No brakes - leaking brake fluid

[terry23]

I just took my 73 Super out of storage in my garage and went for a test run and no brakes. The pedal hit the floor.
Checking showed no drips under the car but repeated pumping created some fluid spray forward of the master cylinder and a big puddle under the car at the rear coming out of the drain hole ahead of the engine. All wheel cylinders are new and no visible leaks around wheels or brake lines. Master cylinder appears damp but line connections show no leaks.
Any suggestions?

[FJCamper]

Hi Terry23,

By your description, you probably have a bad leak from the front seal of the master cylinder. It can leak around the front m/c seal inside the bulkhead, right into the floorpan tunnel -- and then out the floorpan drain hole near the transaxle.

If you're pulling the master cylinder yourself, remember to be careful of the bulkhead spacers the two m/c bolts run through. They can shift or drop.

FJC

[terry23]

I have determined that the rear partition in the brake fluid resevoir is where the fluid is coming from as the front one is full.
I also see a small amount of fluid under the floor mat where the brake line goes through the firewall. No fluid back of that to the rear.
I pumped the brakes again and it looks like more fluid coming from the push rod area and again from the drain hole at the rear. Spinning the front wheels, the brake pedal will stop them. I wrapped a paper towel around the master cylinder and no sign of fluid there.
Is this consistent with your suggestion?

[Marc]

Rear circuit of the M/C is leaking externally. Doesn't sound like the main brake line is bad. They usually rust out where they snake around the pedal cluster, wetting that area - but since fluid's coming out of the tunnel the M/C is the problem. There's a little weep hole in the rubber bellows that lets fluid enter the void between the inner & outer firewall sheetmetal, from there it gets into the tunnel and ends up leaking back by the trans mount.
Do lift up the floormat and take a good look at the brake line, if it's got more than surface rust you may as well replace it at the same time you do the M/C...if it's borderline it may blow the first time you big-leg the brakes with a new healthy M/C.
Also, you should pick up some of the special blue brake hose for the feed lines and replace at least the two bits nearest to the M/C - used hose often won't seal perfectly on the new M/C inlet nipples, leaving you with a slow fluid leak.
Do not get DOT5 (silicon) fluid. DOT3, 4, or 5.1 are all OK.

[SCOTTRODS]

Also, Don't assume that the brake line is not damaged or rusted through. I had one bust in between the two walls of the bulkhead one time..... I thought it was the MC as well.... Checked it later with compressed air after the fluid all leaked out, and found a small hole had been rubbed in the line INSIDE the edge of the bulkhead grommet. See picture: (yeah, I know it's probably not the right year model, but illustrates the point really well.

[Marc]

...I had one bust in between the two walls of the bulkhead one time..... I thought it was the MC as well.... Checked it later with compressed air after the fluid all leaked out, and found a small hole had been rubbed in the line INSIDE the edge of the bulkhead grommet...

Interesting. I've never seen that but it certainly would give similar symptoms. If the inside of the M/C boot is dry and the outside is wet, a break there in the pipe would be the only possibility.
Shouldn't be possible with a factory-installed pipe but if some hack replaced it and left it rubbing on steel that could happen...

[terry23]

Inside of boot was not dry so assume MC is leaking. Have taken it out and will have to get it fixed or a new one. This was new when I rebuilt the car and has only 3000 miles on it. What are all the codes at the end of the MC part number? BHGR, BHX, DBR, BD, HBR, BH?

[Marc]

The VW part number for all LHD Super M/Cs is 113 611 015BH. 113 611 015BD is for a Standard Beetle. All of the other alphabet-soup suffixes are created by aftermarket parts-sellers for their use in identifying where the part came from...BHGR=Germany, BHBZ=Brazil, etc...don't try to read much into anything beyond the first two letters, since they don't all use the same system.
Brazilian-made TRW and Varga are generally considered to be the best value for dollar, while German FAG and Ate are the best quality when price is no object (they were OEM suppliers to VW of Germany). Jury's not in yet on the aftermarket German FTE brand. If no mention of the manufacture is made, it's probably Chinese (KMM, for example). Some sellers use X for rebuilt, some use it for China or other third-world maker.

[terry23]

Have replaced the master cylinder after bench bleeding, reinstalled and bled the brakes. Still have only half a pedal. Is there still a problem or does the push rod need to be lengthened? I dont have any leaks anymore.

[Marc]

Ordinarily the pushrod is adjusted once at the factory. The correct procedure is to set the pedal stop so there's 1mm of freeplay at the pushrod (~¼" at the pedal). If that requires that the pedal be closer than 8" from the firewall, the pushrod should be lengthened - but always maintain that 1mm of freeplay, the brakes may seem better with out it but the pistons in the M/C won't come all the way back when you take your foot off the pedal, so the compensating ports remain closed and fluid can't relieve back to the reservoir as it heats & expands. After a short drive your brakelights are stuck on and the brakes are dragging.
How did the bleeding go? Nice solid streams of fluid at all four corners? Check that the adjuster screws are all right-side-up (the slots are angled and the angle must match that of the end of the shoes) and adjust the brakes. Back off the e-brake cables before you adjust the rears, if they're too tight you can't get a proper adjustment and the forward shoes will wear out rapidly.