Vac Brakes Intermittent!! Please Help!

[RickC]

The car is an '87 GN bone stock and my Wife and I are the original owners. Its her (and the kids) daily driver so this is a real safety issue for us.

I recently did the vacuum brake conversion because I was having so much trouble getting another powermaster. Had almost as much trouble trying to get a new hydro-boost as well so went with vac. Bought a new booster and master cylinder from Autozone for an '84 Buick regal. Did the pedal mod myself and it all fit nicely and seemed to work very well. Ran the vac line to a tee off the PCV valve as mentioned several times here in the forum. Overall the brakes work well although a little touchy compared to the powermaster.

Yesterday she was backing out of a parking lot and stepped on the brakes and the pedal was rock hard. Could barely stop from rolling into another parked car. The only other issue she remembers is that the car was idling rough and almost stalled. Then, she tested the brakes several times and they seemed to have come back. She proceeded out of the lot down a small incline and tried to stop just before pulling out into traffic, pedal hard again. She had to "STAND" on the pedal to keep from coasting into on-coming traffic. The kids were with her and she is now freaking out about the car.

Of course EVERY time I drive it its fine.

Any Ideas? Bad vacuum check valve? Wrong booster?

Please advise....

Rick

 

[TurboBuRick]

Not good to t into the pcv circuit. That could very well be the problem.

Get a vacuum block with a separate port.

 

[captndave737]

I had the same thing happen 99 % of the time they were fine but occasionally nothing, and I mean NOTHING. I had T and changed to a vacuum block. No change. I changed the check valve, No change. I changed the booster and master cylinder, no change.

I went to a hydraboost which worked flawlessly for 3 years but i didn't like the wine so I went back to a Powermaster, Rebuilt from Kirbans 3 months ago. Now I'm stuck 800 miles from home with no brakes!!!!! Going back to hydraboost ASAP.

 

[T-CHRGD]

Not good to t into the pcv circuit. That could very well be the problem.

Get a vacuum block with a separate port.

X2

I've had vac. Brakes for 20 yrs. No problems. Sounds like loss of vacuum. Swap the vacuum block And check All other hoses for leaks. Good luck

 

[RickC]

Thank you all.

Will change all vacuum lines and order new vac block tonight.

 

[Nick Micale]

I have done a hundred of these vacuum conversions where a tee was used at the PCV line, and never have had a problem. [Unless a line comes loose!]

You need to check further, as you may have a vac leak in a line or the booster diaphram itself.

If the car is idling rough, a definite vac leak somewhere?

Hopefully you used a vac brake hose, and not just a some regular rubber hose?

 

[bmackinnon]

Not good to t into the pcv circuit.

BS.... sorry! :redface:

I have done a hundred of these vacuum conversions where a tee was used at the PCV line, and never have had a problem. [Unless a line comes loose!]

You need to check further, as you may have a vac leak in a line or the booster diaphram itself.

If the car is idling rough, a definite vac leak somewhere?

Hopefully you used a vac brake hose, and not just a some regular rubber hose?

+1.... Nick has done hundreds of these vac conversions, and himself advised me about the vac line routing.... My car has NEVER had any kind of problem with the vac brakes.... even after immediate full boost to panic brake transition... obviously you have a vacuum issue, not a vacuum brake issue.... make sure you are using the proper AC Delco PCV valve and it's in good shape... and check the check valve at the booster...

 

[POWERBRAKEBOB]

NEW Hydroboosts

We have new Hydroboosts.They work great, and will outlive any other brake system and even the car! Power Brake Service is THE O.E. distributor for the new units. They come ready to bolt on. Aluminum masters are available, and so are alum p/s reservoirs. As far as the whine in the pump, separating the returns back into the reservoir willl cure that. The alum reservoir has the two returns tapped in, and replaces the cheap factory plastic one.

 

[TurboBuRick]

BS.... sorry! :redface:

No problem, to each is own. Plenty shade tree mechanics are doing it. It just makes more sense to designate a circuit. Less to go wrong. :biggrin:

 

[charlief1]

We have new Hydroboosts.They work great, and will outlive any other brake system and even the car! Power Brake Service is THE O.E. distributor for the new units. They come ready to bolt on. Aluminum masters are available, and so are alum p/s reservoirs. As far as the whine in the pump, separating the returns back into the reservoir willl cure that. The alum reservoir has the two returns tapped in, and replaces the cheap factory plastic one.

Wow Bob, sounds like an advertisement to me. Feel like becoming a vendor or NEVER post stuff like this again?:biggrin:

 

[POWERBRAKEBOB]

Hydroboosts vs vacuum

O.K. BUT, the lead of the thread is that he could NOT find new Hydroboosts. NOW he has brake problems with the vacuum booster. Buick NEVER installed a vacuum booster on a turbocharged car. It didn't work then, why would it work now with used parts? How CAN the vacuum booster, with the low vacuum on these cars, possibly work right? They work O.K. in mild street driving, but not for high performance use. I have rebuilt thousands of those vacuum boosters, and know how to modify them for increased power. I have done those vacuum brake conversions, and the customers were never happy with them. We even added electric vacuum pumps. Still weak.
I was the first to install 7/8" wheel cylinders in those cars in 1987, because the dealers would send me S-10's to add power brakes on non-power S-10's. I discovered that the wheel cyls had to be changed to the smaller one with the addition of the booster. The Regal/G.N. has the same brakes as an S-10, but weighs 50% more. The vacuum booster used for these conversions is also the same as an S-10. So, now, with the S-10 booster, S-10 pads, calipers and rear brakes, how can this combo stop a car that is 50% heavier, and much, much faster?

 

[Nick Micale]

Again with the hydroboost BS...

O.K. BUT, the lead of the thread is that he could NOT find new Hydroboosts. NOW he has brake problems with the vacuum booster. Buick NEVER installed a vacuum booster on a turbocharged car. It didn't work then, why would it work now with used parts? How CAN the vacuum booster, with the low vacuum on these cars, possibly work right? They work O.K. in mild street driving, but not for high performance use. I have rebuilt thousands of those vacuum boosters, and know how to modify them for increased power. I have done those vacuum brake conversions, and the customers were never happy with them. We even added electric vacuum pumps. Still weak. ......

Let's not get carried away here with your hype that Hydroboost is the "Ultimate" way to go.

GM and other makers have, and still do use, vacuum boosters on their cars. Of course you completely ignore the 1989 TTA with a Buick turbo engine and a vac booster? Never heard those guys complain?

Do you even know WHY GM use the Powermaster on the 1986-7 turbo Regals and some Regal station wagons. Maybe do a little research and find some of the GM engineers I discussed this with years ago.

So cut the BS, the vac system is a proven, reliable method, and if you cannot get them to work properly, you are doing something wrong.

There are many hundreds of turbo Buick street cars and race cars with properly operating vac brakes.

OK, I am not a fan of Hydroboost as I had my share of problems with them in my commercial fleet years ago, where NO maintenance issues were had with vacuum equipped vehicles. The only turbo Buick powered vehicle I had with the HD was also high maintenance due to leaks.

A race car should have NO booster, just reliable manual brakes. :smile:

Personally, I resent your attitude, and the way you have promoted your products here. By trashing all other products, and touting yours has proven to be a bad sales technique over the years.

 

[RickC]

An UPDATE on my brake problem

Thanks for all the suggestions. Despite very strong opinions, the diversity of those opinions actually helps when diagnosing intermittent problems.

I started by changing out all the vacuum lines except the 2 that run to the heat/ac controller in the car. The car runs better but pedal would still go hard without warning under a variety of conditions, nothing consistent. I was using 3/8 "emissions" line to the booster so decided to use "brake vacuum hose" per Nick's recommendation. Could not get "vacuum" line in 3/8 so I got 3ft of 3/8 power steering hose. I can't collapse it with pliers so I'm pretty sure its gonna hold up to engine vacuum. The next day going through the neighborhood 25mph no brakes.

Although the booster is new from Autozone decided to test it for leaks. Used my A/C vacuum pump on the booster and new hose. Pulled down to 30 inches and let it set. (The power steering hose did not collapse by the way :>) 10 minutes later still had 30 inches.

Wednesday exchanged the check valve with Autozone for another one. He took it off another new booster. He probably put mine back on after I left.

Thursday we had our first whole day without a brake problem.

I pray that I have finally identified a bad check valve on a new booster.

I will post again after a few days or if the brakes fail again.

Rick

 

[salvageV6]

I've had good success with the emissions hose, it's tough stuff. :smile:

I'm hoping you found the issue with the system.

There's probably thousands of T.R. cars now with vacuum systems on them at this time.

 

[bmackinnon]

We have new Hydroboosts.They work great, and will outlive any other brake system and even the car! Power Brake Service is THE O.E. distributor for the new units. They come ready to bolt on. Aluminum masters are available, and so are alum p/s reservoirs. As far as the whine in the pump, separating the returns back into the reservoir willl cure that. The alum reservoir has the two returns tapped in, and replaces the cheap factory plastic one.

OH NO!!!! Not him.....AGAIN!!!! Jeezus...

 

[bmackinnon]

Wednesday exchanged the check valve with Autozone for another one. He took it off another new booster.

Thursday we had our first whole day without a brake problem.

I pray that I have finally identified a bad check valve on a new booster.

:biggrin: Crossing my fingers as well!

 

[charlief1]

OH NO!!!! Not him.....AGAIN!!!! Jeezus...

I think (we'll see though) he got the message this time. Shane also said a few things to him.

 

[SGRIM]

O.K. BUT, the lead of the thread is that he could NOT find new Hydroboosts. NOW he has brake problems with the vacuum booster. Buick NEVER installed a vacuum booster on a turbocharged car. It didn't work then, why would it work now with used parts? How CAN the vacuum booster, with the low vacuum on these cars, possibly work right? They work O.K. in mild street driving, but not for high performance use. I have rebuilt thousands of those vacuum boosters, and know how to modify them for increased power. I have done those vacuum brake conversions, and the customers were never happy with them. We even added electric vacuum pumps. Still weak.
I was the first to install 7/8" wheel cylinders in those cars in 1987, because the dealers would send me S-10's to add power brakes on non-power S-10's. I discovered that the wheel cyls had to be changed to the smaller one with the addition of the booster. The Regal/G.N. has the same brakes as an S-10, but weighs 50% more. The vacuum booster used for these conversions is also the same as an S-10. So, now, with the S-10 booster, S-10 pads, calipers and rear brakes, how can this combo stop a car that is 50% heavier, and much, much faster?

We have been fine for 20+ years w/o a hydroboost system. Please chill with the sales pitch

 

[cruzn57]

I use Vac

on my race car, 236 duration, roller cam.
stops as good as it ever did with powermaster.
not debating any type setup,
just what works for me,

(oh, and its simple to install)

 

[captndave737]

Well I replaced the failed powermaster in a very overpriced parking garage at night with a vacuum system because it was the easiest cheapest solution and I was stuck.

The vacuum brakes work fine, just like before unless you have to stop fast!! The vacuum lines are all fine it's just the booster doesn't provide enough power. It's almost impossible to lock up the brakes, not that you want to lock them up but you can't have threshold braking without being able to do so with reasonably little effort.

Vacuum might be fine at the track where you stop every 1/4 mile with no one in front of you but driving in heavy traffic they suck!!! Towing my boat they're even worse.

Now that I'm home the hydraboost is going back on and either a new reservoir will solve the whine or I'll live with it but the car will stop as well as it accellerates.

I've had this car 23 years. New- braking was ok for 16 years 'till the powermaster failed, The next 4 years, Vacuum brake conversion with many change outs to try to find out what was wrong, brakes sucked. Last 3 years-hydraboost conversion DAMN, stops better than my BMW but whines a little.