Today I attempted to bench bleed a rebuilt master cylinder
before installing and had one circuit that just never ran out of air.
It was the line at the far end of the cylinder.
I opted to return the cylinder to the local parts place.

Does anyone have a clue regarding bench bleeding, and the best way to
reintall with the least PIA?

Bill

I like Tony's solution.

For the record, I had better luck bleeding my 245's brakes (after I foolishly let the MC empty while replacing the calipers) with the rear end a fair amount higher than the front... I also used a Motive power bleeder. Have someone pump the brakes a few times while pressurized and bleeding, That should hopefully get the air out of the MC.

Good luck!
-Ryan

--

Athens, Ohio
1987 245 DL 314k, Dog-mobile
1990 245 DL 134k M47, E-codes, GT Sway Bars
1991 745 GL 300k, Regina, 23/21mm Turbo Sway Bars

I Bench Bleed in the car. I just did a new Master on my sons car Sunday (not a volvo).


I bolt the Master to the firewall.
With these Plugs with rubber hoses attached to them that screw into the Master( I got them with a Master cylinder on time and held onto it.
I fill the reservoir run the rubber hose into the reservoir and Pump the brakes.
Do not bottom out the Brake pedal and do not pump hard. Within 5-10 pumps on the pedal you should be good to go.

Now have someone hold the brake pedal down Slighty as you unscrew the Rubber hoses and screw in the Steel Lines. If you only had Master Cylinder issues and you just took the steel lines off, no air got in the steel lines and you shouldn't have to bleed the rest of teh system

Did you get any "Bleeding system" in with teh new Master?
--
'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.no.net/ebrox/Tony's%20cars.htm

Thanks,
I'll get another rebuilt M/C tomorrow. Some comments on the Brickboard archives
indicate horrible luck with rebuilt master cylinders. I'll find out soon
I'll be interested to see what action there is at the front girling brake bleeders, since before, one of the lines seemed to bleed out with less pressure.
Maybe a fault of the original M/C.

Bill

Bill, This is exactly like the Bleeder I was talking about.

You put a piece of hose on each Fitting, Screw the fittings into the Master. You don't need that little clip in center of picture, that was for holding the Hoses down into the resevoir on the old style american Masters. Pump away unit the bubbles are gone.

http://www.shop.com/+-a-Master+cylinder+Bleeder+fittings-p81990651-k36-t2-st.shtml
--
'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.no.net/ebrox/Tony's%20cars.htm

I looked at that bleeder kit, They need clear tubing to see what's up,
and who knows if they have 4 adapters for the volvo M/C ?

Now I have the tubing and 4 cheesy plastic adapters from the rebuilder.

I'll grab a set of brake lines from a boneyard M/C
(Plan B would be to buy two shorty volvo brake lines and cut 'em in half)

hopefully this rebuilt won't die too soon, it has a lifetime warranty
but I'm still considering returning it for a refund. Whoever said rebuilt cylinders are junk, must know something. Maybe you want "remanufactured"?

"I looked at that bleeder kit, They need clear tubing to see what's up,
and who knows if they have 4 adapters for the volvo M/C ?"

Why 4 adapters?

The Volvo Brake manual shows only 2 active output lines for any MC from '88 on, whether ABS or not. And clear tubing is not essential—you can watch for bubbles in the reservoir.

The picture below is a 240 Ate MC, using short lengths of "auto store" hard line formed to fit (and European ISO bubble flared), but would apply to any MC described in my 700/900 brake "Green Book".

Hi again Lucid (Bruce?)

Whats your email? I'll send you a photo of my M/C with four ports.
I don't know how to attach photos on brickboard messages.

Bill

Yes, 4 adaptors my ATE M/C has four ports,different from your photo,
there's two additional ports on the bottom.
its on an 89 740GL, mfg in Belgium.

I noticed what was happening with the bleeding with the clear tubing
and watched the "air bubble action". There are large and small bubbles
that take varying amounts of time to move. There's lots of friction there.
You can do better with clear tubing.

If I pressed the piston to far it would introduce air- you cant see that
without clear tubing.

Bill

"Yes, 4 adaptors my ATE M/C has four ports,different from your photo,
there's two additional ports on the bottom."

My '93 940 MC also has 4 "ports" but only 2 are connected to the brake system. The other 2 (on fender side) have no lines connected, so they are effectively just plugs that can be ignored. [I don't know what these odd 2 are for.]

My response is also based on the '82-19.. 700/900 brake manual pictures and descriptions, none of which show more than 2 active ports and lines.

Thanks Tony,

Yesterday I got the second rebuilt M/C and had some more trouble
bench bleeding it as follows:
The fittings supplied with the M/C were not good as the threads may
have been a near miss, and the tubing end was too short so the clear
tubing was at risk of falling off, PLUS they only supplied fittings
for two ports.
I found that I continued to get air if I pumped the piston much more that half way, indicating that the deep part of the bore is no good. and that their
rebilding job is perhaps only new seals and the bore is not done right.
This might explain why some comments on the Brickboard that rebuilt M/C's are junk.
I got out all the air easily with short strokes on the piston, then it mounted
fine and I have a stiff brake pedal and good brakes without bleeding.
(I'll bleed each wheel soon after everything settles in the brakelines)

I saw some company that rebuilds master cylinders for vintage cars where they
install a stainless sleeve in the bore. I dont know if they can do the Volvo
with four ports? They guarantee this master cylinder for life.

If this rebuild isn't too pricey then it might be good to get a boneyard M/C
and get it sleeved, plus save the brake lines for bench bleeding?

Maybe someone has some experience here?

Bill

Howdy Bill,

...had one circuit that just never ran out of air.

The most likely source for a never ending supply of air is the fitting where the bleed return line was attached to the master cylinder. If the reservoir was never empty, there was no place for the front bore to pull air from except the bleed line and fitting. With a leak there, every time you relieved pressure on the piston, it would have pulled air into the bore. Because the return line presented a much easier path for the fluid on the pressure stroke, there most likely would not have been any significant weeping past the fitting.

If you had blocked the return line and then pressurized the MC you probably would have seen fluid dripping from the fitting.

...one of the lines seemed to bleed out with less pressure.
Maybe a fault of the original M/C.

The master cylinder applies pressure equally to both sides, both lines. It is not possible for the MC to be the cause of this symptom.

The most likely problem would be an obstruction in the line; rust flake, or dirt. Remove the line in question and clean it with new brake fluid and compressed air. Do not pressurize the line with air while it is attached to the system; it must be open at both ends if you are using air to push the fluid through the lines.

As a matter of fact, on a car that has high miles or has been parked for a long period of time it would be a good idea to flush the entire system.
--
Mr. Shannon DeWolfe -- I've taken to using mister because my name misleads folks on the WWW. I am a 52 year old fat man. ;-)

Hi Shannon, (and thanks for the input)

Your idea about a bad fitting is interesting since the rebuilt cylinder
came with two fittings and I had to return to the parts place for two more,
and one was iffy. I think I'll get some better fittings from a pair of short brake lines to do the bench bleed thing. I did check to see that the plastic fittings were tight.
I'm concerned that the rebuilt M/C's may not be of high quality.
It shouldn't be a big deal for any machine shop specializing in that business though.
I'll know more tomorrow

Bill