Befuddled with bleeding brakes on grandpa's '90 Volvo 240

Rufblackbird · 03-06-2009, 08:30 PM

Is there a special trick to this? I put in a new master cylinder, and attempted to bleed the brakes, but the pedal is still soft. Bled it again, same outcome. These two times were with an assistant doing the pumping and holding. Read online to try drive it a bit, maybe it'll dislodge an air bubble so I did that. Then bought the Motive pressure bleeder, and tried bleeding it again to no avail. As a last resort I tried draining all the fluid out, pressurized the system with the motive, then cracked open each bleeder valve until all the fluid came out. Then I filled it up with DOT4, and pressurized the system with brake fluid. As fluid came out of each bleeder I closed it, then when they were all done I had an assistant pump and hold while I bled each caliper. STILL mushy/spongy brakes. I am soooo stumped right now...anyone had one of these cars before and had the same problem? Been stuck on this for the past three days...

Thanks in advance!!

pwd72s · 03-06-2009, 09:50 PM

Guessing here...is there a way to have the new master cyl. full before install? You might also try one RoninLB told me about...let gravity do the bleeding, one corner at a time, just let the fluid slowly drip out, being sure to keep the reservoir full...

I'll send Ron a link.

RoninLB · 03-06-2009, 10:25 PM

no experience with Volvos so only a wild guess

See if you have a rear brake proportioning valve. If so they sometimes can make you nuts trying to bleed. More if a yes.

Did you install the pads loose to the pistons or you jammed them in tight?

Sounds like the helper didn't have a situation where he had to pump the pedal to get a higher pedal?

I also assume you didn't see any air bubbles?

nota · 03-06-2009, 10:57 PM

bench bleed the M/C BEFORE you do the lines?
if you didnot get the air all out of the M/C it never will get a hard pedal

DOES THE 90 HAVE ANTI-LOCK ?

Rufblackbird · 03-06-2009, 11:11 PM

thanks Paul...

bench bled the master before I installed it, and didn't touch anything else (pads, calipers, rotors are all untouched). No rear proportioning valve, though there are two pressure regulating valves that reduces hydraulic pressure to rear brakes to help prevent rear wheel lock up under hard braking (this is according to the Bentley manual). I tried knocking them with a rubber mallet while bleeding, and didn't do anything. No air bubbles visible anywhere...

was gonna try the gravity feed one, but thought I'd do it one better and put some pressure (motive bleeder) through it, and that was my last resort. Now I'm stuck.

I've done many cars before without bench bleeding the master first, and they've always had a hard pedal in the end. But this one I actually did bench bleed...

Car does not have ABS.

thanks all!

johnco · 03-07-2009, 12:44 AM

I've been going thru this with 3 cars recently with rear drum brakes. with a Toyota and my 62 Oldsmobile, adjusting the rear shoes gave me brakes at last. With a 61 Buick I've been fighting for weeks, we finally discovered last night the rear shoes were contacting drum with only about 1.5-2 inch of the pad with both shoes. I'll be pulling drums off tomorrow to have them turned down. we had replaced/upgraded to modern power m/c, bled each wheel a dozen times, bench bled m/c again, and bled each wheel several times more and still had spongy brakes.

Rufblackbird · 03-07-2009, 01:26 AM

I wish that were the problem...only thing is the car's got 4 wheel disc brakes...

cantdrv55 · 03-07-2009, 07:04 AM

Have you asked these guys?

http://www.brickboard.com/

lm6y · 03-07-2009, 07:07 AM

Sounds like a bad Master cylinder. I used to have a set of plugs just for times like this. Plug the M/C, eliminating the rest of the system, and check for a pedal, if you have a consistent pedal, it's further down the line. No pedal, or soft, it's the M/C. Sometimes quality control isn't what it's cracked up to be.

What was the original problem before you changed the M/C ?

Is the booster O.K.? I've seen them fail, and apply vacuum to the rear seal on a M/C causing it to fail also. The sysmptoms are pretty close to what you describe. If your lucky, it will leave a trail down the front of the booster.

If it isn't that, I got nuthin".

Rufblackbird · 03-07-2009, 10:57 AM

haven't checked the brickboard...but did ask a friend of mine that used to work at Volvo. Unfortunately he didn't have any special tips...

original problem...wasn't a problem. The car needed its brakes bled as it appeared it hasn't been touched for years (black and murky fluid). During the pumping process it lost pressure all of a sudden, and after taking the nuts off the master it was rusty inside so it was replaced.

booster seems ok...if I hold the brakes down and start the engine, the pedal will go down further.

fastfredracing · 03-07-2009, 12:28 PM

Did you start with the wheel farthest from the master cyl??. You may have to let some air back into the front brakes, till they get soft again, and then bleed the hell out of the right rear, left rear, and move on to the front right , front left etc.. I have had quite a few cars in the past that just were a sob to bleed.
It is also possible that the caliper slides are frozen, and not allowing the front side of the caliper to meet with the rotor, so the piston comes way out hits the rotor, and when you let off of the pedal, it retracts, and takes a whole of pedal to bring it back into contact with the rotor. Is your pedal firm but low, or is it actually spongy and soft??. Also there may be an adjustable rod that connects the booster to the master. If you get a firm pedal that is low, and all else seems o.k. you can try to lengthen the rod a little bit( not absoutely sure if your volvo has this )

lm6y · 03-07-2009, 08:03 PM

What do the rubber lines look like? Are they soft and spongy? I've seen old ones swell with pressure.

Any of the old steel lines rusty, and seeping?

Just throwing out ideas here..........

Rufblackbird · 03-07-2009, 11:29 PM

started with the one farthest, so RR, LR, RF, LF. Then looked through the Bentley manual and it had some other sequence so I did that as well. No difference. Pedal is spongy and soft, not low and firm. Finally got my air compressor hooked up tonight, so tomorrow i'm draining all the fluids and removing/cleaning the bleeder valves, running some denatured alcohol through the system, and blow it through with some compressed air. Then start the whole process again. Hopefully this will be it.

Lines are all steel, at least the ones going to the calipers. Not rusty at all. Car has ~103k miles and gramps has owned it since '91. It's the cleanest 18 year old daily (well, maybe every other day) driver that I've seen.

RoninLB · 03-07-2009, 11:42 PM

Quote:

Originally Posted by Rufblackbird

No rear proportioning valve, though there are two pressure regulating valves that reduces hydraulic pressure to rear brakes to help prevent rear wheel lock up under hard braking

. No air bubbles visible anywhere...

was gonna try the gravity feed one, but thought I'd do it one better and put some pressure (motive bleeder) through it, and that was my last resort. Now I'm stuck.

Car does not have ABS.

another guess

any device in the lines may be trapping air especially if using psi or pedal pump bleeding.

if my problem I'd start with pulling brake pads. I'd file the leading edge leading into the caliper so I could extend the pistons out from the calipers far enough so I'd have to force the pads into the caliper. Tight enough so that I'd need a rubber/whatever hammer to get them in.

If still a problem I'd start bleeding before and then after any device in the system.

I'd only do gravity bleeding at this point to prevent any unintended consequences.

I assume the pedal can't be pumped into a hard pedal, right ?

Rufblackbird · 03-08-2009, 12:07 AM

I was gonna take out all the pads and push the pistons back in as well, but never got to it today. Tried hammering each caliper with a rubber mallet to see if any air bubbles will come out, and nothing happened. Will try the gravity bleed after I get the lines dry.

nope, pedal can't be pumped into a hard pedal. It'd get a bit harder, but not by much.

RoninLB · 03-08-2009, 12:28 AM

Quote:

Originally Posted by Rufblackbird

I was gonna take out all the pads and push the pistons back in as well,

I was suggesting installing the pads very tight with the pistons out as far as possible to allow pounding the pads in

I hate crap like this

mattdavis11 · 03-08-2009, 06:25 AM

+1 to lm6y's comment about the master being bad. It wouldn't be the first I've seen or heard that was bad straight out of the box.

Jandrews · 03-08-2009, 07:15 AM

Silly question, but just trying to throw stuff out there...

It's not like our early 911 front calipers is it, where they have an inner and an outer bleeder? I.e. two bleeders on each caliper? That'll make a monkey out of an unsuspecting brake jobber!

JA

Rufblackbird · 03-08-2009, 07:25 PM

Quote:

Originally Posted by Jandrews

Silly question, but just trying to throw stuff out there...

It's not like our early 911 front calipers is it, where they have an inner and an outer bleeder? I.e. two bleeders on each caliper? That'll make a monkey out of an unsuspecting brake jobber!

JA

actually, no, it's got three bleeders on each of the front 4 pot calipers. I was like WTF this thing has 4 piston calipers?!?!?!

anyway, finally solved the mystery today after a long struggle. Had my assistant step on the brakes and then I tried to turn each rotor by hand. Sure enough, the right rear wasn't holding. So I yanked off the caliper and shot brake cleaner through the bleeder screw hole and blew out whatever could be stuck inside. This seemed to work, as the pedal hardened up almost immediately...this is one of the reasons why you should flush your brake fluid regularly, before it turns black and full of crap!

thanks to those who chimed in!

pwd72s · 03-08-2009, 07:30 PM

I love a happy ending...