Grinding noise and bad brake line

[Blackmar401]

Have had a grinding noise that was just when accelerating for a few seconds but now it's worse. I was thinking wheel bearings or the brake. To me it sounds like it's coming from the driverside back wheel. Truck was brought in for inspection today and somehow passed with that issue? Was counting on a fail and an anwser so I would know what to fix. Unfortunately my wide brought it and was told it's a bad front brake line, which doesn't make sense to me. The rear were done last year after the brakes gave out while driving. Now if there was a leak wouldn't that effect all the brakes or are there 4 separate lines that when failed can not drain the reservoir? Is it possible they were just trying to hustle my wife and sell her new brake lines, because the last set cost like $900 with some other small repair. We have 4 kids and only my income so money is tight and anything I can do myself needs to be done. I am a pipefitter so I'm sure I can get the lines replaced and bleed the brakes with the help of YouTube, I just don't want to go on long expensive fishing expeditions.


Edit. The back lines are bad, front were replaced last year so it makes more sense now. Would a leak cause the caliper to lock up

 

[Jimmyy]

It could be that rust locked up the caliper. Either from the line and/or water getting in from the bad lines. You should be able to make the repairs yourself. The lines would be the hardest part IMO.

 

[MassHoe04]

I have seen where the rubber brake lines on vehicles can collapse when the are old and shot.
When they collapse in on themselves, fluid can sometimes pass one way but not the other way.
I have heard complaints of brakes locking up because the fluid can't get past the restriction in the hose enough to all ow the caliper to release.
That hose collapse can make a caliper lock up.

Are the hoses old? Do they feel brittle? Cracks?

May not help, but something to check out. Won't cost anything to check hoses.

 

[rockola1971]

Which brake lines are "bad"? the rubber lines leading from around the frame to the calipers OR the steel lines lead from the frame to the ABS Valve Body? A collapsing rubber line will cause a caliper to hang up on the rotor. A steel line doesnt collapse, it blows out because it is so badly corroded which is very common on GM K chassis brake lines. You can buy the lines separately instead of a full kit since it sounds like you already replaced the front lines (steel)? The brakes are divided into two reservoir feeds in the reservoir. Take the cap off and you will see a plastic divider between the front and rear. If your rear springs a leak you wont empty the reservoir of all the fluid for the front brakes (although the reservoir will be quite low).
You likely have air in the ABS valvebody. Old school way of bleeding the brakes does not work on vehicles with ABS especially after replacing brake lines. You have to bleed the brakes with a bi directional scan tool. Its a one man job and no pumping of the brake pedal is needed. The scan tool uses the ABS to "pump up your brakes" for you. It is very fast and easy as can be. I recommend getting a clone Tech II scanner. The bleed function is in there among many many other diagnostics. If you feel adventurous you can even reset the 4 digit security code on you radio with the Tech II.

 

[Blackmar401]

Which brake lines are "bad"? the rubber lines leading from around the frame to the calipers OR the steel lines lead from the frame to the ABS Valve Body? A collapsing rubber line will cause a caliper to hang up on the rotor. A steel line doesnt collapse, it blows out because it is so badly corroded which is very common on GM K chassis brake lines. You can by the lines separately instead of a full kit since it sounds like you already replaced the front lines (steel)? The brakes are divide into to reservoir feeds in the reservoir. Take the cap off and you will see a plastic divider between the front and rear. If your rear springs a leak you wont empty the reservoir of all the fluid for the front brakes (although the reservoir will be quite low).
You likely have air in the ABS valvebody. Old school way of bleeding the brakes does not work on vehicles with ABS especially after replacing brake lines. You have to bleed the brakes with a bi directional scan tool. Its a one man job and no pumping of the brake pedal is needed. The scan tool uses the ABS to "pump up your brakes" for you. It is very fast and easy as can be. I recommend getting a clone Tech II scanner. The bleed function is in there among many many other diagnostics. If you feel adventurous you can even reset the 4 digit security code on you radio with the Tech II.

The steel lines are rotted and I couldn't really see the hoses in back as it was dark out last night and raining today and I don't want to go climb under the truck right now. I'm planning to replace steel and rubber, so I will need a roll of steel, a flare tool, the rubber hoses and ³/¹⁶ fittings, and this scanner which I will look into now. The grinding is miniscule today. Apparently the mechanic said it could be the 4wd selector possibly trying to engage the wheels or something. We have had a few instances of the switch acting up and things locking up and grinding. Never sending my wife to a mechanic again. It's taken me 3 days to slowly get the possibly correct details.

Unfortunately I don't have like $400 minimum for a scanner right now, they do have one that works through your phone for like $120 that says Its bidirectional. I also see that somepeople are able to still bleed it without one, am I missing something?

 

[rockola1971]

The Steel brake lines are double flares.
Tech II clone can be had on Aliexpress for around $300. But there is that ship time.