Bracket Talk
Loss of Vacuum

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https://drr.infopop.cc/eve/forums/a/tpc/f/80760912/m/3157024496

September 19, 2020, 04:56 PM
rarmbruster0001
Loss of Vacuum
When I parked my car two weeks ago, it had five pounds of vacuum at idle. Today, it has zero and the gauge won't move even if you rev the motor. Checked all the usual suspects: pump is pulling, oil pan, intake, and carb gaskets are tight, gauge is holding using a hand vacuum pump, and all lines are tight. The only change that was made in the car was a new set of rocker arms and adjusting nuts. Any help solving this problem would be appreciated.
September 19, 2020, 09:24 PM
Mike Rietow
Did you clean it yet?
September 20, 2020, 07:56 AM
Top355x
You had valve covers off ow about gasket there
September 20, 2020, 09:06 AM
Alaskaracer
Pan vacuum or manifold vacuum????


Mark Goulette
Owner/Driver of the Livin' The Dream Racing dragster
www.livinthedreamracing.com
"Speed kills but it's better than going slow!"
Authorized Amsoil Retailer
September 20, 2020, 10:12 PM
rarmbruster0001
Pan
September 21, 2020, 09:21 PM
Alaskaracer
So what's different from before? Need to recheck valve cover gaskets, and also pump. Many times the vanes in the pump will stick if they aren't cleaned periodically. My guess is that's what happened, is vanes are stuck...


Mark Goulette
Owner/Driver of the Livin' The Dream Racing dragster
www.livinthedreamracing.com
"Speed kills but it's better than going slow!"
Authorized Amsoil Retailer
September 24, 2020, 11:22 PM
rarmbruster0001
Part of the issue was the the new adjusting nut on the rockers wouldn't let the valve cover go completely down. I bought so thick gaskets and now I have half my idle vacuum back. Still not sure after tightening them down I have clearance. Pump is not supposed to need lubrication.
September 25, 2020, 07:34 AM
NC3x58
The pump could be pulling but a lot of times after sitting or after a few weeks of running, pull the hose off vacuum pump and spray brake clean down into it while motor is running.. Most Vacuum pumps won't pull vacuum if there is oil in there..


Nick Craig

1971 Camaro Split Bumper
376ci LS3
September 25, 2020, 07:40 AM
TD3550
High/low temp/humidity changes will milk up a pump.Whether it is a 3 or 4 vane pump. A lot clean the pump and a quick shot of WD. Good to go.
September 25, 2020, 10:36 AM
adv ET 266
Engine off, connect an HVAV Vac pump in place of your eng driven pump. Then search your engine from top to bottom and it will be talking to you.



2005 2000lb 4 link dragster
home brew 582 BBC Dart 355
1.058
2.98
4.629@149
6.094
7.310@185

September 25, 2020, 01:08 PM
Alaskaracer
Better yet smoke test it.


Mark Goulette
Owner/Driver of the Livin' The Dream Racing dragster
www.livinthedreamracing.com
"Speed kills but it's better than going slow!"
Authorized Amsoil Retailer
September 25, 2020, 04:08 PM
rarmbruster0001
Thanks for the help. How do I do a smoke test?
September 25, 2020, 04:54 PM
adv ET 266
One thing to consider, your leak is vacuum, smoke is a positive pressure test. Some vacuum leaks will not show up under a little pressure. Also getting “smoke” in an engine is not simple unless you have a real smoke tester.
Good luck



2005 2000lb 4 link dragster
home brew 582 BBC Dart 355
1.058
2.98
4.629@149
6.094
7.310@185

September 25, 2020, 05:48 PM
S/S Dart
Check for vacuum at the pump inlet fitting!! remove the hose with the pump running...if you have strong suction at the pump....your "leak is elsewhere...If you dont have strong suction at the pump inlet.. clean the pump as has been suggested....