[MMueller]

So I'm completely green in terms of working on cars and my '74 Nova is my first time really working on anything.

I had a friend do the brake lines for me and now the brake pedal intermittently seems to lose "resistance", aka feels limp. This happens probably once out of five times stepping on it if I had to take a guess. The brakes still engage but not until the pedal is very low to the ground already.

Could this be caused by an air bubble? Trying to figure out what to even start looking for to rectify this.

PS: My friend is out of town for a few weeks so I can't just take it back to him right now and would prefer not to wait.

Thank you guys for any help in advance :yes:

 

[ProjectX]

If he didn't put a new master cylinder in and just changed the lines then there is either a leak on one of the connection points or it needs to be re-bled and possibly has air in the lines still.

 

[MMueller]

If he didn't put a new master cylinder in and just changed the lines then there is either a leak on one of the connection points or it needs to be re-bled and possibly has air in the lines still.

No new master cylinder, no. I'll educate myself on how to do this and get on it, figured this may be the reason.

Thank you for your input.

 

[RifRaf]

I just posted this information in another thread, but it may be helpful to you too.

I think you still have some air somewhere in your brake lines.
If you are using the "pump the brakes and hold" method of bleeding your brakes, there are a couple of things to consider.

Never let your master cylinder run out of brake fluid during the bleeding process. If you do, you'll have to start all over since air has gotten into the braking system.

You want to slowly pump your brakes to build pressure while bleeding. I was taught that if you are quickly pumping your brakes during the bleeding process, you may introduce some air bubbles into the brake fluid within your master cylinder.

Always start bleeding the brakes at the farthest location away from the master cylinder and proceed to the next farthest.
Bleeding Order: Pass Rear - Driver Rear - Pass Front - Driver Front

As you are holding pressure on the brake pedal and then loosen the bleeder valve to release the air and/or brake fluid from the calipers, keep the brake pedal on the floor until you have re-tightened the bleeder valve on your caliper (or cylinder for drum brakes). If you let the brake pedal raise before you have tightened the bleeder valve (or you just leave the bleeder valve open), you could be sucking air back into the caliper thru the bleeder fitting threads.

 

[MMueller]

I just posted this information in another thread, but it may be helpful to you too.

I think you still have some air somewhere in your brake lines.
If you are using the "pump the brakes and hold" method of bleeding your brakes, there are a couple of things to consider.

Never let your master cylinder run out of brake fluid during the bleeding process. If you do, you'll have to start all over since air has gotten into the braking system.

You want to slowly pump your brakes to build pressure while bleeding. I was taught that if you are quickly pumping your brakes during the bleeding process, you may introduce some air bubbles into the brake fluid within your master cylinder.

Always start bleeding the brakes at the farthest location away from the master cylinder and proceed to the next farthest.
Bleeding Order: Pass Rear - Driver Rear - Pass Front - Driver Front

As you are holding pressure on the brake pedal and then loosen the bleeder valve to release the air and/or brake fluid from the calipers, keep the brake pedal on the floor until you have re-tightened the bleeder valve on your caliper (or cylinder for drum brakes). If you let the brake pedal raise before you have tightened the bleeder valve (or you just leave the bleeder valve open), you could be sucking air back into the caliper thru the bleeder fitting threads.

Thank you very much, very useful info since I'm learning all kinds of basics still. Where exactly are the bleeder valves located if I can ask? Just on top of the caliper and/or cylinder?

 

[RifRaf]

Yes... The bleeder valve is located at the top portion of your caliper (disc brakes) or cylinder (drum brakes)... normally positioned just above where the brake line is attached.

The attached youtube video may also be helpful in identifying the brake bleeder valves and the correct procedures used to correctly bleed your brakes.