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Discussion Starter · #1 ·
Hey everyone! Need some insight on a brake issue.

Did the front brake blazer upgrade on my 2000 S10 pickup and added an LSMFG disk brakes kit on my 8.8 in the rear. Been trying to get my brakes bled for the past few weeks and have not been successful. We tried the following:

1. Conventional bleeding and gravity bleeding procedures countless times
2. Replacing the brake booster and master cylinder (stock s10) and bench bleeding the master cylinder
3. Teflon taped the bleeders for possible fitment issues
4. Vacuum bled with a bleeder pump
5. Cycled the abs module multiple times with a scanner
6. Replaced all the break lines on the rear end and checked every point for leaks with soapy water.

Pedal is still spongy. It gets hardish after a few pumps but goes softer when it sits. All data suggests a leak or air in the system somewhere but all of our bleeding work has not shown air in the lines. Truck was previously drum brakes on back and single pistons on front. Perhaps the stock master cylinder does not supply enough juice for the new brake set up with enough juice? Anyone have a similar setup and running the stock MC? Anyone run into a similar issue? Out of ideas and looking for suggestions.

Dave
 

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Hey everyone! Need some insight on a brake issue.

Did the front brake blazer upgrade on my 2000 S10 pickup and added an LSMFG disk brakes kit on my 8.8 in the rear. Been trying to get my brakes bled for the past few weeks and have not been successful. We tried the following:

1. Conventional bleeding and gravity bleeding procedures countless times
2. Replacing the brake booster and master cylinder (stock s10) and bench bleeding the master cylinder
3. Teflon taped the bleeders for possible fitment issues
4. Vacuum bled with a bleeder pump
5. Cycled the abs module multiple times with a scanner
6. Replaced all the break lines on the rear end and checked every point for leaks with soapy water.

Pedal is still spongy. It gets hardish after a few pumps but goes softer when it sits. All data suggests a leak or air in the system somewhere but all of our bleeding work has not shown air in the lines. Truck was previously drum brakes on back and single pistons on front. Perhaps the stock master cylinder does not supply enough juice for the new brake set up with enough juice? Anyone have a similar setup and running the stock MC? Anyone run into a similar issue? Out of ideas and looking for suggestions.

Dave
After you cycled the abs, did you bleed the system again?
 
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The most common problem with bleeding rear brakes on an S10 is the size of the line and the distance to the rearend. When you have it apart all that fluid drains out. When you refill it a lot of air gets trapped. The trick would've been to plug the line while it was apart to prevent that. I just swapped my rearend for an 8.5. After years of fighting rear bleeding problems I put plastic plugs into the tee at the differential cover. Once I got the rearend in and everything connected I removed the plugs one at a time and connected the right and left lines from the calipers. I opened the bleeders one at a time and after 5 minutes of gravity bleeding I had a solid pedal. Just to be sure I did the 2 man pump and push routine and did get a couple tiny bubbles from each side.
Since your lines were drained the sure way to bleed them is to bite the bullet and buy a pressure bleeder.
I use a Motive Products p/n 108 for most 1992-2010 GM vehicles with the round cap.
Currently Walmart has the best deal @ $65. It's shipped from Motive Products for free. If you order on Motive's site they charge $17 shipping. For the same item.
350790
 
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Discussion Starter · #6 ·
The most common problem with bleeding rear brakes on an S10 is the size of the line and the distance to the rearend. When you have it apart all that fluid drains out. When you refill it a lot of air gets trapped. The trick would've been to plug the line while it was apart to prevent that. I just swapped my rearend for an 8.5. After years of fighting rear bleeding problems I put plastic plugs into the tee at the differential cover. Once I got the rearend in and everything connected I removed the plugs one at a time and connected the right and left lines from the calipers. I opened the bleeders one at a time and after 5 minutes of gravity bleeding I had a solid pedal. Just to be sure I did the 2 man pump and push routine and did get a couple tiny bubbles from each side.
Since your lines were drained the sure way to bleed them is to bite the bullet and buy a pressure bleeder.
I use a Motive Products p/n 108 for most 1992-2010 GM vehicles with the round cap.
Currently Walmart has the best deal @ $65. It's shipped from Motive Products for free. If you order on Motive's site they charge $17 shipping. For the same item.
View attachment 350790
Would this still be the case if we crimped the lines to keep fluid from pouring out?
 

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I built a pressure bleeder using a garden sprayer and a part off ebay to clamp the reservoir, but for $65 that kit is pretty legit. Pressure bleeding has been my go-to method and never failed me.

If you squeezed a hose shut and it caused internal damage, it usually results in a flow restriction making the pedal harder to press and causing the brake to drag until the fluid slowly goes back into the master.

The brake bleeder screws bottom out on a tapered seat to seal the fluid. The teflon tape isn't needed, but it does help with vacuum bleeding though, I'd always get bubbles from air going past the threads and I never felt comfortable with the job.

You can try to double check the master is bled by having someone pump and hold the pedal down while you crack the lines on the master one by one. This solved the problem for me on a Buick, air was trapped at the end of the master and cracking the front line got it out.

I also like to tap on some parts while brake fluid is being pushed around, like the rear calipers on any car with an integrated parking brake. I'll tape all over the caliper with my wrench to try and dislodge any air bubbles.
 

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You might find temporarily installing caps (metal caps which provide a positive seal) at various points of the hydraulic system can be helpful in diagnosis. First remove the lines from the master cylinder and cap the ports. Check to see if the pedal feels solid with very little travel. If OK, reconnect the lines and cap the output of the ABS modulator. If the pedal feels good, keep moving downstream and test each wheel. If the pedal is soft with the ABS modulator plugged you know there is air in the modulator or lines to the modulator.
Also, remember bad brake hoses can swell under pressure and result in low pedal.
Make sure your brakes are in good mechanical condition, i.e. pads and guide pins are free to move as designed. Once, I chased a low pedal problem only to find the pads were so stuck they would flex with brakes applied, then "unflex" with pedal released, pushing the piston back into the caliper.
Finally, I agree with Cruisin S10 about tapping on the calipers to dislodge stuck air bubbles, although I use a rubber mallet. I have uncovered some trapped air by tapping on the calipers.
 

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Take a long clear tube and attach it to the bleeder. Put the other end of the tube in a container so the highest point of the tube is above the master cylinder. I usually go over the fender and set the container in the truck bed. Open the bleeder and slowly pump the pedal until all the bubbles in the tube are gone. Keep a close eye on the fluid in the master, you don't want to let it empty. Then do the next wheel. It also works to just leave the bleeder open overnight. Over night method you could do all four wheels at once.
 

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Hey everyone! Need some insight on a brake issue.

Did the front brake blazer upgrade on my 2000 S10 pickup and added an LSMFG disk brakes kit on my 8.8 in the rear. Been trying to get my brakes bled for the past few weeks and have not been successful. We tried the following:

1. Conventional bleeding and gravity bleeding procedures countless times
2. Replacing the brake booster and master cylinder (stock s10) and bench bleeding the master cylinder
3. Teflon taped the bleeders for possible fitment issues
4. Vacuum bled with a bleeder pump
5. Cycled the abs module multiple times with a scanner
6. Replaced all the break lines on the rear end and checked every point for leaks with soapy water.

Pedal is still spongy. It gets hardish after a few pumps but goes softer when it sits. All data suggests a leak or air in the system somewhere but all of our bleeding work has not shown air in the lines. Truck was previously drum brakes on back and single pistons on front. Perhaps the stock master cylinder does not supply enough juice for the new brake set up with enough juice? Anyone have a similar setup and running the stock MC? Anyone run into a similar issue? Out of ideas and looking for suggestions.

Dave
Definition of fiasco with S10 brakes is as follows.

About 5 years ago I had a 99 S10. A friend worked at NTB and I always got my oil change done there. He was a manager and I got some great prices. Well one Friday morning I stopped in for an oil change. Went to leave and brakes went to the floor. The minion that changed the oil said it did that that to him too... Uh, hello...
So they put the truck in the bay and 12 hours later, I get to go home with new break lines all the way around, new master cylinder, etc.. $900 and my buddy wrote it up as a warranty replacement... Lol...

It took the tools 6 hours to figure out that their scanner tool could communicate with the ABS module to do an auto purge of the break system.

In hindsight, I bought that 99 S10 and my current 02 S10 off of that buddy... Hmmmmmm
 
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