Leak down test not required?
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From: Atlanta
Leak down test not required?
I called two places today (dealer and independant) to get a leak down done for a PPI on my car I'm selling and both places denied me and told me its a waste of money. "The car is OBDII, if there was something wrong, the check engine light would be on." I guess I never thought of it that way, but they are right to a point. Im sure a cylinder could be getting close to high leak down percentages and still not have a CEL on. What do you guys think?
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From: Atlanta
I agree, but this is the request of the buyer. In reading my PMs and emails and a lot of threads, it seems that a leak down test is the preferred test among buyers, I just never thought about it much from an OBDII perspective. Of couse if I mention it, it will loook like I'm just hiding something, or not wanting to get it done.
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From: Kingston, NY
You want a leakdown test, not a compression test. The leakdown test will give you an idea of the health of an engine. This is particularly important on the 993 where the exhaust valves pit easily and lose their seat concentricity and begin to leak. OBD2 will not tell you mechanically that anything is wrong, it will only look at the symptom of a problem. ie CEL for SAI port BECAUSE the valve guides are worn and leaking, plugging the ports.
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Unless you knew the previous owner and car from new, I would get a leakdown and compression test. It is cheap insurance especially if did not know how car was driven and maintained in the past.
Last edited by amfp; Mar 25, 2007 at 12:08 PM.
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From: NATICK MASS.
A leak down test is far more informative than compression test. I strongly recommend having one done by any perspective 911 buyer. Its a bit time consuming on a 993, so that may explain the service facility's
reluctance to do it. I would fine someone that will.
Good luck, Jerry
reluctance to do it. I would fine someone that will.
Good luck, Jerry
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From: Tampa
Originally Posted by J.PELLEGRINO
A leak down test is far more informative than compression test. I strongly recommend having one done by any perspective 911 buyer. Its a bit time consuming on a 993, so that may explain the service facility's
reluctance to do it. I would fine someone that will.
Good luck, Jerry
reluctance to do it. I would fine someone that will.
Good luck, Jerry
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Thread Starter
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From: Atlanta
So which one would occur first on a OBDII car? A CEL or bad leak down readings? In otherwords could a bad leak down catch a potetntial problem that OBDII hasnt recognized yet? I know OBDII is highly sensative. I think that is their point. I completely agree with pre OBDII cars.
And what is considered good/ bad readings?
And what is considered good/ bad readings?
Originally Posted by Geoffrey
You want a leakdown test, not a compression test. The leakdown test will give you an idea of the health of an engine. This is particularly important on the 993 where the exhaust valves pit easily and lose their seat concentricity and begin to leak. OBD2 will not tell you mechanically that anything is wrong, it will only look at the symptom of a problem. ie CEL for SAI port BECAUSE the valve guides are worn and leaking, plugging the ports.
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From: NATICK MASS.
A good leak down done correctly will expose engine issues before the same engine begins to misfire. It is the presence of misfires that will usually trigger the dreaded CEL. As for what is a good vs bad leakdown result can vary depending on many factors. We generally want to see leak down numbers under 10% but more importantly, the results should be fairly consistent from one cylinder to the next.
Happy motoring, Jerry
Happy motoring, Jerry
