Help.. brake booster gone crazy

[72.5 Vette]

72 C10 with 305 TPI on the road for 2 years now it's blowing out the vacuum line at the booster ! Causing the brakes to go beyond hard. Good hose ,good vacuum,good valve , no backfire, good booster as tested by direction's on site. ????

 

[Maniacmechanic1]

Check the Engine motor mounts and make sure they are good.
Any doubt replace them along with the transmission mount.

Check ignition timing.
With the Spark timing connector unplugged set the TPI 305 Chevy to 6 degrees BTDC.

 

[Grumpy]

http://garage.grumpysperformance.co...breather-hole-in-valve-covers.2005/#post-5328

be sure the PVC is correctly installed and functional and the vacuum valve on the brake booster is connected to plenum vacuum and its only allowing a single directional air flow.

 

[72.5 Vette]

Check the Engine motor mounts and make sure they are good.
Any doubt replace them along with the transmission mount.

Check ignition timing.
With the Spark timing connector unplugged set the TPI 305 Chevy to 6 degrees BTDC.

Thanks mechanic1 !! You where spot on who would have thunk it ....bad motor mount on drivers side ...torqued just right to pull the vac hose from the booster!!
Thank you too Grumpy checked the PVC & lines first thing

 

[Grumpy]

yeah the first thought I had was check the motor mounts ,and hose clamps,
but Brian had already suggested to check that option.

 

[Maniacmechanic1]

Thanks mechanic1 !! You where spot on who would have thunk it ....bad motor mount on drivers side ...torqued just right to pull the vac hose from the booster!!
Thank you too Grumpy checked the PVC & lines first thing

Your Welcome.
I have seen it happen before.

 

[Loves302Chevy]

Great diagnosis. I wouldn't have thought of that. At least, not at first.