enough vacuum?
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Joined: Jul 2002
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enough vacuum?
Assuming you have a stock cam, those numbers seem low. I think you should get 18" to 20" of vacuum at idle. How does the engine run?? Do your power brakes still work OK?? Where are you measuring the vacuum?? Sometimes the vacuum ports in the intake manifold and/or carb spacer get clogged up and give you an incorrect reading (as well as low vacuum to PCV, brake booster, etc.).
Good luck,
Carl
Good luck,
Carl
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Senior User
Joined: Aug 2000
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enough vacuum?
i took the hose off the vac canister. i have a suction noise where the brake pedal rod goes through the firewall. could this cause it to die when its cold and the gas pedal not tapped sometimes?
Senior User
Joined: Jul 2002
Posts: 160
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enough vacuum?
The noise you describe coming from the brake pedal rod sounds like you have a bad power brake booster.
Crimp of the vacuum hose going to the booster(or take it off and plug the end)and see if that changes your vacuum reading and/or how the engine runs.
I would take the vacuum reading directly off the port or "T" in the back of the manifold (I assume it has one).
Carl
Crimp of the vacuum hose going to the booster(or take it off and plug the end)and see if that changes your vacuum reading and/or how the engine runs.
I would take the vacuum reading directly off the port or "T" in the back of the manifold (I assume it has one).
Carl
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Senior User
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enough vacuum?
[updated:LAST EDITED ON 10-Sep-02 AT 08:05 PM (EST)]today after running for a half hour, i measured the vac again and got 15" i crimped the brake booster hose and got 16-17". the noise from the brake push rod stopped when i crimped the hose. it also idled slower and smoother. does this mean my booster is going to leave me soon? should i get a new one, rebuilt, or from a junkyard? how hard is it to replace it?
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Joined: Jul 2002
Posts: 160
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enough vacuum?
Yep, youv'e got a bad booster.
I had a booster leak like that for over a year that I owned the vehicle, and the guy that bought it from me is still driving it that way over 6 months later.
But it's best to go ahead and replace it. If it completely goes out your brakes will be VERY HARD to mash - you'll practilly have to stand on the pedal to get it to stop, and this would not be good in an emergency situation.
I would price a rebuilt unit through your local parts store. If that's too costly you may have to go the used route.
They are easy to replace. Sometimes you can remove the master cylinder and pull it out of the way far enough to replace the booster without removing the brake lines or having to bleed the brakes.
Some places sell the booster and master cylinder as a unit but i'm not sure on your truck.
Good luck
Carl
I had a booster leak like that for over a year that I owned the vehicle, and the guy that bought it from me is still driving it that way over 6 months later.
But it's best to go ahead and replace it. If it completely goes out your brakes will be VERY HARD to mash - you'll practilly have to stand on the pedal to get it to stop, and this would not be good in an emergency situation.
I would price a rebuilt unit through your local parts store. If that's too costly you may have to go the used route.
They are easy to replace. Sometimes you can remove the master cylinder and pull it out of the way far enough to replace the booster without removing the brake lines or having to bleed the brakes.
Some places sell the booster and master cylinder as a unit but i'm not sure on your truck.
Good luck
Carl
