fittings and just fabricating the lines to go from the ABS pump and join up for the rest of the lines as they run underneath the rad support use nickel copper alloy lines. ....big pain in the ass especially after paying $130 have them shipped here and $250 for lines. I do not recommend this product. After all this messing around I would have been better off just to fabricate my own lines with nickel copper.