Hummer H2 brake line size?

Anyone know what size the steel brake line is for a 2003 H2? The line runs from the front of the truck to the HCU under the drivers seat. The General seemed to use three different sizes of line on this truck and I don't want to spend all day getting the correct size line.

Thanks, Paul

I'm pretty sure it's just your average garden hose variety.

I have used one U.S gallon of brake fluid just gettin the blasted thing off the interstate.

All this just to be rid of this RUSTY roach and the sunroof leaks, ask me how I know

It will be 3/16, 1/4, or 6mm. On a beater just remove it and bring it to the parts store, match it up with one off the pre flared line rack and install it, if you have to get one that's too long just bend a loop or S in it. For limping it pinch off a solid section of the bad line with vise grips and zip tie the vise grips in place so the shaking doesn't break the line.

The line will be easy, but GM has a tendency to use odd sized threads on the fittings. It is possible you will have to buy the line, then use your old nuts and re flare one end.

I just replaced the lines in my wife's H2. First off I suggest removing the drivers seat and cutting an access hole through the floor under the BCM. Leave the mounting studs for the BCM in place.

Then go get a stainless steel brake line kit like I did. It includes all the hard lines for the whole vehicle. If you have had one line fail and have not replaced others you are going to find that virtually all will require replacement. If you want I can go look up the manufacturer of the lines I got they fit perfectly and all the fittings were correct. Cost was about $250 or so. Well worth it as it eliminated all the screwing around with making lines. Oh and the bends on the lines at the abs pump are very tight and on top of the pump that is mounted tight to the floor under the drivers seat. This is why I made the access panel in the floor. Also I ended up replacing one rear caliper due to a stuck blender.

Oh and yes this is a suck job. At least in my Denali I could lift the bed and the abs pump is mounted so the lines go in the side. Not in the H2. Lifting the body is not really an option and the pump is mounted in the worst possible way and place.

For the acces hole I cut it out with a wizzer. I the primed and painted the cut edges. I got a piece of stainless steel and cut to a half inch bigger on all sides. I set it in a bed of sonoborn np1 sealant and then screwed it in place with stainless steel sheet metal screws about two inches apart all the way around. I then dressed the sealant smooth let it dry and primed and painted it to match the interior floor. On the under side I dressed the sealant smooth and primed and painted it to match the bottom. It almost looks like a factory acces panel.

On my Suburban which is very similar, I lifted the body a few inches off of the frame, which was critical in replacing all of the brake lines, particularly where they go over the frame and for the rear line.

Because this is such a problem, GM sells complete pre bent brake line kits made from an improved material, for a very reasonable price, mine was under $100 shipped from Amazon for the OEM parts. It was a pain in the ass of a job, but much easier with the pre bent lines and body lifted a bit.

Thanks for the input, as for the rest of the system is has been hacked and slashed with other "repairs" by a number of people with varying degrees of skills Now it's my turn.

Paul B

Good luck. I did mine on my spare time and it took two weeks to complete.

Oh and another known failure is the wiring to a plug in the center console. It will cause the shifter to lock up as well as you will not be able to remove the key. I have a spare plug (I was sent two) if you need / want it.

Just finished up replacing the leaking line with a new green line section of 1/4 inch line, had to reuse the nut at the ABS/HCU.

Posting this in case anyone else is "lucky" enough to make this repair.

Paul B