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Registered
Join Date: Oct 2000
Location: Burlington, ON, Canada
Posts: 7
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DYI Leak-down test
Anybody that can post info on doing the leak-down test? I have the Bentley and it says it's better to leave it to the experts (at the garage of course!). Thank you, please respond to gstroe@cogeco.ca.
George |
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05-12-2002, 05:40 PM
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Registered
Join Date: May 2000
Location: Los Alamos, NM, USA
Posts: 6,044
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Welcome George, You'll need a source of compressed air, a leakdown test rig, sparkplug tools, etc. Use the search function button in the upper right of the window. Type in "leakdown" for the key word, "pbs911" for the user name and search in the "Porsche 911 Technical Forum". This should lead you to a good thread with info, pictures and leads to further information. Cheers, Jim
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05-12-2002, 08:09 PM
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Registered
Join Date: Oct 2000
Location: Burlington, ON, Canada
Posts: 7
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Dear Jim, I've checked using "leakdown" as keyword, got a lot of interesting posts including your own but nowhere how to actually do the test yourself. I know you need a compressor (have one) and two manometers interconnected (how?). So are there instructions anywhere on how to actually do it yourself? This talk of valve adjustment made me think, there is no noise on my car but I am sure the valves were not adjusted during the past several years; but the car mostly sat instead of running. Thanks,
George |
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05-13-2002, 04:35 PM
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Registered
Join Date: Jun 2000
Location: bottom left corner of the world
Posts: 22,733
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Hi George.
A compression test is the best way to find if you have a problem and a leakdown test is used to determine where the problem lies, meaning exhast valves, rings and intake valves. Compression testers can be bought from any automotive parts and accessories place. Bill '79SC |
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05-13-2002, 05:32 PM
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Registered
Join Date: May 2000
Location: Los Alamos, NM, USA
Posts: 6,044
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George, It's all there (how to do it, a link on how to make a leakdown test rig, etc.) under a thread entitled "How to do to a leakdown test". Search under both (put both pieces of information in at the same time) keyword "leakdown" and the user name "pbs911". I'd paste the link except that the browser I'm using won't paste it! Cheers, Jim
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05-13-2002, 06:09 PM
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Registered
Join Date: Dec 2000
Location: McLean, VA
Posts: 1,155
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George,
Before you run compression & leakdown tests, best to try to free up what has become gummy while your car has been sitting in the garage. Run 1/2 tank of gas with a bottle of Techron. Spririted driving, with lots of upper rev range work under load. Short stints [up to full op temps] are better than three hours on the freeway. Gum and coke deposits are most likely in a stored engine, and they will give misleading results. Try to free things up with the Techron before testing. Will give you more accurate results. BTW, while the manometer approach is scientifically correct, one critical aspect of a leakdown performed by a specialist 911 tech is the listening part - listening for where the leakage is passing. There is a surprising amount to be learned from gas noises in the intake and exhaust maniflolds while the test is in progress.
__________________
Tony K '89 944T 944 SuperCup Champ 2004 & 2005 '85 Carrera - Sold [sob] TrackVision 944Cup The 999 Site |
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05-13-2002, 06:31 PM
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You do not have permissi
Join Date: Aug 2001
Location: midwest
Posts: 39,870
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Remember both of those are only going to tell you the sealing condition of the combustion chamber itself: rings, valve seating, head gasket.
It won't show worn valve guides, resessed valves, worn springs, stretched chain, worn bearings, leaking intake manifold gaskets etc.. as well as anything fuel or ignition. Use a 3/4inch breaker bar on the crank bolt with a strong friend holding because at TDC that engine will want to turn. |
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05-13-2002, 09:37 PM
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