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Discussion Starter · #1 ·
Well bummer. The BC‘s master cylinder failed at $137k miles and 14 years. Ok. Not the best but not unexpected.
Lost the brake booster while 150 miles from home. Exciting but manageable. Sourced a brake booster from local AZone and today pull the fuse box, master cylinder, and pulled the brake booster. Not good finding the brake booster full of dot4 fluid. So….new master cylinder due tomorrow. Rather pleased the brake booster released from firewall without a big fuss as the foam gasket remained entirely on the booster in one piece.
Only wish I still had my Viton o-ring set and the master cylinder would be back in service in moments.
 

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Discussion Starter · #3 ·
It was rather surprising. Brake peddle was all the way up with little play and hard as a rock as one would expect with a well blead std brake system. Heard a hiss under the dash as I pressed the brakes and a minor engine stumble……sucking air??? Leaning out…. Just not right but manageable. With 16 fresh aircraft cylinders filling the trunk and back seat ~26lb ea. and $1500 each. The BC made it home and still yielded 33 mpg in Dallas rush hr traffic. Bumper to bumper @ 30 mph @ 100F for 1-1/2 hr
 

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Heard a hiss under the dash as I pressed the brakes
Yup. A buddy's '03 Monte Carlo SS just did the same. Hissed like a snake. Once they had the booster off they replaced the MS and reservoir just because. I asked him did it take both feet to stop the car? He said he stood on the pedal and it barely stopped the car.
 

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Discussion Starter · #5 ·
It felt like it but I’m sure it was more closely to just the different between power brakes one std breaks without the extra leverage GM puts on std brake cars of the 60s-80s.. remember when power brakes were an option instead of expected?
 

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Yes, I had a 1968 Buick LeSabre, with power drum brakes. If you weren't careful you could put your head thru the windshield. That is because drum brakes are self-actuating and the braking action increases in proportion to the pedal effort. Four wheel drum brakes are not bad brakes. It is their susceptibility to heat fade that makes disc brakes superior to drums. Adding a power booster to drum brakes made them dangerous for the uneducated. In fact, the boost is so incredible they use a large spring inside the booster to give the driver some pedal resistance. That is why when it fails it feels like you need both feet to stop the car. On the other hand, disc brakes are NOT self-actuating so when you have four wheel disc brakes you really NEED a power booster.
 

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Discussion Starter · #7 · (Edited)
Oh it’s nice to have brakes AND AC but now lost the left front low beam….ant it’s not the bulb…poo
So out with the diagrams and verify the rounds. Now just because I removed the under hood fuse box and disconnected all of the connectors under the fuses and moved ALL of the wires…I did get all of the connectors tight again….What could go wrong….besides not having a left side low beam.
ha!

a quick search and Coby7 posted a PDF of head light diagram and a PDF of headlight grounds….copied over to ground location images 3

Rectangle Slope Font Schematic Parallel
 

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Discussion Starter · #10 ·
With the schematics and daylight it was a 5 min fix.
1 verify ground, horn, turn signal…..no turn signal. Good horn—-> good ground !
2 Check fuses….all good on top.
3 Check fuse block connector…..loose bolt securing connector to top of fuse assembly—-> good turn signal. All light work…
Happy camper and the AC still works.
Must say thanks to @Coby7 for posting the schematics in PDF…so much time was lost due to bad image host policy.
BTW with another vacuum blend on brake master cylinder, clutch feels better!
 
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