Brake Issue

[zoulas]

Hello again, 1965 GMC Panel 305E

The truck unfortunately sat for a while (my fault.) When to start it today and when I stepped on the brake, the petal sank to the floor with zero pressure. Pumped it 20x, still nothing. Checked master cylinder, empty. Checked for leaks around wheeles, did not see any. Filled the master cylinder with new brake fluid. Pumped the petal 10-15x. I got some resistance but not quite normal. Waited few minutes, the petal sank to the floor again with no resistance.

If I repeat the process I get some resistance but it goes away after few seconds. When I pump it and the resistance builds, if I hold the petal , it keeps the resistance. It's only when I release the petal that the resistance goes away.

I checked for leaks again around the wheeles and did not see any. I checked the master cylinder again and it was full, no fluid loss.

Any ideas?

Thanks in advance.

[jagarra]

You have air in the system, it will have to be bled to remove air. Get a friend to pump the brakes up and start with the wheel furthest from Master, rt rear. Do them in order at least twice.
Since you checked wheel cylinders for leakage, check master to see if it's not leaking, I've had extremely slow weeping on them before.

[zoulas]

Thanks, is there any web inks you can point me to? Possibly a video? Thank you

[AZKen]

In google, type in: how to bleed brakes

You may also have a worn out master cylinder.

[zoulas]

If I wanted to get another master cylinder, is there a part number? Is it still made?

[Funky61]

Which style do you have?

https://www.rockauto.com/en/catalog/gmc,1965,2500+series,5.0l+305cid+v6,1440778,brake+&+wheel+hub,master+cylinder,1836

[jagarra]

My local NAPA store listed the master (dual with clutch and brake) as well as rebuild kits.

[AZKen]

He should have the mechanical clutch and use a single reservoir master.
CLICK (https://www.rockauto.com/en/catalog/gmc,1965,1000+series,5.0l+305cid+v6,1419397,brake+&+wheel+hub,master+cylinder,1836)

[zoulas]

Would something like this work to bleed the brakes:


ARES 70923-1-Liter Vacuum Brake Fluid Bleeder - Hanging Hook and Locking Trigger Allows for Hands Free Operation https://www.amazon.com/dp/B07CP1YLDF/ref=cm_sw_r_other_apa_i_89L7EbSKG5HGP

[FetchMeAPepsi]

You really don't need a gadget to bleed the brakes. Just open the valve and have a buddy mash the pedal repeatedly. It only takes a few times until there's no air coming out, then you're good to go. Catch the fluid in a can as it squirts out and re-add it to the system so you don't waste any. Or let it blow out on the ground if you have a lot and don't want grass there for the rest of the season :lol:

[AZKen]

If you are going to use one like that, THIS (https://www.amazon.com/8milelake-Pneumatic-Brake-Bleeder-Cylinder/dp/B013WKCKW0/ref=sr_1_11?dchild=1&keywords=vacuum+bleeder&qid=1592719896&s=automotive&sr=1-11) is the one you want. I use this one. It is a one man deal. Keeps the master full, any master, while you bleed each wheel. No mess, no jars, no empty water bottles, no pedal pushing helper, no checking the master level.................... But you need an air compressor.

[zoulas]

Can someone give me a hint where the bleeder valve is in these pictures?

[AZKen]

Above where hose or hard line goes into wheel. Covered up by leaves. Each wheel has one.

[Jim A]

zoulas:
I think it is great that you are trying to get your truck back on the road.
It doesn't look like you have much experience working on vehicles and I hope you will enjoy learning how to do so.
I would like to suggest finding a friend or relative who is knowledgeable to guide you.
Failing that, please find a professional mechanic to check your work, especially in regard to brakes.

[FetchMeAPepsi]

Jim A is right. The safest thing to do with brakes is have someone qualified look at it. If you're broke like I was when I was arm deep in Cecilia, you can do a recycling run on the brakes. Again, using the helper.

First, what are you doing by bleeding the brakes?
You're basically making sure you have no air bubbles in the system so you can smash the brakes and it won't hit a soft spot, keeping pressure on the brakes so they stop your butt before you become road pizza (or in the case of our tough 60's model trucks, kill someone in a coke can car!)

To do this, you'd fill your brake reservoir to almost full to allow for some sloshing as the pedal goes up and down. It won't really slosh, but it does move up and down a bit.

Then have a random foot from the neighborhood sit in the seat and be ready to mash the brakes while they play on their phone. This will take a while. Make sure they're entertained. Tell them when you yell "Mash" they mash THEN HOLD IT DOWN. Don't forget that part. If they pull up it may pull air back into the line. That's a no-no.
When you yell "Let UP!" they can let up.

You, meanwhile get your dirty work shirt on and crawl under there. Open the bleeder valve and put a hose on it or just let it drip into a clean container. Yell "Mash" and make sure they hold it. As the fluid runs out into your can, it'll slow down. As it slows close the valve and yell "Let up!".

Repeat this four times then take your can of saved fluid and pour it back in the reservoir if it's clean.

Repeat the refill four times. That's 12 times of yelling "Mash!" and "Let Up!" for each wheel.

This should be 99.9% sure have all the air out of that particular line. That's a lot of fluid to run through a brake line. If there's air in there it's tiny microbubbles and shouldn't be a problem. They'll sort themselves out as you drive, and empty themselves in the reservoir.

This is what I'd do if I was broke and needed to get her running with 100% certainty (on my part, your certainty may vary).

Again, it's worth noting that I'm not a mechanic, just a dude standing in front of another dude giving advice that is worth exactly what you paid for it. You might have a hole in the line somewhere, suck air in, and die in a fiery crash full of gas and fireworks that look beautiful on the evening news.





http://www.humoar.com/wp-content/uploads/uegifs/unicycle-explosion.gif (https://windypix.com/?pm=29W9)

[zoulas]

Hello, and thank you for your comments. I categorically disagree with your statements. Professional mechanics do not know how to repair and troubleshoot old vehicles. If they cannot connect a scanner to the built in computer , they are lost. I did take the truck to the local reputable mechanic several years ago. What did they do? They told me I needed new brakes. I approved the cost. They changed the brakes and never serviced the brake cylinder. Six months later all brake cylinders were leaking.

Is this the level of service you are recommending?

If you want something done right, you have to do it yourself period. This is my plan. Anyone interested in helping, feel free to do so.

[James]

Hello, and thank you for your comments. I categorically disagree with your statements. Professional mechanics do not know how to repair and troubleshoot old vehicles. If they cannot connect a scanner to the built in computer , they are lost. I did take the truck to the local reputable mechanic several years ago. What did they do? They told me I needed new brakes. I approved the cost. They changed the brakes and never serviced the brake cylinder. Six months later all brake cylinders were leaking.

Is this the level of service you are recommending?

If you want something done right, you have to do it yourself period. This is my plan. Anyone interested in helping, feel free to do so.

I agree with you. I've seen to many so call auto mechanic claiming they know what they are doing only costing me more money and time. Back then I was young and didn't have the place to do the work. Over time I got my own place and now there is almost nothing I can't do on my truck.

I also use a bleeder tool. When you don't have any help and the job needed to get done right the first time. It don't cost that much and it saved me a lot of time.

[AZKen]

Zoulas, Not sure whom your post is directed at. You are now a turn off new guy.

"I categorically disagree with your statements. Professional mechanics do not know how to repair and troubleshoot old vehicles."

"Is this the level of service you are recommending?" ARE YOU KIDDING ME? WHAT KIND OF STUPID QUESTION IS THAT?

You have asked such basic questions that we all believe you do not know what you are doing. You don't search the internet. You are wrong about mechanics not knowing about old truck brakes and how to fix them. Just because you got scalped by a bad shop does not say anything about mechanics, it reinforces that you don't know what you are doing.

Disrespecting (disagreeing categorically) someone taking the time to help with some really good warnings about brakes being a safety issues, and advising one possible option is getting hands on experienced help, or professional help, for you and your families safety, is BS.

Many on here ARE mechanics.

Many mechanics and experienced builders have been holding your hand and answering every question. Including me. Finding parts and pictures for you and posting them. Guess how we found them. We searched Google for you. While you thought up the next question.

We can't train you on every single basic issue and be a virtual 24/7 answering service for arm chair Truck owners with a thankless attitude.
I gave up on you 2 days ago but you are over the line. Few will be interested in helping you now.

You want to do it yourself but you haven't done anything yourself. You can't even find the bleeder valve under the leaves. Sell your truck and take up numbers painting.

[FetchMeAPepsi]

Hello, and thank you for your comments. I categorically disagree with your statements. Professional mechanics do not know how to repair and troubleshoot old vehicles. If they cannot connect a scanner to the built in computer , they are lost. I did take the truck to the local reputable mechanic several years ago. What did they do? They told me I needed new brakes. I approved the cost. They changed the brakes and never serviced the brake cylinder. Six months later all brake cylinders were leaking.

Is this the level of service you are recommending?

If you want something done right, you have to do it yourself period. This is my plan. Anyone interested in helping, feel free to do so.

Servicing the brake cylinder isn't usually included in new brakes. They just swap the brakes and make sure they work. And it's usually done by a Brake Tech, which is car talk for "pimply teenager that needed a job". They are almost always not a mechanic.


Look on Yelp or the Neighborhood app and you'll find a reputable mechanic. Then call and ask him flat out, "do you know anything about older cars? I just want you to look at what I did and see if it looks good. I won't hold you responsible and I'll pay you a 1 hr shop fee for your trouble, even if it takes 10 minutes. "

If you talk to him like an old friend you'll probably get better results. Tell him you're new and this is what you did, and does that sound like a good way to do things. Or have him bleed the brakes and sit there and watch him. Ask questions. Then (most importantly) thank him for putting up with your newbie questions and teaching you a little bit more about the vehicle you love.

:thumbsup:

You can do all this stuff yourself but you've got to know WHY you're doing what youre doing or you'll make mistakes. Just like I did when I started out. Lots of them. costly ones. So costly...

[zoulas]

AZKEN, if you feel the question is too basic for you, you can pass and let someone else take a shot. I did not insult you personally, yet you chose to insult me personally. You said: "we can't train you" . I never asked for training. I am just a guy with a GMC truck (just like you) with a question that I asked on a GMC forum. Your participation is completely voluntary.

[James]

You can do all this stuff yourself but you've got to know WHY you're doing what youre doing or you'll make mistakes. Just like I did when I started out. Lots of them. costly ones. So costly...

Oh so true. Been there done that.