DIY Compression Testing
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Joined: Jul 2008
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From: Miami, FL
Originally Posted by fadiss2k,Feb 1 2008, 12:31 PM
no, i got an average of 235 all across. 240 is the magic number you supposed to be looking for i think, but 235 is still good for an 8 year old car.
Thanks
Fadi
Thanks
Fadi
any variation of 20psi or more and i would be concerned.
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Joined: Jul 2008
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From: Miami, FL
Originally Posted by Seattle2k,May 1 2008, 01:07 PM
a little off topic.. when I bought my S, I had a mobile vehicle inspector come out to run through the car. He offered to do a compression test, but said it wouldn't be necessary, unless his vacuum test came out with poor readings.
I had never heard of this vacuum test before, so I want to run it past you guys. I don't know the specific details as to what was carried out, so hopefully my description rings a bell...
Essentially, he hooked a vacuum guage to some line, and blipped the throttle a few times. Based on how much vacuum was registered, and how fast the needle moved under certain conditions, he said he was able to determine if the valves were sealing properly. He said the vacuum/valve test would give poor results, if the cylinders also had low compression.
Anybody heard of this type of valve/vacuum test? Is it BS?
I had never heard of this vacuum test before, so I want to run it past you guys. I don't know the specific details as to what was carried out, so hopefully my description rings a bell...
Essentially, he hooked a vacuum guage to some line, and blipped the throttle a few times. Based on how much vacuum was registered, and how fast the needle moved under certain conditions, he said he was able to determine if the valves were sealing properly. He said the vacuum/valve test would give poor results, if the cylinders also had low compression.
Anybody heard of this type of valve/vacuum test? Is it BS?
a vac gauge will tell you if something is wrong, but it dosent necessarily need to be poor cylinder compression. a compression test is more "direct" in that sense.
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btw to anyone that had the end get stuck down in the hole, like overst33r and me lol, i used red thread locker (locktite) on it and screwed the hose in it let it sit for like 30 mins and came back and unscrewed it with the hose. that is easy and you wont ruin the bit with a file and hammer....
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From: NoVA
Originally Posted by AP_ONE,Feb 22 2008, 12:18 AM
You need not crank it 8-9 times, A solid 5-6 turns will be enough to give you a proper reading.
Also you want to let your car warm up b4 you do the test and cold results will be lower then hot results. This is very important.
Be sure to hold pedal to floor while cranking it over till you stop.
Also you want to let your car warm up b4 you do the test and cold results will be lower then hot results. This is very important.
Be sure to hold pedal to floor while cranking it over till you stop.
what he said i guess technically you could do it without warming it up, but just expect to get lower number
Joined: Sep 2004
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From: Tampa, FL
Originally Posted by Gamble,Sep 10 2009, 03:37 PM
Is it completely necessary for the engine to be warm? I'm testing this after a nasty overrev and I really don't want to run the engine so it can warm up.