Help: Vacuum Issues....
#1
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Join Date: Apr 2010
Location: Katy, Tx
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Help: Vacuum Issues....
I've been chasing a very bad brake issue which I believe to be directly related to lack of vacuum. My boost/vacuum gauge is reading 0-2" of vacuum and I have to press my brakes to the floor to get the car to even stop coming out of the driveway.
Things I have done so far:
- New Brake Booster and reservoir installed
- Brakes Bled and bled and bled again just to be sure
- Check valve on booster checked good
- Checked over and over for any leaks in vacuum lines (smoke test done as well)
- Compression test done on all cylinders (160 on all cylinders accept 1 of them measured 190psi)
- Leak down test done and all cylinders measure 20-27% (gauges verified on my Tahoe that measured >5%
- Dyno'd the car and still made 1k even with these issues.
When I did the leak down test, I found that the air was getting past the rings and all of the air was coming from the oil fill hole. This is a 416 with an procharger F1x. Looks like I need to have the motor looked at, but wanted some opinions on what's going on here. I even went and got HP Tuners Pro to monitor everything, but new to the software so no real help. Any help is appreciated.
-Justin
Things I have done so far:
- New Brake Booster and reservoir installed
- Brakes Bled and bled and bled again just to be sure
- Check valve on booster checked good
- Checked over and over for any leaks in vacuum lines (smoke test done as well)
- Compression test done on all cylinders (160 on all cylinders accept 1 of them measured 190psi)
- Leak down test done and all cylinders measure 20-27% (gauges verified on my Tahoe that measured >5%
- Dyno'd the car and still made 1k even with these issues.
When I did the leak down test, I found that the air was getting past the rings and all of the air was coming from the oil fill hole. This is a 416 with an procharger F1x. Looks like I need to have the motor looked at, but wanted some opinions on what's going on here. I even went and got HP Tuners Pro to monitor everything, but new to the software so no real help. Any help is appreciated.
-Justin
#7
11 Second Club
iTrader: (3)
243/251 115 here. Was having the same problem with the hard brake pedal after bleeding the system and it ended up being a bad brake booster. You need 10-12 on the vacuum for the brake booster and your not getting enough vacuum to properly work the brake booster.
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#8
11 Second Club
iTrader: (3)
Your only getting 2 inches of vacuum from the intake manifold?
#9
TECH Fanatic
iTrader: (14)
that is a really big camshaft, coupled with not perfect leakdown numbers. You might have to go to a separate vacuum canister to get enough vacuum to operate the brakes. what kind of vacuum are you getting at say, 1500rpm. any better. could be from retarded initial timing too. Using a hole in the throttle plate to get it to idle?