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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHManometer - cheap vs expensive what to buy
Leading reported evidence
Check every connection and they're all secure
Performed · outcome unconfirmed
No successful repair reported for this finding.
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Reported fixes
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Unsuccessful attempts
1
Discussions
Read evidence and context
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Discussions that performed work without a confirmed outcome
1
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Performed · outcome unconfirmed
I double checked every connection and they're all secure.
Leading evidence: 'Check every connection and they're all secure' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'air oil separator' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Adjust gas pilot lights' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Discussions that performed work without a confirmed outcome
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Performed · outcome unconfirmed
Checked the vacuum on the 2003 986 S this morning--measured right at 5.0 in/H20.
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Performed · outcome unconfirmed
I just replaced my AOS and all the hoses connected to it with the FCP Euro kit.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
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1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Suggestion
You can also just run a simple test by removing your oil cap and if it's tough to get off due to excessive vacuum and the engine sputters once its removed, you have a vacuum problem and most likely a faulty aos.
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
air oil separator
No successful repair reported for this finding.
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Identified cause
1
Suspected cause
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Reported fixes
Read evidence and context
Discussions that suspect a cause
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Suspected cause
You can also just run a simple test by removing your oil cap and if it's tough to get off due to excessive vacuum and the engine sputters once its removed, you have a vacuum problem and most likely a faulty aos.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
35 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261026T133652Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
I would like to purchase a manometer to quickly be able to check and monitor AOS health . I have an OEM AOS in my Boxster S and a UAOS in my 996 C4 . Looking online on Amazon as an example they are available from $29.99 to $200.00 + . As a tool that will only be used once or twice a year can the inexpensive do the job ?
Also there seems to be two different styles . They are a " one nipple " vs a " two nipple " design . So one hose vs two hoses . I assume either can be used ? Anyone have a brand preference or model number preference ? I currently have no known issues but would be nice to check randomly as I want to .
But what about what LN offers? I mean it's "developed" by Tony Callas. Oh, but it's not a manometer, it's a "Crankcase AOS Vacuum Measurement Tool" so that must be better, right? And on sale for only $399! (I gotta get two!
).
Seriously, it's the crappiest manometer on aliexpress at $29 each. But let's hear from the LN fanbase, maybe I'm missing something.
It's amazing how similar the $399.00 CR Tools version is to the $79.00 Pyle version.
https://rennlist.com/forums/996-foru...l#post15500916
And the $39.00 Risepro.
That�s the beauty of the free market. Those willing to do their research and a bit of work can save a pretty penny. Others can opt to spend the extra cost for convenience giving LN extra profit to invest in their more pertinent products and solutions. win win
I am of the more practical type as I enjoy the research and tinkering my garage. $40 CAD manometer and about same price for the oil cap from my local dealer.
It's a tool that you can use to test your aos by measuring vacuum. You remove the oil cap and screw in the cap/ tube to manometer and run the test while the car is running.
You can also just run a simple test by removing your oil cap and if it's tough to get off due to excessive vacuum and the engine sputters once its removed, you have a vacuum problem and most likely a faulty aos.
No need to spend alot of money on it. If I knew there were cheaper manometers that worked well, I would have bought one instead of the dwyer for $100.
Our fascination with the exquisite never ceases to amaze me.
I have this to measure crankcase vacuum. Takes me about 20sec to get a reading and batteries haven�t gone out in over three years of use.
Maybe I should be selling these for $400�.
What?! and not recommend buying the LN/Callas "
Crankcase AOS Vacuum Measurement Tool" for the low "on sale" price of just $399? What happened to the RL tradition of only recommending the site sponsor's expensive "solutions"? Say it with me, "one and done".
Don't know what to tell you...
Some guys like expensive gadgets. I just needed to test my motorsports aos to see if it was failing. It was, so I got a UAOS. Probably never need to use the manometer again. There is your one and done.
Probably the most useful tool worth the money is the durametric software. Use it all the time.
Are there any instructions for how to measure, I have a 986. Some drill a hole in a spare oil filler cap for the barbed hose connector while others have a small hole and/or a large hole drilled for measuring at idle vs WOT. Are no downloadable instructions on the LN site or from Tony Callas.
@Coussa
guess we share a typical rennlist library lol
My meter�
There�s now a video on YouTube: �The Callas Method� - measuring crankcase vacuum with CR Techs Manometer.
Not much meat in the video but I do see that his oil filler cap doesn�t have any extra holes in it, other than one for the barbed connector.
I borrowed an analog vacuum gauge last year to check my 996's crankcase pressure. Wanted my own and bought a used filler cap off ebay, about $12 as I recall. Went no further till this thread. Bought used digital manometer off ebay for $18. One more tool in the maintenance arsenal.
Checked the vacuum on the 2003 986 S this morning--measured right at 5.0 in/H20. Currently have about 80,000 miles on her. I have a spare AOS on hand. I wonder how long the original will last.
since you have a spare in hand it usually doubles the life of the one in use.
Unless you carrying the spare in the trunk, and remove it to fit your wife's makeup bag in the trunk.
Then pray because your doomed.. BTDT...
I just replaced my AOS and all the hoses connected to it with the FCP Euro kit. Everything seemed fine upon startup. I went to take the oil cap off and the engine drops about 100rpm and sounds like it has hot cams. The cap isn't hard to remove but there is some vacuum coming from the oil filler neck. I double checked every connection and they're all secure. Am I looking at redoing the AOS? I'll have to order a manometer, but tell me some good positive news in the meantime.
My car, 2003 Coupe, does pretty much what you described. Remove the cap and the engine rpm drops slightly with it running slightly rough. My manometer reading is 5" water.
Follow-up....ebay used two-port manometer arrived ($19.26 with tax), combined with $11.22 used oil cap from ebay, and a barb fitting from Lowe's...total of $34.75. Unit functions perfectly and looks professional (Well, appearance IS everything!) I got to thinking about some of the tools we accumulate. Even if you are not aggressive at DIY, being able to read/reset codes, check crankcase vacuum, etc. is easy and can save a lot of "diagnostic" charges at your indy or dealer. And it continually increases your familiarity with your car(s).
A bit older post, but I didn't see clarification.
Single barb fitting with no other holes, or holes sealed, (measuring with the system sealed) is to measure crankcase vacuum and AOS function.
Measuring with additional holes in the cap,of specific size, is to measure blow by.
Oil filler cap should have single hole with single barb fitting. My used manometer used 1/8 inch barb fitting. Drilled and tapped filler cap for pipe thread and screwed in fitting. Be sure manometer is set to inches H2O. Put cap on engine and start, then read value on manometer.
I know, I was referring to the fact that some caps shown have additional precision holes drilled, which are used to measure Blow By (different from crankcase vacuum and AOS function).
There are two tests that can be done with slightly different cap configurations.
https://rennlist.com/forums/996-foru...w-by-test.html
