Hello, my 1984 c4 has a bad problem with the breaks. At first we thought that it just needed to be bled, but as we rode around our town we came to a red light and couldn’t stop whatsoever. Even in neutral the car wouldn’t stop moving. There would be smoke arising from the left side of the car which frightens me. I just bought the car 2 months ago and couldn’t drive it until I registered it and got my drivers licenses. I understand this is very dangerous especially during rush hour or what not so I want a solution to this as quickly as possible 😬.

 

What have you checked so far?

 

How's the pedal? Works easily, or feels like you're trying to crush a garbage can with your foot? A bad booster will be hard to press, but the car should still stop with more pedal effort. If the pedal feels normal you may have a bad master cylinder or, as you speculated the system needs bleeding. Have you tried bleeding the system yet? How does the fluid look. If it's old it may have too much moisture in it and could be boiling. Try jacking up the car and see if the wheels spin freely, then have someone step on the brakes while you're trying to turn the wheels and see if there's any braking going on.

 

Thank you for replying, When pressing down on the break pedal, it doesn’t feel like it’s extremely hard to press but it feels spongy and break-ineffective. I would slam on the breaks while going 20 on idle and it would break but dangerously slow. The previous owner filled up the break fluid but he may have done it a little funny.

 

Thank you for replying,
nothing yet, what’s first?

 

In that case I'd start with the basics. Follow the bleeding procedure in the manual first. There's no ABS or anything special in an '84 brake system so it should be straightforward. You do have a manual, right?

 

did it always do this? If it's a new problem? Do the brakes get a little better if you pump them?
I wouldn't think the brakes need bleeding out of the blue. You probably need a new master cylinder

 

Do the bleed just to get any possible air out, but if you're putting all you got into a hard pedal there's a problem with the booster. So start with taking air cleaner top off and there is a black canister back left corner it is easily unhooked with car running it should have vacuum on booster side also check that hose from canister to booster make sure no kinks or cuts. Also inspect booster for cracks.

Next with all hooked up pump brakes and hold start car, if booster is working pedal should drop if not you need a booster. Don't freak out a person who just got their license fits under the dash better than us old farts and it's not to tough of a job.
As for the smoke take a look you will probably find it's coming from the exhaust area, 84s were born with valve cover leaks

 

Thank you for replying,
There is no ABS, and I purchased the Haines manual. This is safe to do on my own (DIY) or should I give it to a local professional?

 

Thank you for replying,
I haven’t tried pumping them and this was a problem when first bought the car. It wasn’t as bad as it was now so I’m not sure what the issue is. I’m going to first bleed the breaks, then if that doesn’t work I’ll look into getting a new master cylinder.

 

Thank you for replying,
I appreciate all of your effort in trying to get me to understand this operation. I’m 18 years old and still in high school so I probably shouldn’t have a hard time understanding and doing the process? I’m going to try my best to do what you suggested when I get home.

 

Not sure if it’s any similar to mine(2016 z06)but I had a faulty 103mm katch tb and what the issue was that, it was always opened at around 30%, so everytime I would put it in gear n slowly let the clutch off it would start accelerating on it’s own or if I’m in neutral the car would rev about at 30%. while taking the car to the shop, I had to constantly apply pressure on the brake, or even at the light I would force my foot on the brake
While the car wants to go. I would get warnings saying “brake assist”. And when the car was done after a month of waiting for a new tb, I picked the car up and as soon as I drove out the parking lot, something blew I’m guessing it was the brake booster, and ever since then my brakes been bad, I would have to push my foot on the brake all the way just for it to barely stop. (Plenty of pads left, like new rotors)

 

edit: dang i see u havnt posted since october.



hey kid. thats great that u bought this car and glad u realize u need to sort this out before going anywhere. i have a 14 year old neighbour kid and my own 13yo kid who just picked up and 85 and an 84 respectively.

First, if you get under this car to do any work or inspection…..using a jack and MULTIPLE JACKSTANDS you do it with a friend or or other helper, and you backup your jacks every way you can until you can afford a set of quickjacks or something. Many people slide the tires under the car but they just take ip space and probably wouldnt keep the car off your head with their width anyway. USE multiple jackstands, and leave the jack as a redundancy under the side you are on…..Im a 47 yo dad and love that you have picked up an 84. But u be sure to take zero chances with that car in the air.

Ok….

With the car in the air my friend the first thing to do is find out where the fluid is leaking out. You mentioned a PO added fluid. That means its leaking out. No point doing anything until you discover or rule out a leak. Use you phone and post up some pics of the undercarriage and its brake lines. Follow them from the master to each caliper. Best to get all the wheels off.
If you find a leak, post pics, we will help u.

After You rule out or repair the leak, u need to bleed the brake master cyl. The thing with two white plastic reservoirs. I have bled the master on the car, by pumping the pedal. ive also removed it from the car then used a big oversized phillips screw driver to plunge the masters piston myself until there is no air left.

video of how to “bench” bleed the master. You could also try leaving master on the car.

ignore the fact that the brake master looks a bit different. its the same principle.





once that is done

…..Then you need to bleed at the calipers. Let me stress here. Simply watch chris fixes one man bleeder route and do it that way. Dont skip any steps. ensure two thing always! a) there is always fluid in the master!!! (it will be dropping its level with each pedal pump) and b) the hose in the container needs to be below the fluid level before starting (or it will suck back air)


video:




chris fix video above


Then most likely you will need to pull your calipers off the slide pins and clean them up.

the gotchas here are a) be ultra careful not to rip the rubber boots at the caliper pins

b) support the caliper weight with a piece of wire.


Duringbthis phase, id take the opportunity to push the caliper piston all the way in. I use a cheap VERY LARGE C Clamp. u can google that. Its very possible you have a seized caliper piston. You will be able to tell if it wont push in with the c clamp. if it is, let us know. not a big deal.


Do u have basic tools available? Covered workspace?

Nudging @rbracing