HELP with bleeding 90 chevy truck brakes

gearpump · 05-01-2008, 11:10 AM

I had a wheel cylinder (passenger rear) leaking. It ran the master cylinder out of fluid, I filled it up, the brakes worked fine. I got home and changed the leaking wheel cylinder, now I have zero brakes. I cannot get the fluid to the wheel cylinder. I tried bleeding the other rear wheel and it would not bleed either. I replaced the new wheel cylinder with another new one. No help. I replaced the master cylinder ( bench bled it before installing ) last night and it still will not bleed at the rear wheels. I have not tried the front calipers but figure it would not bleed either. HELP please.....

**Raylo** · 05-01-2008, 11:46 AM

Don't know why it won't bleed but you might have better luck with the vacuum pump method. Get a Mity-vac or similar with brake bleed kit. Fill the master then draw a vacuum at the wheel cylinder until it runs clear. Make sure you don't run the master dry. You will prob have to stop (shut the bleeder) and refill the master once or twice unless you can get someone to refill it on the fly for you.

gearpump · 05-01-2008, 11:53 AM

I have never heard of a mity vac, where can I get one?

**Raylo** · 05-01-2008, 05:51 PM

Here's one on eBay. Also available at just about any auto parts store.

http://cgi.ebay.com/ebaymotors/Mityv...3286.m20.l1116

**simpswr** · 05-01-2008, 05:56 PM

Did you block the proportioning valve? . . you should be able to buy a little gizmo for that at any auto supply store

**mack1** · 05-01-2008, 06:14 PM

Hi gearpump and welcome to TSF,

Could you give a little more detail about how you were trying to get the back cylinder to blead? Is your master cylinder dual chambered on that year for front and rear brake seperation? When you pump the brake, does fluid level in the back compartment (assuming dual changered) go down a little?

Do you have a friend helping you at the rear wheel while you pump and then hold the brake? His job being to open the bleed valve letting some air out, then retightening it before you pump the brake again? Note that if he don't open the valve far enough to let some air out, you won't ever get it bled. The compressed air in the wheel cylinder will simply push the fluid back up the line making it look like no fluid is going through the rear lines.

Give us all the details you can, and I bet we can help.
Mack1.

05-01-2008, 11:10 AM	#1 (permalink)
gearpump Registered User Join Date: May 2008 Posts: 2 OS: xp	HELP with bleeding 90 chevy truck brakes I had a wheel cylinder (passenger rear) leaking. It ran the master cylinder out of fluid, I filled it up, the brakes worked fine. I got home and changed the leaking wheel cylinder, now I have zero brakes. I cannot get the fluid to the wheel cylinder. I tried bleeding the other rear wheel and it would not bleed either. I replaced the new wheel cylinder with another new one. No help. I replaced the master cylinder ( bench bled it before installing ) last night and it still will not bleed at the rear wheels. I have not tried the front calipers but figure it would not bleed either. HELP please.....

05-01-2008, 11:46 AM	#2 (permalink)
Raylo TSF Enthusiast Join Date: Feb 2006 Location: Maryland, USA Posts: 523 OS: XP Desktop, Vista HP Notebook, XP Notebook	Re: HELP with bleeding 90 chevy truck brakes Don't know why it won't bleed but you might have better luck with the vacuum pump method. Get a Mity-vac or similar with brake bleed kit. Fill the master then draw a vacuum at the wheel cylinder until it runs clear. Make sure you don't run the master dry. You will prob have to stop (shut the bleeder) and refill the master once or twice unless you can get someone to refill it on the fly for you.

05-01-2008, 11:53 AM	#3 (permalink)
gearpump Registered User Join Date: May 2008 Posts: 2 OS: xp	Re: HELP with bleeding 90 chevy truck brakes I have never heard of a mity vac, where can I get one?

05-01-2008, 05:51 PM	#4 (permalink)
Raylo TSF Enthusiast Join Date: Feb 2006 Location: Maryland, USA Posts: 523 OS: XP Desktop, Vista HP Notebook, XP Notebook	Re: HELP with bleeding 90 chevy truck brakes Here's one on eBay. Also available at just about any auto parts store. http://cgi.ebay.com/ebaymotors/Mityv...3286.m20.l1116

05-01-2008, 05:56 PM	#5 (permalink)
simpswr Moderator Hardware Team Join Date: May 2007 Location: Houston, Texas Posts: 12,097 OS: XP, Vista, Win 7	Re: HELP with bleeding 90 chevy truck brakes Did you block the proportioning valve? . . you should be able to buy a little gizmo for that at any auto supply store __________________ Rich MemTest86 \| BenchTest \| Virus/Trojan/Spyware Help How to post a Screen Shot \| PC running slow?

05-01-2008, 06:14 PM	#6 (permalink)
mack1 TSF Articles Team Join Date: Nov 2007 Location: Texarkana, Texas Posts: 1,245 OS: xp sp3 My System	Re: HELP with bleeding 90 chevy truck brakes Hi gearpump and welcome to TSF, Could you give a little more detail about how you were trying to get the back cylinder to blead? Is your master cylinder dual chambered on that year for front and rear brake seperation? When you pump the brake, does fluid level in the back compartment (assuming dual changered) go down a little? Do you have a friend helping you at the rear wheel while you pump and then hold the brake? His job being to open the bleed valve letting some air out, then retightening it before you pump the brake again? Note that if he don't open the valve far enough to let some air out, you won't ever get it bled. The compressed air in the wheel cylinder will simply push the fluid back up the line making it look like no fluid is going through the rear lines. Give us all the details you can, and I bet we can help. Mack1. __________________ "If you like yourself others will like you also" me "Don't drink downstream from the herd" Will Rogers Submit New Articles Here