Valve Problem?
02-11-2011, 06:10 AM
#16
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Join Date: Jul 2002
Location: Kissimmee, Fl, USA
Posts: 1,942
Re: Valve Problem?
A vacuum gauge by itself is a good tool to have but it has limitations when used on cams with a lot of overlap. There are all orts of needle fluctuations, etc, that don't lead stem from actual problems.
I think a leak down tester is an essential tool, even if it only provides static data...
I think a leak down tester is an essential tool, even if it only provides static data...
02-12-2011, 12:39 AM
#17
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Join Date: Feb 2010
Location: Pittsburgh, PA
Posts: 66
Re: Valve Problem?
1 glaring problem with only using a vacuum gauge. If you know what level it is supposed to be and it's lower, how do you know what is causing it to be lower? There is literally 10s of feet of vacuum hose, connectors, canister etc that could be leaking.
If you were to use a leakdown tester, it would pinpoint a definite problem with valves, head gasket or rings.
But beware it's use if you interpret the results wrong.
One other thing, if you suspect a valve is leaking. It would show up on a compression test.
Both leakdown and compression testers are available for loan at local autoparts stores.
If you were to use a leakdown tester, it would pinpoint a definite problem with valves, head gasket or rings.
But beware it's use if you interpret the results wrong.
One other thing, if you suspect a valve is leaking. It would show up on a compression test.
Both leakdown and compression testers are available for loan at local autoparts stores.
A vacuum gauge by itself is a good tool to have but it has limitations when used on cams with a lot of overlap. There are all orts of needle fluctuations, etc, that don't lead stem from actual problems.
I think a leak down tester is an essential tool, even if it only provides static data...
I think a leak down tester is an essential tool, even if it only provides static data...
You guys are missing my point. You can buy a vacuum gauge for $12, hook it up through the accessory vacuum port, and have readings in a couple minutes. If a problem shows up on the vacuum gauge the a leak down test would be my next step. If a problem does not show up, you have verified good mechanical condition of the motor quickly and cheaply and can move on to the next step in diagnosis.
Also I may have missed it, but I don't think the OP has a after market cam. If there is a aftermarket cam, of course normal readings for it would be different from a stock cams normal readings.
02-12-2011, 10:32 PM
#18
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Thread Starter
Join Date: Mar 2010
Posts: 457
Re: Valve Problem?
We are already assuming I have a vacuum problem because my fuel gauge is bumping while idling, showing a difference in vacuum pressure at some point during the firing cycle. It's pretty consistent, but you are right, I should grab one just in case and check it. I just thought you were trying to use it as a replacement for the leak down test. But no, what you are saying makes sense. 
Good call.
Good call.
02-13-2011, 04:15 AM
#19
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Join Date: Feb 2010
Location: Pittsburgh, PA
Posts: 66
Re: Valve Problem?
Oh sorry I didn't see the fuel pressure part. Not that I didn't read before posting I just must of missed it.
How many PSI swing is there? 1 PSI = about 2" of vacuum, If that helps any.
How many PSI swing is there? 1 PSI = about 2" of vacuum, If that helps any.
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