i suffered the famous corroded brake line issue for GM vehicles... have a 2003 H2 with only 52000 miles on it and when i took it out for a warm up round in my estate... about 1 mile round .. the brake pedal depressed fully when i slowed down...drove it back and pulled up to the driveway.. and true enough brake fluid dripping..just beneath the driver side...

placed a drip pan underneath and started checking the lines from the Brake Master Cylinder reservoir(1)


to the BRAKE CONTROL MODULE


the 2 pipes from the from the reservoir (where we top up brake fluid) to the BCM was badly corroded(looks something like this ) and this was the part which leaked... darn GM... that location where the brakelines are placed/run along is a magnet for dirt / salt.

Tracing further from the BCM to the front left brake line , it was also corroded and just started leaking...

i know these brakelines from the reservoir and BCM would have to be hand fabricated.. and i am wanting to do it and also fixed the front brake lines ...

intending to use stainless steel tubes .. but i would need some help in determining the tube dimensions as i read that the connectors from the reservoir and BCM are specified sizes (also dun have that info on dimensions)...

the brake line part number from GM is GM 12548430 TUBE. LINE

i read on some forums on GM vehicles.. that the tube is 3/16" tubing...

question i have is
1) should i lift the body slightly off the main frame.. which i wouldneed to loosen all 12 isolator bolts.. the space is tight.. but looking at it.. it looks doable without lifting the body off...i will have sore fingers later on..
2)do i need to flare the tubes before connection to the reservoir or BCM?
3) dimension of brake line tube.. i intend to get stainless steel tubing and self fabricate them not sure if this is the right size.. but something like this

had a simple diagram done.. redone the diagram.. this is right now i had it traced...

 

found this full complete part list for the 2003 H2... with exact GM part number....

http://www.autoricambi-euroamerica.c...ofessional.pdf

 

darn... look at the corrosion from the BCM...

the front is the far end of this pic. Pic was taken from the rear of the BCM , camera facing front



am trying to remove these as these are the main line from the brake reservoir ... and looks like i am going to try the PSF/acetone mixture.. and see what it does to it


the other 2 lines on the side of the BCM facing the rear

 

really weird .. GM part 15724652 for these fittings are supposing "NUT,RR BRK FRT PIPE(7/16-24X0.36)(0.30 THD, .056 LENGTH, 1/4 TUBE, STL, GM7113M)(8.963)" which is item 3 and 9 in the first pic

 

any help would be appreciated... if someone can help me identify the part number for these fittings

 

I just went through this . I bought preformed stainless lines from Classictube.com. $329. They fit perfect. I also got stainless flexible hoses. good luck.

for what its worth. I've never had this happen on other vechiles. Is this problem just a sign of cheap chineese steel?

 

how did you get the fittings loose from the BCM?

i am going with nickel copper steel lines

 

I used VISA.


I had the local shop do the work.

 

VISA is heavy.... i use elbow grease so far...

still have not managed to free the nut... will coat in the PSF / Acetone mix tonight and try again.. with a VISE GRIP.. the nut will be replaced anyway..

 

AC Delco got back to me on the fittings size..

seems this is a new listing of part numbers but it states the brakefittings size clearly..