Booster problems?

[Damicci]

SO get in my 94Q after leaving the misses and kid in the car running with A/C for about 5-10 minutes. Push on the brake and feel this weird push back. I put the car in drive and it starts to roll forward with the brake down.

I noticed the pedal was strangely stiff and required a decent amount of effort to press down. SO get home and start investigating. Car now has a rough idle. after a few temps at seeing if the pressure would change, i held the brake down firmly and then let go and turn the car off. Got the vibrating then slight gurgling sound in the engine bay. Look in the MS and the fluid is retarded low. Feel up the fluid check the reservoir on the passenger side and it's about normal. CHeck the pedal again no change. Take off Booster Vac line to Plenum and check valve seems to blow through ok. replace Booster side hose and now no more gurgling or rough idle. But the pedal is still very stiff.

Bad Brake Booster? If so where is the best place to purchase one?
Modified by Damicci at 2:35 PM 5/19/2008

[Damicci]

Well drove it to work and aI can hear a hissing sound when I press on the brakes. in side the cabin. Pretty sure it's a bad booster. If anyone know's where the best place is purchase a replacement I would appreciate it.

[maxnix]

http://www.infinitipartsusa.com

Sure it's not a check valve or a misconnection?

[Damicci]

How would I determine a misconnection? \line comes from:BBooster -> Check valve -> plenum. I'll try disconnecting the line and see if there is vacuum pressure through the valve, I am pretty sure there is though.

I also checked That site and couldn't find what I was looking for. Unless there is another name besides Brake Booster?

[maxnix]

Probably another name. Always best to call with VIN in hand.

[Damicci]

Cool thanx.

[Q45tech]

To my knowledge we have never replaced a brake vacuum booster in 15 years.

Lot of vacuum hoses and master cylinders, however. Who knows there has to eventually be at least one.

What is hot idle plenum pressure 18-20" HG below atmospheric if not you have a leak.

[Damicci]

Yeah checked again yesterday and there is a distinct hissing sound inside the cabin when the car is on and the brakes are depressed. goes away when you let the brakes go.

Any tips on replacing the booster. I found a used one on eBay, and I have the FSM just wondering if anyone has done this before.

Q45Tech>This car always seems to be a special case. especially with 193K miles something are bound to go haywire.

[maxnix]

Unless you used a sharp instrument to poke your diaphram, still not certain it's your booster.

Tech's car has over 300K, he's seen higher mileage ones.

Never heard of anyone in 7 years on this board replacing a Q45 brake booster.

Beware of eBay.

[Damicci]

I am open to suggestions. I don't have a way of measuring vacuum right now but i did try spraying carb cleaner in the booster area to see if there was a change in idle and nothing.

[Damicci]

Quick update, the booster was bad. Replaced it today and now the brakes feel normal. The old booster you could blow air right through it.

[maxnix]

Thanks for the update. Thatis a first. Damaged diaphragm or just failed?

[Damicci]

Not sure, I think diaphragm, It was still difficult to blow air through it but it still went through either way.

Was a pain in the say to reach the mounting bolts for the booster but I am happy everything is working. need to bleed the brakes again though.

[Raxephon]

I actually had to replace mine in the '92 about a month ago.

I initially thought it was the master cylinder, but after replacing it with a brand new one the problem continued to persist.

So I pulled the booster, replaced it, and slapped the new master cylinder back on.

Since then I haven't had any brake problems.