Hi all, i am new to the board and it was recommended by a very good friend. I have a 1972 p1800 E. I just finished rebuilding the master cylinder, calipers and new pads. When everything was reinstalled, the front half (rear) was not pushing any fluid. Any thoughts?

Jeff;

Welcome to this forum!

Remote troubleshooting without lots more details is tough...what makes you say one system is not working?? Did you check for pumping fluid at Master Cyl or Caliper? (Swollen shut, old brakelines are not unheard of!) If one sys is really not pumping fluid at Master, it sounds like something did not go right in the rebuild...

Also, I presume you are aware of the dual diagonal systems, and the pressure differential sensing Switch under the Hood, which needs to be reset when bleeding (see manual for bleeding order* and info on Press Diff Sw).

Also, left and Right Calipers of dual diag systems can be inadvertently swapped, putting two of the bleeding Nipples low, and making it impossible to remove all air...beware of this, and don't be fooled!

* I recall some differences in the bleeding order for the dual diag systems...it's important to RTFM for your model year on this!

Good Hunting!

Hello and welcome to the board.

Since you are new, I have no idea what your skill level is, so please don't take the following as insult. But when it comes to brakes, you need to be REALLY sure you know what you are doing. Your safety and the safety of the public could be at stake.

Did you split the calipers when you rebuilt them and possibly mix the parts?
Did you reassemble the brake master components correctly and without damaging the seals?
Did you bench bleed the brake master?
Did you bleed the brakes in the proper sequence?

And not that it should affect your bleeding of the brakes, but did you remove the single wire switch in the junction block right after the brake master? This switch triggers a light on the dash when you loose a brake circuit and can be damaged by the moving parts inside the junction block while you are bleeding the brakes. So it should be removed before bleeding and then re-installed when you're done bleeding the brakes.

I own a repair shop specializing in rear wheel drive Volvos with an emphasis on the pre-1976 Volvos and I am extremely familiar with the brakes on your car.

At this point in time, the only brake part I routinely rebuild are the brake proportioning valves that are used on your car and that's because I can get repair kits and because they are very easy(for me) to rebuild. Almost all other hydraulic brake components I sell and use are either new or rebuilt by a bonded rebuilder.

I used to rebuild calipers myself, but that ended when the cost of my rebuilds started to far exceed what I could buy from a rebuilder. This was mostly due to my insistence on using only Volvo or OEM(Original Equipment Manufacturer) parts. For example, just the cost of the replacement pistons from Volvo was higher than my cost for a complete rebuilt caliper that also included new brake pad hardware!! So with the combination of cheaper costs for my customers and the elimination of my liability for the rebuilt brake parts, remember I own a business, most of my rebuilt brake components are now done by outside bonded rebuilders.

In the last 10 years, just about all of my suppliers no longer have nice cores to rebuild, so they don't always have rebuilt units in stock.

So I started sending out my own cores in advance so I can service my customers quicker because the turn around time for rebuilding can take over a week for calipers and even longer for most of the rebuilt brake boosters.

I hate to admit this, but if you needed a set of rebuilt calipers, I don't have them in stock right now as I recently sold all 4 calipers to a customer and haven't sent in a fresh set of rebuildable cores yet.

Please feel free to ask questions.
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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com

Thank you for the response and your time. 30+ years ago i was certified as a mechanic by a local community college program. I was tired of taking my car to other people that i felt didnt do right by me. This project has been a complete rebuild of the 72 that was once my wifes car and was garage kept for over 26 years without so much as opening the door. I have rebuilt all ancillary systems of the car and the brakes were the last. I had never run into this issue when rebuilding other master cylinders but must admit that I have less than half a dozen under my belt. The master cylinder front chamber(rear set of calipers) doesnt move so much as a puff of air even with the bleed nipples removed. I had lost my bench bleed kit over the years so thought i could bleed it after install. Upon inspection, calipers appear to be functional and have no leaks or problems with the o rings. My only thought is that something in the reservoir may have blocked one of the ports on the MC? If i need to go with a new MC, do you have those in stock?
Thanks
Jeff

I know it can be very difficult to find a competent mechanic. And if you live in a small town, your choices can be very limited.

I have a customer who is the older sister of a childhood friend. She now lives in a small town very near the California/Oregon border and they have only 1 repair shop in town and because she doesn't trust him, she uses a shop in a nearby city for basic repairs like oil changes, but drives her car, not a Volvo, down to my shop in the LA area for any major repairs.

Yes, I have new brake masters in stock, but before you buy 1, try "bench bleeding" in the following manner which can be done with the brake master mounted on the booster.

1st prepare the area under the brake master with rags to absorb the brake fluid that will leak. You may want to be able to rinse the area with water after you are done, so have a garden hose or supply of water in case you are worried about the paint on the inner fender.

Disconnect both brake lines from the brake master and use a finger from each hand to cover the ports while someone SLOWLY depresses and releases the brake pedal. Try to control the direction of the fluid like you might do when you don't have nozzle on your garden hose, or you'll squirt fluid all over the place and try to seal each port as the pedal is being released to help prevent air from being sucked back in.

And speaking of fluid, Volvo recommended DOT 4 fluid. DOT 3 will not immediately cause problems, but if you are using DOT 3, you can easily flush it out with DOT 4 while you're bleeding the brakes.

If you could find "inverted flare" male plugs and they are hard for me to find, you could verify your rebuild. When properly bench bled and with flare plugs installed in the brake master, the brake pedal should be rock hard.

Good luck.

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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502

.

Thanks Eric, I have installed a new Master Cylinder and passenger sided rear caliper as the bleeder nipple broke off. Nothing i did would loosen the broken piece so i had to replace it. I have bench bled the master cylinder and that is working fine ( i think i messed something up with the rebuilt one). So now that i am attempting to bleed the system, I am getting nothing. I am able to maintain 25 lbs of vacuum pressure with no draw from the master cylinder. So I am not sure if the lines are clogged, if so how to unclog them. It is my understanding that there is a pressure regulator of sorts directly below the master cylinder that needs to be reset but without an owners manual I am not sure how to accomplish this. So again stuck in park for now. If you have any leads on where to get a manual i would appreciate them.

Jeff

Not that it would affect the bleeding, but it is recommended to remove the brake warning switch in the distribution block that the 2 brake lines from the master cylinder go directly to. If you don't removed the switch, you can damage the switch while bleeding the brakes.

There are brake pressure limiters(proportioning valves) for the 2 rear calipers mounted under the car and the 2 brake flex lines screw directly into them.

The proportioning valves can be stuck or clogged and/or the rear brake hoses could be bad, both of which can cause bleeding problems.
--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com