pfergy600

I'm not a mechanic by any means. I had a mechanic install a new Delco-Moraine Brake Booster and Master Cylinder on my 72 Olds Cutlass. It took him for ever to bleed the brakes. To make a long story short, he FORGOT to install the Front Hydraulic Push Rod. There is no Vacuum, so not being a mechanic I am assuming one of the Diaphragm has Failed. My question is do you think that the part is Defective or the Mechanic screwed up and caused damaged to the Booster? The bought the Booster from Summit Racing in April 2014 for $135.. Over a year, so I'm sure I am SOL. Even though I had it just installed last week.

Thanks

pfergy600

Just to clarify, I'm not a mechanic by any means. I had a mechanic install a new Delco-Moraine Brake Booster and Master Cylinder on my 72 Olds Cutlass. It took him forever to bleed the brakes. To make a long story short, he FORGOT to install the Front Hydraulic Push Rod. There was no Vacuum, so not being a mechanic I am assuming one of the Diaphragm had Failed. My question is do you think that the part is Defective or the Mechanic screwed up and caused damaged to the Booster? I bought the Booster from Summit Racing in April 2014 for $135.. I haven't called Summit yet, but I am assuming I am SOL since it has been over a year since I purchased it. Even though it was only installed last week.

Thanks

Allan R

The booster is plug and play, so I'm not sure what you're getting at about the hydraulic push rod. Did he tell you he forgot? Is the brake pedal spongy? Does the car not stop when you step on the brakes?

If it took forever to bleed the brakes, it sounds like he didn't bench bleed the master cylinder before installing it. The MC's sit at an angle in the old cars, unlike horizontal in the new ones and will never bleed out properly when mounted that way. Likely, the MC needs to come off and be bench bled in the horizontal position, reinstalled and the brakes bled again. If that's what did happen? I'd find another mechanic as that's a real dumb mistake that should have been caught right off the bat.

No Vacuum?? Your booster is hooked up to vacuum so that makes no sense.

BTW, you can delete any of the threads you post at your leisure. Just go to the 'edit' box of your post and follow the 'delete' options there.

pfergy600

The car does stop when you hit the brakes but feel very spongy. He did not bench bleed the master cylinder. However, when he pulled off the vacuum valve there was absolutely no suction after and before the car was taken for a test drive. There was suction coming from the hose that I believe leads to the number eight piston. So my mechanic is saying something to the effect there is no vacuum advance once he unplugged that valve from the master cylinder that leads to the intake. Yes he was having A hard time trying to bleed the brakes, and upon further inspection he forgot to remove the pushrod or valve rod from the old booster And put it on the new booster. Excuse me my knowledge is limited as far as which rod that he forgot to remove from the old booster. I called Summit racing and they referred me to the company in Ohio that makes the booster which is called Right Stuff Detailing. I spoke with a representative from Right Stuff Detailing and they were pretty cooperative, told me to ship back the booster and they will inspect it and warrantee it.

70cutty

This doesn't make any sense. New booster comes with everything you need. There is nothing that you need from the old booster.
My suggestion to you is to try a different mechanic. It doesn't sound like this guy knows much about brakes.
If there was a rod missing (not sure what he referring to) the car wouldn't brake at all. Sounds like the brake system is not properly bled.

Allan R

RUN! FIND ANOTHER MECHANIC!! He's incompetent. That MC needs to be bench bled OFF the car. The vacuum tee for the Brake Booster comes from the intake manifold, not the the #8 piston or spark plug. If it was drawing good vacuum through the hose, it's doing what it's supposed to.

Your mechanic is not a mechanic. The new Brake booster comes pre-assembled and the only loose parts he might have had to work with were the clevis and cotter pin. RUN FROM THIS GUY. If there's vacuum from the intake and he unplugged that? He's an idiot.

Right Stuff is very reputable. It's not likely the booster has any issues at all, in fact I'd bet you $$$ that bench bleeding the MC properly and re-bleeding the brakes will solve your problem. Spongy brakes are typical of air still in the brake lines. Take this to a mechanic who knows what he's doing. Heck, you can bench bleed the thing if you want to quite easily. There are tons of DIY vids that show how to both bleed the MC and the brake system. You don't need to be a mechanic to do this - it's really easy. Just time consuming. Save the grief, frustration and $$ by doing it yourself.

NOTE: Caution - brake fluid is corrosive to paint so make sure you don't spill any on that new paint of yours. The MC should have come with plastic plugs that will screw into the ports on the side. Get them back from your old Mechanic and this is a slam dunk.

joe_padavano

If you are not getting vacuum in the hose, that problem is unrelated to the booster. The hose goes to the intake manifold, not the number 8 cylinder (and the back one on the driver's side is number 7, by the way). Verify that the metal line and tube are not plugged and that the plastic check valve is functioning properly. Basically if you pull that hose off the booster with the engine running, the engine will usually stall due to the massive vacuum leak.

The brakes should not be spongy. That is yet another different problem, likely due to air still in the lines. Find a real mechanic, not your current "mechanic".

rustyroger

Surely someone here can point pfergy to a competent mechanic near Tampa. He sure could use one.

Roger.

pfergy600

Joe , I was there when he pulled that hose from the booster and there was suction coming from the intake manifold. He plugged it back into the booster and ran the car for a little while, shutting it off shortly after. But he did say once the car we shut off and sitting in a little while , you should be able to pull that plug on the booster and you should hear a vacuum noise, which there was no noise or suction.

70cutty

Find a new mechanic. Once you shut the car off and let it sit for a while??? Am I missing something here. If the car is not ON, there is nothing creating vacuum so how is it gonna have suction or vacuum. (maybe somebody more knowledgable can explain this).

Take it to a REAL mechanic who can bleed the brakes properly.

pfergy600

Allan, as far as the brake fluid is concerned reference to damaging the new paint job. He said he used DOT-5, I guess it's silicone-based or some kind of synthetic fluid which he said will not damage the paint. We also put new stainless steel brake lines and move the proportioning valve up next to the master cylinder as seen in the more current picture. He thought the headers on the car would be too hot and too close to where the proportioning valve was on the bottom of the engine.

pfergy600

Again thanks for all the responses. I will be looking for a new mechanic. When I mentioned the number eight cylinder I was just trying to describe where that hose was coming from that led to the brake booster. I am by no means a mechanic whatsoever so I was just trying to describe where where that hose was coming from. As I am aware of now that it was coming from the intake manifold on the passenger/firewall side. I saw him disconnect the valve from the booster and he put his thumb on the hose and it had plenty of suction. Hopefully I'm not confusing anybody, but you're talking to somebody who just likes to drive and is in the process of learning more about the mechanical end of it.

70cutty

DOT5 is a lot harder to bleed and get all the air out than DOT3

Allan R

^^^ THIS!! Car ON = Running engine/vacuum source. Car OFF = no vacuum source, period.
That's true, but DOT 5 is well known to absorb (not trap) more air and can result in spongy brake feeling due the the increased compressibility of the fluid. That could be part of your issue with spongy brake feeling. All disc brake cars have some degree of sponginess, the big concern is if it's too spongy and requires too much pedal travel.

From this, I think the whole problem is the DOT 5 and the bleeding. If your car stops fine but the pedal feels too spongy? Change over to DOT 3 mineral base brake fluid. You'll need to completely purge the system if you do that. I looked at the brake lines on my 72 when I replaced them 2 years ago. They weren't corroded in the slightest and they were 41 years old. If you're just driving it and enjoying it? Just do routine DOT 3 brake fluid flushes every 5 years or so and you're golden.

pfergy600

The mechanic, also mentioned there was no vacuum assist. However I have no idea what that means, LOL.

Allan R

Translation: He doesn't know what he's talking about. The brake booster is an 'assist' which relies on vacuum to function properly. Where did he graduate from? Mars or someplace without oxygen? Sounds like he has brain damage.

pfergy600

Anyone know of a Good Mechanic in the Tampa area ???

bccan

It is possible to get a booster without the short front pushrod, been there & done that. Symptom was a spongy, inconsistent pedal. If mechanic was judging thoroughness of bleed by feel of pedal w/ no front pushrod than he may have been fooled by sponginess.


There should be residual vacuum in the booster after engine is shut off. Enough to give you 2-3 brake applications with assist, that is largely the function of the valve as far as I know. It should give you a whoosh when you pull the check valve from the grommet after shutting down the engine. For clarity the check valve is that white, tan or brown disc w/ barb fittings for the hose & booster grommet.


If master cylinder is not bench bled prior to installation it can cause problems bleeding system.


DOT 5 can cause a softer pedal than DOT 3 as mentioned but usually will get a decent to good range of feel. Low/no vac to booster will cause a hard to push pedal due to no boost. Bleeding & booster are mutually exclusive items/problems.

pfergy600

Yes that is what I was trying to describe that whoosh sound when he vehicle was off and he disconnected the Check Valve from the booster after the engine was off. Residual Vacuum is the other word I was looking for. This car was also convert to front disc brakes. So we had vacuum coming from the engine/intake manifold. I think he mentioned something between 18 and 20 not sure if that's the pressure. Said he thinks that the diaphragm inside the booster might be bad. I am not sure if these boosters can ever come defective , but I guess I will find out once I send it away for inspection.

bob p

^^^ YES.

I don't want to fuel a DOT 3/4 vs. DOT-5 debate (there's probably been one here before), but that might end up being unavoidable.

I'll take a different tack, and suggest that your mechanic may not be incompetent, and that several different things could have happened in confluence to cause your spongy feel problem. You'll need to eliminate these things before it's fair to call someone incompetent. There are 4 basic points that need to be considered.

First, some people just don't know that DOT-5 requires special techniques when bleeding that aren't necessary with DOT-3 or DOT-4. DOT-5 shouldn't be bled using the techniques that you learned to use on DOT-3 or DOT-4. If you go pressurizing a line that has DOT-5 and air in it, then all that you do is force air into the fluid, and that WILL cause spongy brakes that will remain forever. It will take hours for the air to bubble out, so you have to wait before you try to bleed again. Then, you need to bleed with VOLUME, not with PRESSURE. If you don't have specialized gear for HVLP bleeding then bleeding DOT-5 is a very tedious experience and you may never succeed.

DOT-5 brake fluid has pros and cons associated with it. When it works it's great, but when it doesn't work it's a royal pain in the ****. Air entrainment is one of the cons to working with DOT-5. You have to let the fluid sit on a table for an hour after you move the bottle, to allow any entrained air to bubble out, before you use it. Then you have to be very careful about not pressurizing the line while there's any residual air. Harley products use DOT-5 and their brake bleeding instructions specifically caution about air entrainment.

Second, bench bleeding is or is not necessary depending on the equipment you use. Bench bleeding is absolutely necessary if you're going to use any of the easy shadetree-type bleeding methods, like the one man pump the pedal into a jar method, the two person pump and wrench method, or the vacuum bleeder / Mityvac method. To have success with these systems you really need to bench bleed the master cylinder before bleeding the lines

OTOH if you're using professional brake bleeding equipment, like a Branick G300, then bench bleeding is an unnecessary waste of time. You just fill the master, pressurize the system and blow the bubbles out downstream. The flow rate is high enough, the volume is high enough, and the flow is consistent enough that any air entrained in the master cylinder is blown out with the quart of fluid that you use to purge each corner.

The real problem comes along when people are too cheap to buy a G300 but they decide to build their own DIY pressure bleeding system using a garden sprayer. Those systems have a pressurized air / brake-fluid interface, and they force air to be entrained into the brake fluid. It's impossible to avoid air entrainment with these systems, so I'd avoid them.

Third, if your mechanic tells you that he didn't bench bleed the master, that does not mean that he's incompetent. It may just mean that he used a pressure bleeding system, which would make bench bleeding unnecessary. A potential problem occurs, though, if you try to power bleed DOT-5 using a garden sprayer type of setup instead of a G300. Anyone who uses the garden sprayer setup with DOT-5 is guaranteed to have problems. To do DOT-5 properly, you shouldn't use anything other than a G300, which makes bleeding quite expensive as the G300 wastes a tremendous amount of fluid in order to make brake work fast and easy on the professional mechanic, whose time is money.

Fourth, if you try to use a MityVac, the pump and wrench, the or pump into a jar to method bleed DOT-5, chances are that you'll never get a high enough and a consistent enough flow to fully evacuate the air without entraining some air into the fluid. DOT-5 acts like a capacitor for air (yeah, I made up that term), which can make DOT-5 bleeding a tremendously drawn-out procedure. IMO you really need a G300 to do DOT-5, as it can be configured as a HVLP pump that prevents air contacting the brake fluid, and has a high enough flow rate at low pressure to flush the line while preventing air entrainment. (The amount of air that gets suspended in DOT-5 is directly proportional to pressure.)



When I was thinking about trying DOT-5 I conducted a poll among the local car guys. Several locals have tried using DOT-5. One of them had 3 cars on the cover of Hot Rod. Not one of them was ever happy with the braking feel of their cars, all of them said that the brakes felt spongy, and they were unhappy because they wanted the sensation of having brakes that could throw you through the windshield. Several different people tried bleeding each other's cars and none of them could ever make DOT-5 give them that "through the windshield" feel. Every one of the guys that I know who has used DOT-5 ended up flushing out the system with denatured alcohol and converting to DOT-3 or DOT-4. As soon as they made the switch they got the "in your face" brakes they were looking for.

I thought about this long and hard several years ago, and did a lot of research about whether or not to go with DOT-5 because I was attracted to the idea of avoiding repeated brake bleeding on my car and bike collection. I don't know anyone who has ever gotten DOT-5 to work the way they wanted it to. Every person I've personally spoken to who has tried DOT-5 has switched away from it. I only have one DOT-5 vehicle, a Harley, and I've never liked it's brakes. They feel spongy. On my sportbikes with DOT-4 the brakes are hard and firm and easy to control. I can do a stoppie (reverse wheelie). I decided not to go with DOT-5 on my cars. I went with DOT-4 instead. Someday I'll switch over that Harley.

I hate brakework. I hate drums the most. But I've got a dozen vehicles that I need to keep serviced, and the work takes so much time that I couldn't stand doing it all by myself. I spent the big bucks to buy a G300. Now I just buy DOT-4 in gallon jugs, break out the G300 once a year, and spend a weekend flushing all of my vehicles. They all have great brakes.

In a roundabout way, I guess I've said that I disagree that your mechanic has to be incompetent because he didn't bench bleed your MC. Bench bleeding is not necessary if you have professional flushing equipment. It's only required when you don't.

It's entirely possible that your mechanical components are OK and that your brakes feel spongy because you have air entrained somewhere in your DOT-5 system. My two-cents worth of advice would be that you should eliminate all of the other possibilities first (like defective vacuum booster, vacuum leak, poor vacuum seal at the MC, bad pushrod calibration, etc.) before labelling your guy as incompetent and before deciding to get rid of DOT-5.

If you like the idea of DOT-5, then pay the money to go to a high end professional rod and custom shop that has a G300 that's dedicated solely to DOT-5 use. With an HVLP bleed they will be able to fix your sponginess problem if your sponginess is due to air, but it will be expensive because they will end up wasting at least a gallon of DOT-5 to fully purge the system.

Another option would be to just punt on the DOT-5 and go back to DOT-3 or DOT-4, which is easier for the average guy to get the air out of.

FWIW, I just use DOT-4 and flush every year. Other people probably do things differently.

Good luck!

Fun71

As bccan posted, there is a one-way check valve so the booster doesn't lose vacuum (for a while, anyway) when the engine is turned off.

oldsmike1972

Nice post by bob p!

I too, do a yearly brake fluid purge, all done with the Mityvac. The natural color of the fluid is CLEAR. It isn't the color of coffee which so many are... I should invest in the G300 too as I have at least 6 vehicles to maintain. During the Christmas break, I do the annual fluid changes on everything. Brakes, Transmission and Rear Diff. Brakes get bled at each corner till runs super clear. Transmissions get new filters, synthetic oil and magnets cleaned. Rear diffs get the magnets cleaned and new synthetic.

I should get that lift in the shop too!!!

Regards,
Mike