[Tennesseestorm]

I usually only drive my 73' on my day off- which was today. When I got in it to start it this morning- it made an odd noise under the hood- like a "whining" noise. A little noise like my tranny makes all the time when shifting from 1-2, but it was louder. It stopped after about 10 seconds. It had never did this before, but I did change the fluid and filter last Wednesday. My main problem for now is that when I went to take it out of park, the pedal was very soft and went to the floor and braking power was very minimal. With a quick initial inspection, I did not see any fluid leaks from any of the wheels or booster/master cylinder. It was bad weather today, so not much time to inspect it.

Does anyone have any ideas just from what I have posted? Someone said it could be a busted wheel cylinder. The car is 33 years old and the entire system is original, so I guess it is time for something to go bad. Dad said it may be the master cylinder failing. The brake warning light was not illuminated during this, but the light does work, because it comes on when I turn the ignition and when I set the emergency brakes.

Any info appreciated.

[Tennesseestorm]

I usually only drive my 73' on my day off- which was today. When I got in it to start it this morning- it made an odd noise under the hood- like a "whining" noise. A little noise like my tranny makes all the time when shifting from 1-2, but it was louder. It stopped after about 10 seconds. It had never did this before, but I did change the fluid and filter last Wednesday. My main problem for now is that when I went to take it out of park, the pedal was very soft and went to the floor and braking power was very minimal. With a quick initial inspection, I did not see any fluid leaks from any of the wheels or booster/master cylinder. It was bad weather today, so not much time to inspect it.

Does anyone have any ideas just from what I have posted? Someone said it could be a busted wheel cylinder. The car is 33 years old and the entire system is original, so I guess it is time for something to go bad. Dad said it may be the master cylinder failing. The brake warning light was not illuminated during this, but the light does work, because it comes on when I turn the ignition and when I set the emergency brakes.

Any info appreciated.

[RAJNWDY]

the brake light in the dash would light if you had an imbalance in the system. the light connects to the Proportioning valve. Since you pressed on the brakes and did not realize an imbalanced system such as what would happen if a wheel cylinder failing might cause, then I too would look at the master cylinder. If you were able to pump the brakes up and then they would hold pressure then it's possible that your master cylinder is bleeding down when not being run. If pressure doesn't come up then I would replace it first but pull the wheels and do an inspection on everything. I had a car do about the same thing and it was the master cylinder that was the fault. The whinning noise in the trans when starting is usually the pump cavitating in the trans. Usually from a dirty filter but you say you changed it so I would look at my fluid level and make sure I have enough fluid in the trans now that you have run the car for a while.

[Tennesseestorm]

Thanks for the replies. I dodged the rain squalls today and checked it. The rear reservior is out of fluid. ALL of the wheel cylinders are fine- no leakage. There appears to be a break in one of the lines as it does down toward the back of the car near the front floor.

If something happens it is the booster and it needs replaced- how difficult to replace? Don't you have to go under the instrument panel to remove the bolts?

Thanks again!

[Junqueboi]

Your car appears to be well-maintained... I'd be surprised if it was a brake line busted... if you hadn't already, pull both rear drums off to check the rear cylinders...sometimes you won't see any leakage when you just look underneath the car...

The booster is not fun to remove, but it's not too major of a job. I do believe you have to remove four nuts on the dashboard side of the firewall. These seldom go bad unless the master cylinder rear seal blew out & let fluid enter the booster...

The whine is the trans pump as the previous poster noted. Several of my THM400-equipped cars will whine upon initial start-up, especially when the ambient temperature is cold. I used to have a white '73 D88 Convertible that whined every time I cranked it. I put probably 50K on the car like that & never had any transmission issues out of it...

Just don't run the car hard until it's completely warmed up. You probably knew that anyway though.

[6t7gto]

junquboi,
i have replaced all 3 of my boosters on my 3 A bodies.
all 3 boosters had the nuts on the engine side of the firewall.
on full sized bodies are the nuts under the dash?
david

[63 Pontiac]

I had a similar problem in my '74 GP, it was the proportioning valve. Replaced it and brakes were fine.

[6t7gto]

junqueboi,
i found the info.
nuts are under the dash.
david

[Tennesseestorm]

Thanks. Forgive my ignorance, but where is the proportioning valve and how do I replace it?

You are right Junqueboi- it was/is a well maintained car. I just happened to see a lot of fluid under the car directly under the firewall, where the brake lines run down. It rained again ALL day today. I did not get off of work until 6:30 and it rained all evening. Currently no garage for it, so....

Another thing I recall, is when I press the brakes, there is a "woosh" sound from the brake pedal area. Like I said, I still have brakes, but they are very weak and the pedal goes almost to the floor and like I found out last evening, the rear reservior was empty. I guess I will see about that valve and pull the rear wheels and check the wheel cylinders.
I just hope it is not the booster. Everything appears to be original- or at least as old as the 1980s, so nothing would suprise me- especially considering the luck I have with cars....

The transmission "whine" also goes on when I drive- but only from 1st to 2nd gear. When it shifts to 2nd, it stops. I have been told by others here that it is something called the front "planatary or planetary"? Said was not really a big deal, but would eventually need rebuilding. I have no idea. I do know when I changed the fluid and filter last week there was a metal clip just laying in the bottom of the pan. I had no idea where it went. Also- was suprised there was no magnet in the pan. Fluid had no dirty or metal in it, but the fluid was obviously old. I checked it and it was full of fluid. I put 4 1/2 quarts back in it. I used Dextron/Mercon. Could not find any plain "Dextron". I am assuming the Dextron/Mercon was OK. Like you said - warming it up is good. I always let the car run until the "choke" releases. When it idles down to normal RPMs after tapping the accelerator, I take off.

[6t7gto]

shaffer,
when my car made the "whoosh" sound, it was a bad booster.
caused by the M/C leaking out the rear and into the booster.
david

[Junqueboi]

I agree with David..

If a new booster's expensive, I'd maybe hit a junkyard for one.

[Tennesseestorm]

I bets that the problem then, since the rear reservior is empty. Drats!

In my book- that was the worst case scenerio....

[Tennesseestorm]

Yeah- a new booster is $109. There are three early 70s Pontiac (71 Grand Safari wagon, 73 Bonneville 4dr sedan and a 71 Catalina 4dr hardtop) that have been setting for MANY years about a mile from here. I am guessing that since they have set so long, that the boosters are probably destroyed. ??


<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Junqueboi:
I agree with David..

If a new booster's expensive, I'd maybe hit a junkyard for one. </div></BLOCKQUOTE>

[Tennesseestorm]

STUPID BRAKES!!!!

Finally got a brake booster and after 3 hours of work, (I have never done anything like this before) I finally got it on- broken back and all. The biggest problem I had was probably the most simple to some, but I had a time getting the plunger rod off of the brake pedal pin.

The wonderful news is that the new booster is bad. It is whistling like crazy when I depress the brakes. We have bled everything. What is also strange is that no fluid will come out of the front wheel lines. The brakes are working fine is another thing that is puzzling. At first, the brakes were going down, but not coming back up. After we bled them more, it started to come up properly. We called the auto parts shop and they said a new one would be in on Thursday morning. Now I get it look forward to removing it again! Just my luck.

Another thing- the replacement booster looks much larger than the original. In fact, it seems to be making the wires that run by it put too much pressure where they come out of the harness. Possibly they sold me the wrong one? Everything bolted up OK though.

[CHIEF8U]

Shaffer, Your last post said you have no fluid pressure to the front brakes... Your proportiioning valve is in the safty front brake lock out position. You need to push the button on the end of the valve to reset the safty. Before you can push the button you need to release all the presure from the system. The best way to bleed your brakes is by gravity. First take the top off the master cyl, then open all the wheel bleeders,then push the button. After you push the button you should get fluid running out all 4 bleeders,then close them all. To bleed the system, with the cap off the master cyl and the reservoirs full, open one bleeder at a time untill the fluid runs clear then move on to another one and do the same thing.
Getting back to your first post. If you had no fluid in the rear resviour, evedence of fluid running down the booster and a bad booster I would suspect the plunger shaft rear seal in your master cyl is leaking.

[Tennesseestorm]

Thanks. Before I read this- I had to take the car to a local repair shop where a mechanic that my dad knows well said that the replacement booster was also bad. So, I got another and installed it last night (Friday night) and plan on bleeding them tomorrow (Sunday). I did not have time today. We did finally get fluid going through the front brake lines. It was where the original brake lines are so old, that the bleeders were stopped up or something.

One thing that is very puzzling now is that the new booster I installed last night seems to have much smaller bolts, as I had a hard time getting some of the nuts started on them. I had to tighten the lower bolts as tight as I could, in order to even get the upper bolts to get a grip on the threads. I was not about to remove the booster again to see if they were indeed shorter, but I guess that it all it could be. I am guessing that they installed smaller bolts on this particular booster?

This was one of the exact reasons why I was hoping and praying that it was not my booster that was bad, because I had a feeling it was going to be a headache. I was so agitated with it last night, I was ready to give the car away. I have not even been able to drive the car for 3 weeks (aside from driving it to the shop the other day with no power brakes - which was interesting).

Hopefully after I bleed them tomorrow, it will be OK. If not, I am tired of fooling with it and I will sell the car before I remove the booster again. I just do not like working on cars on spots I cannot easily get to. I have no idea why they did not do these like they did on the older Pontiacs (or so I have heard), where you can simply unbolt them from the outside, as the firewall holes are threaded and the bolts go in from the outside- which makes more sense to me.

Thanks again.

BTW- Here is a photo of the bolts after I installed it. See how the bolts coming though seem too short? The booster is tight, I know for sure, but it just seems like something about it is not right. Seems like the bolts on the booster should be the same length as the originals.

[Tennesseestorm]

Another

[Tennesseestorm]

Also noticed I forgot to update. That first booster I replaced was not only too big, it was defective. I had to end up getting a "bendix" booster for a 72' model, because it was not listed for the 73s. I then put that on and that was when I had no "power brakes", then took to the shop. He said it was bad too. So, that took me to the above posts.

It has really been a headache.

Here is a photo of my original booster after it was removed:

[Tennesseestorm]

Here was the first booster they sold me that was too large and defective- was whistling when I pressed the brakes:

[Tennesseestorm]

Here was the 2nd replacement booster- this booster was not listed as available for the 73' Grand Ville, only the 72. This one was also defective- no power assist.

The latest one I installed, looks just like the above booster, but as mentioned- the bolts seemed much too short. Much shorter than it was on the others.