Rear brake fluid reservoir empty - refill? Bleed?

Suspension related stuff goes in here.
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stuartrubin
Posts: 186
Joined: Sun May 24, 2015 11:10 pm
Your car is a: 1975 Fiat 124 Spider
Location: 44122

Rear brake fluid reservoir empty - refill? Bleed?

Postby stuartrubin » Sun May 07, 2017 10:20 am

I just noticed that the rear brake fluid reservoir is completely empty. I don't know how long it's been like this. (The FIAT owners manual tells you to check it every 300 miles!) I'm not sure what to do next.

Intuitively, I'm thinking that if it's empty, just fill it up, but I suspect it's not that simple.

Do I need to bleed the system?

Anything else I need to look out for?

Thanks!

Stuart
Stuart
1975 FIAT 124 Spider
Il Mostro di Frankenstein

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kilrwail
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Joined: Wed Mar 04, 2009 6:49 am
Your car is a: 1978 Fiat 124 Sport Spider
Location: Perth, Ontario

Re: Rear brake fluid reservoir empty - refill? Bleed?

Postby kilrwail » Sun May 07, 2017 11:33 am

Check under the master cylinder for a leak. Also around the rear calipers. There's a good chance you need a new M/C.
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Peter Brownhill

1978 Fiat 124 Sport Spider - original owner
1977 Porsche 911S - track car
2015 Ram 4 x 4 - hauler
PCA National Instructor

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RRoller123
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Joined: Sun Nov 13, 2011 2:04 pm
Your car is a: 1980 FI SPIDER 2000
Location: PLYMOUTH, MA USA
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Re: Rear brake fluid reservoir empty - refill? Bleed?

Postby RRoller123 » Sun May 07, 2017 12:33 pm

+1. That is where mine started leaking. The seal goes on the Master Cylinder, where the plunger from the Vacuum Booster pushes in. Needed a new Master Cylinder. In my case, it ran down the inside of the lower fender and suspension parts and even down the inside of the wheel. Take a look there. It also could be leaking anywhere along the brake line going to the splitter in the rear too, or at either rear brake. Check those spots as well. At any rate, have to fix the leak before refilling and bleeding.
'80 FI Spider 2000 (rolling "resto")
'74 X1/9 (many years ago)
'79 X1/9 (fewer years ago)
'86 Jaguar XJ6 (2nd Hobby Car)
2011 Chevy Malibu (daily driver)
2010 Chevy Silverado 2500HD Ext Cab 4WD/SB
2015 Keystone Montana High Country 343RL

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stuartrubin
Posts: 186
Joined: Sun May 24, 2015 11:10 pm
Your car is a: 1975 Fiat 124 Spider
Location: 44122

Re: Rear brake fluid reservoir empty - refill? Bleed?

Postby stuartrubin » Sun May 07, 2017 11:40 pm

Thanks for the responses. As you said, I guess I have to find the source of the leak first. Here come more stupid questions:

Can I just pour brake fluid in the reservoir, pump the brakes, and look for the drips? Is it that simple?

And even stupider questions:
If the hydraulic brakes are a closed system, and obviously when you actuate the brakes, fluid doesn't squirt back into the reservoirs, how does the fluid flow, when needed, into the master cylinder? What allows the fluid to flow in, but not out?

Thanks for indulging me. I'm the eternal noob here, but I'm trying! (I also don't want to find myself driving with no brakes!)
Stuart
1975 FIAT 124 Spider
Il Mostro di Frankenstein

User avatar
RRoller123
Posts: 6913
Joined: Sun Nov 13, 2011 2:04 pm
Your car is a: 1980 FI SPIDER 2000
Location: PLYMOUTH, MA USA
Contact:

Re: Rear brake fluid reservoir empty - refill? Bleed?

Postby RRoller123 » Mon May 08, 2017 4:58 am

Yes, to your first question, and the fluid volume that actually moves is very small. It can flow back to the reservoir, as evidenced by the air bubbles that flow back in there when it is being primarily filled. It needs to have some small ability to flow somewhere for thermal expansion too.
'80 FI Spider 2000 (rolling "resto")
'74 X1/9 (many years ago)
'79 X1/9 (fewer years ago)
'86 Jaguar XJ6 (2nd Hobby Car)
2011 Chevy Malibu (daily driver)
2010 Chevy Silverado 2500HD Ext Cab 4WD/SB
2015 Keystone Montana High Country 343RL


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