Hi all,

Why do you need to have the power brake filter between the carb and the brake booster? What does it filter out? I've heard things about the crankcase gases, but since the engine is sucking rather than blowing, I don't see how this could be true.

So, what's the purpose of it?

 

I think you might be refering to the one-way valve that is installed inline. This prevents backflow of the vacuum pressure back into the booster to maintain suction and a functioning booster when throttle position decreases suction. Without that valve, the booster vacuum suction reserve would drop down sometimes to about 5in. instead of the normal aprox 18 operating range.

 

The one way valve I believe is in the booster itself. The filter I'm referring to is at www.napaonline.com, part number BK 6755136. This is the device I'm wondering about.

 

I have never seen one before but an posstive it has to do with smog emissions (just like the charcol canister. They don't what for any reson fuel fumes entering into the booster and then escaping unburned into the ozone layer Could be requred if you are subjected to any kind of visual smog check with that year car.

 

I understand the theory, but I don't understand how that works in practice. I mean, the engine sucks on the booster, it doesn't blow into it - does it? If so, under what circumstances would that happen?

 

It is an air filter for the engine. Nothing more.... nothing less. Most people overlook the fact that air is drawn through the Power brake booster. That air can contain dirt, sand particles or dust. It is a small amount true, but Mfg's have to design for all climatic conditions.

Extremely dusty conditions could draw enough material into the engine to damage it,,,,especially if the vehicle was operated in a dusty enviroment every day. Not likely with our cars...but think about what a Farmer's pickup truck goes through evry day.

And yes...they do clog up. Do a search for " Booster filter" and you will find a couple of members who have had strange " Booster" problems that were fixed by replacing this simple $8 filter. Clogged with dirt...the booster can't draw enough vacuum to recover in time in stop and go traffic.

Edit: Spelling

 

Same basic reason why we need a 1 way valve on the booster to prevent air to be backfilled into the booster to reduce vacuum. My theory is that and back pressure against the one way valve with fuel fumes may deteriorate it and cause failure (thats my theory and assumption- I'm not an expert here. Chickenmans theory sound solid also)

 

its a air filter.


when you push the brakes, air goes into the brake booster.... but when you let go, the engine starts sucking the air out of the booster, into the motor.

this air has never been filtered.. so before it goes into your intake manifold, it goes thru a filter.

its not to keep fumes or anything like that contained in the motor... its just there to keep you from sucking dust and sand off your boots (by the inlet for the brake booster) and into the motor....

 

Ah ha! Now I get the whole idea about the flow of air, thanks everyone.

Is there anything special about the air filter at all? They seem impossible to come by here and I don't feel like going to the trouble of importing one so I might see if I can get some other kind of filter as a replacement. I presume an inline fuel filter would not be appropriate?

 

alot of new cars run them now actually, ALOT. esp trucks. i know at toyota (im a toyota tech) we have bunch of cars with em. dont want any dust getting on the diaphram of the booster, if you unplug the vaccume line going to it wrong the diaphram could tear. quite sensative, not on out thirdgens do you need that filter or worry about the booster, it goes when it goes. 99% of the time a booster goes bad in our cars its nothing we did to it.

 

A fuel filter would probably be fine, but here's a thought. Do you have any Holden dealers near you? ( FYI North Americans...Holden is the Australian\New Zealand division of GM ).

GM uses a lot of the smaller parts for years on end.....Global wide. I'm betting that if you go to a Holden parts dealership, you can find the exact same air filter or something very close to it. Pop open a few hoods in the used car lot or a wreckers.

 

I did phone up the Holden dealer and spoke to a guy in parts, but when I described the part I wanted he didn't seem to know what I was on about, saying he's never seen or sold one. I might try a generic inline filter since I don't want to spend a lot of time looking around for a "non-critical" part.

I wouldn't mind buying one from the US though, but the places I've come across don't ship outside of the USA. Unless anyone can tell me of a company that does...

 

See if your aftermarket suppliers carry Motormite. The part you want is Motormite # 80195.

Here's a link. Print the picture out and take it to a local Parts supplier. Look for an " Old fart" . They're usually the best countermen.

Brake Booster Filter

 

That should give me something to go on, I hope!