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Loss of Vacuum
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DRR Trophy
posted
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.
 
Posts: 51 | Location: Kentucky | Registered: February 26, 2011Reply With QuoteReport This Post
DRR Top Comp
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Did you clean it yet?
 
Posts: 9398 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
DRR Trophy
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You had valve covers off ow about gasket there
 
Posts: 401 | Location: Natick MA | Registered: November 15, 2017Reply With QuoteReport This Post
DRR Pro
Picture of Alaskaracer
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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
 
Posts: 1504 | Location: Back home in Alaska! | Registered: February 13, 2011Reply With QuoteReport This Post
DRR Trophy
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Pan
 
Posts: 51 | Location: Kentucky | Registered: February 26, 2011Reply With QuoteReport This Post
DRR Pro
Picture of Alaskaracer
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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
 
Posts: 1504 | Location: Back home in Alaska! | Registered: February 13, 2011Reply With QuoteReport This Post
DRR Trophy
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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.
 
Posts: 51 | Location: Kentucky | Registered: February 26, 2011Reply With QuoteReport This Post



DRR Trophy
Picture of NC3x58
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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
 
Posts: 410 | Location: Ohio | Registered: December 28, 2013Reply With QuoteReport This Post
DRR Sportsman
Picture of TD3550
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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.
 
Posts: 1409 | Location: Under a Truck | Registered: August 23, 2013Reply With QuoteReport This Post
DRR Elite
Picture of adv ET 266
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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

 
Posts: 12174 | Location: 33463 | Registered: February 04, 2004Reply With QuoteReport This Post
DRR Pro
Picture of Alaskaracer
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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
 
Posts: 1504 | Location: Back home in Alaska! | Registered: February 13, 2011Reply With QuoteReport This Post
DRR Trophy
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Thanks for the help. How do I do a smoke test?
 
Posts: 51 | Location: Kentucky | Registered: February 26, 2011Reply With QuoteReport This Post
DRR Elite
Picture of adv ET 266
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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

 
Posts: 12174 | Location: 33463 | Registered: February 04, 2004Reply With QuoteReport This Post
DRR Trophy
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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....
 
Posts: 232 | Location: North Royalton Ohio US*** | Registered: January 08, 2001Reply With QuoteReport This Post



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