xm 80 Posted July 5, 2017 Share Posted July 5, 2017 so i finally had some time to do a compression test on my engine....but i'm abolutly confused about the readings!?!?! here is what i was reading with the oil temp at around 80°C ("warm engine"): #1 225psi #2 220psi #3 227psi #4 223psi #5 220psi #6 220psi wasn't expecting this high readings at all, since i guessed that the head gasket was blown????!!!! as of shop manual these readings are way to high (new should be around 160psi IIRC). so my question is, what could cause this??? here are some things i noticed that might also indicate a trouble: - if i remove the PCV hose (intake side) from the intake and put my finger over the hole of the intake the idle rpm drops abouut 100-200 rpms -had some oil in the intake, not much, but it was visible to the eye also took a pic of the spark plugs...will post that later. since my dad own an endoscope i also gave it a try and had a closer look at the pistons...and they looked sort of "clean" to me??? they some darker patches (looked like rust...brownish) and some brighter spots....which looked like white or yellow-ish. any thoughts? car still idles a bit rough and have some misfiring (i would say), but this could be of another issue with the ignition timing (still have to check that too). Quote Link to comment Share on other sites More sharing options...
Dnk Posted July 5, 2017 Share Posted July 5, 2017 (edited) Is you car an NA ? 160 psi or more is for the gte turbo, 190 psi or more is for an NA Edited July 5, 2017 by Dnk (see edit history) Quote Link to comment Share on other sites More sharing options...
ripped_fear Posted July 5, 2017 Share Posted July 5, 2017 As above the compression can go up with age from what i have been told, think this is down to carbon deposits, and its not uncommon to see a healthy TT lump have numbers around 180 now, so logic would imply maybe an NA could be in the low 200's? Quote Link to comment Share on other sites More sharing options...
rider Posted July 5, 2017 Share Posted July 5, 2017 I'd check another engine using the same gauge as it'd be an act of faith to just accept what a gauge tells you in absolute terms unless it has been recently calibrated. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted July 5, 2017 Share Posted July 5, 2017 My TT used to test in the region of 200psi, not something i would worry about. Quote Link to comment Share on other sites More sharing options...
xm 80 Posted July 5, 2017 Author Share Posted July 5, 2017 thanks guys soooooo much!!!!! i've been searching around the web and also came up with the carbon deposits.....make sense, since i found a lot of carbon/oil stuff in the intake manifold, all the way to the intake valves! @DNK: sorry i forgot to mention that it's a NA Supra. it's also strange....i found varies numbers of what is normal for a NA engine...but i guess it should be fine then @ider: i checked the gauge afterwards at work,....both the low and the high readings where correct! Quote Link to comment Share on other sites More sharing options...
rider Posted July 6, 2017 Share Posted July 6, 2017 People seem to rave about this stuff as a fuel additive that cleans (including carbon deposit stripping) and lubricates the upper parts of the engine and injectors. I even bought some myself. https://www.google.co.uk/search?q=Lucas+Oil+Upper+Cylinder+Lubricant+%26+Injector+Cleaner+&sourceid=ie7&rls=com.microsoft:en-GB:IE-ContextMenu&ie=&oe=&gfe_rd=cr&ei=uDZeWZO6EYb38AeVvbjABg#q=Lucas+Oil+Upper+Cylinder+Lubricant+%26+Injector+Cleaner&tbm=vid&spf=1499346635648 Quote Link to comment Share on other sites More sharing options...
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