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1978 Spider
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Discussion Starter #1
started investigating why the power brakes didn't work on my new car...first step is usually to pull the engine vacuum supply hose to the booster and verify presence of vacuum....

well got plenty of vacuum...but for some reason a PO decided to plug the vacuum valve on the booster...with a WIRE NUT and silicone ?????

My initial instinct was to remove the offending wire nut and re-attach the booster hose....but then I decided against that...for some reason this was done...before I open a can of worms and possibly unintended consequences...does anyone want to venture a guess as to WHY this was done?

Another Alfa guy in town just replaced his booster. it was full on brake fluid so I guess the MC seal failed and leaked into the booster chamber. Maybe something similar is or had happened here and the PO was trying to prevent brake fluid from getting sucked into the engine? IDK :/
 

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Some people like the feel of the brakes without a booster.
But this seems a bit odd lol
 

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But Mad North-Northwest
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If I had to guess I'd say the booster had failed internally and was leaking. This will cause a vacuum leak and mess up running. Rather than replace the booster, PO just plugged it.
 

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1978 Spider
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Discussion Starter #4
There was a bunch of included assorted parts and stuff with the car...One was a used brake booster still sealed in the shipping box. I would say it was purchased a few years ago. The car has apparently sat mostly idle for several years. But strange this was never installed.

Guess I'll remove the plug and attach the hose this afternoon and see what "happens" or doesn't happen.

I don't suppose they make a rebuild kit for the ATE boosters?
 

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Discussion Starter #6
Vicks had the ATEs for about 150ish last I checked...but if that used one in the box is any good will be going that route first.
 

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Another Alfa guy in town just replaced his booster. it was full on brake fluid so I guess the MC seal failed and leaked into the booster chamber. Maybe something similar is or had happened here and the PO was trying to prevent brake fluid from getting sucked into the engine?
Yes, a failing MC will definitely pass brake fluid into the vacuum booster. That's pretty common on hanging pedal Alfas. Rebuilding or replacing the MC is the proper fix, but I guess a cowboy solution might be to disconnect the vacuum connection to the booster.

But the joke here is that if someone did disconnect the vacuum, they should have plugged the hose that connects to the intake manifold - not the booster! There is no pressure or vacuum in the booster that needs to be sealed. Was the hose plugged too? If not, your engine would have had a massive vacuum leak.

Boosters can fail when they get exposed to brake fluid. But they don't fail immediately, so your existing booster may still be OK. You can re-connect the vacuum hose and see if the pedal feel changes. If the booster does work, you should monitor the brake fluid level closely, and make sure that the float on the reservoir is working so it will signal you if the fluid level drops.
 

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agree,
just join a hose between that and the intake...see what happens....worst case a bit of oil enters the intake and a plume of white smoke comes out the exhaust
Best case, you now have boostred brakes:)
 

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the other thing that can happen is the booster locks or jams basically locking the brakes. ask me how I know.

cheers
 

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None of the new boosters available today are original ATE's. There all aftermarket.
 

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Discussion Starter #12 (Edited)
The hose was not plugged. It pulls strong vacuum from the engine. I did remove the plug and re-attach the hose. The idle is off/rough with the hose connected to the booster but not as bad as the hose just pulled off and left open. I stepped on the brakes and they still feel hard. I didn't try driving it though. Plugging the hose with my thumb and idle returns to normal. So the booster is leaking. Then I did the stupid mistake of re-inserting the wire nut plug which was previously glued in with silicone. Free of the silicone bond, the vacuum hose sucked the wire nut down the hose...so now I must fish it out...it only went a couple inches before jamming.

The "extra" parts booster that came with the car...I can blow thru the hose fitting and air comes out the MC mounting hole (finger pointing in first picture). Either this booster is leaking as well or is there supposed to be a gasket that seals the MC to the booster? It's been a long time since I last replaced an MC or booster on any car.

Also..the position of the hose fitting on the booster pictures (not the on currently on the car)...it will only rotate to point between straight down or towards the drivers fender. Only 90' of movement. I don't want to force it to point towards the engine and booster hose and break anything.
 

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Discussion Starter #14
None of the new boosters available today are original ATE's. There all aftermarket.
Well as long as they fit the application correctly. But the 70s & 80s US market spiders were the ATE one originally?
 

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Discussion Starter #15
The MC seals that hole with a rubber ring.
So the booster is a big vacuum chamber? I've never took one apart or actually understood how they work...other than they require vacuum to somehow "boost" the resultant hydraulic pressure. google shall be my friend...lol
 

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the elbow basically turns about 1/4 turn (maybe half) then you should be able to wiggle it right out, then put it back pointing the correct way....it does not turn round 'n round;)
here is what it looks like, so you get the idea.
ate connector.jpg
 

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Discussion Starter #17
OK...I'll work on getting it out. I guess the used "donor" booster came off a different model alfa?

Anything I need to be prepared for during the R&R? I've heard of a pin or shaft that can break in the pedal cluster?
 

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But Mad North-Northwest
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Easiest way to do this job is to pull the whole pedal box, IMO. You need to bleed the brakes and clutch after, but it makes the overall job much easier. As you noted, if you have an original clutch lever this is also a really good time to replace it with an uprated version, as the original will fail on you at some point.


Disconnect the three brake MC tubes and the clutch MC tube. Remove the brake and clutch pedal covers. Two nuts in the engine bay, and two nuts in the driver's footwell, and possibly one bolt in the engine bay by the clutch MC, and the whole pedal box comes out with a bit of lifting and rotating.

When reinstalling, thread the nuts on the hydraulic tubes into place by hand. Do the clutch tube before you tighten up the pedal box and the brake tubes before you attach the MC to the booster. This makes it a lot easier to get them lined up and avoids potential cross-threading.
 

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You can undo the mounting bolts fro the master cylinders and move them out of the way without undoing the lines.
 

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But Mad North-Northwest
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Right, but getting to the booster bolts under the dash is a real PITA. Easiest to just take everything out of the car in my experience, especially if you take the opportunity to replace the clutch pivot shaft.
 
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