Tom Posted October 28, 2005 Share Posted October 28, 2005 I searched on MKIV as I could have sworn it was on there but couldn't find it, how do you do it? what do you need and how long does it take to do? TIA Tom. Quote Link to comment Share on other sites More sharing options...
tbourner Posted October 28, 2005 Share Posted October 28, 2005 I could do with learning this too, sounds easy. Quote Link to comment Share on other sites More sharing options...
JohnA Posted October 28, 2005 Share Posted October 28, 2005 If you can change your spark plugs, you can do a compression test. Just go to Halfords, get a tester (with "peak hold") and read the instructions at the back Quote Link to comment Share on other sites More sharing options...
TLicense Posted October 28, 2005 Share Posted October 28, 2005 LOL I could do another how to:- Compression test, but I think if I even thought about opening the bonnet on the car within the next week or so the girlfriend will straight out kill me. Quote Link to comment Share on other sites More sharing options...
Tom Posted October 28, 2005 Author Share Posted October 28, 2005 Ok, i'm on my way to halfords! Quote Link to comment Share on other sites More sharing options...
Pete Posted October 28, 2005 Share Posted October 28, 2005 Dunno about the Supra, but for the Pinto in my kitcar you disconnect all the plugs (remember the order) test one cylinder at a time, remove sparkplug, screw in your compression tester, make sure on zero, open throttle (most people forget this) and crank over once through 3/4 cycles. That's about it. Write down the results. Any low results can be diagnosed by squirting a small amount of oil down the plug hole - if that helps the result then maybe piston rings are worn. If you have two adjacent cylinders down then possible gasket blown between the two cylinders. Quote Link to comment Share on other sites More sharing options...
Pete Posted October 28, 2005 Share Posted October 28, 2005 This link is more thorough in it's description http://www.georgiazclub.com/tips/ztech/comptest.htm Quote Link to comment Share on other sites More sharing options...
JohnA Posted October 28, 2005 Share Posted October 28, 2005 C'mon guys, next thing we'll have a "How To" describing how to open the doors... Quote Link to comment Share on other sites More sharing options...
Alex Posted October 28, 2005 Share Posted October 28, 2005 C'mon guys, next thing we'll have a "How To" describing how to open the doors... I've never done a compression test and THANKS to Pete I at least now know what's involved before I've gotten my hands dirty... Quote Link to comment Share on other sites More sharing options...
Pete Posted October 28, 2005 Share Posted October 28, 2005 We all gotta start somewhere John me old expert! Quote Link to comment Share on other sites More sharing options...
Tom Posted October 28, 2005 Author Share Posted October 28, 2005 I honestly didn't know it was gonna be this easy!, I just remembed seeing some guide somwhere and there were gauges and things all over the place! maybe it was something different! anyway i'll be back later to post results. Quote Link to comment Share on other sites More sharing options...
dangerous brain Posted October 28, 2005 Share Posted October 28, 2005 Don't forget to turn off the spark he he Quote Link to comment Share on other sites More sharing options...
eyefi Posted October 28, 2005 Share Posted October 28, 2005 it's the fuel you want to turn off, you don't want to be squirting fuel into the cyl while trying to measure compression. it's not goint to be doing much sparking unless you plug in the coils and then put the plugs in the coils. pull efi1 & 2 fuses. Quote Link to comment Share on other sites More sharing options...
Tom Posted October 28, 2005 Author Share Posted October 28, 2005 (edited) .,,,,,,,,, Edited February 25, 2009 by Tom (see edit history) Quote Link to comment Share on other sites More sharing options...
Tom Posted October 28, 2005 Author Share Posted October 28, 2005 oh just to add that my battery was pretty much dead afterwards! and needs a replacement one if that makes any difference. Quote Link to comment Share on other sites More sharing options...
eyefi Posted October 28, 2005 Share Posted October 28, 2005 won't the battery recharge? compression testing usually shows up a poorly battery. did you do the same amount of crank revolutions for each cyl? throttle full open for every cyl? because you haven't stopped the injectors spraying you are washing the oil seal off with petrol. so while you where testing no1 cyls 2-3-4-5-6 where receiving petrol (reducing your compression), then when you where testing no2 cyls 1-3-4-5-6 where still getting more petrol. so on and so forth until you come round to test no1 again which has seen quite alot of fuel by now since the first test. hot and cold engines will provide different results also. Quote Link to comment Share on other sites More sharing options...
Tom Posted October 28, 2005 Author Share Posted October 28, 2005 ahhh, ok, i'll try again tommorow if I have time with the fuses pulled, or i'll get phoenix to do it! same amount of cranks each time too, thing is the car is lovely and smooth, the test was due to curiosity! Quote Link to comment Share on other sites More sharing options...
Tom Posted October 28, 2005 Author Share Posted October 28, 2005 also to add,that I searched on here about compressions tests too and someone mentioned that all the plugs should be pulled? is that correct? Quote Link to comment Share on other sites More sharing options...
Pete Posted October 28, 2005 Share Posted October 28, 2005 also to add,that I searched on here about compressions tests too and someone mentioned that all the plugs should be pulled? is that correct? Don't think so. I've always done one at a time. Thinking about it I'm not sure it'd make much difference. You could argue that the other pistons will have less resistance/compression making the crank easier to turn over maybe? Quote Link to comment Share on other sites More sharing options...
Alex Posted October 28, 2005 Share Posted October 28, 2005 This test should be done on a HOT engine. So to clarify; Hot Engine Fuel Pump unplugged 1 plug at a time removed.. Working battery A flooded engine won't start but give it time and it will again... Quote Link to comment Share on other sites More sharing options...
Miguel Posted October 28, 2005 Share Posted October 28, 2005 Hmm interesting . Can i ask why there is a reason why all the plugs should stay in and only be done one at a time . I have ALWAYS done it with all the plugs removed. Here is a little linky walkthrough. http://www.pumaracing.co.uk/comp.htm Also has a guide for leak down testing also ...far easier than me typing it in my bad english. Oh and this has been covered before http://www.mkivsupra.net/vbb/showthread.php?t=45597&highlight=compression+test Quote Link to comment Share on other sites More sharing options...
Terminator Posted October 28, 2005 Share Posted October 28, 2005 Me too Mig, all out!! Why kill the battery with all that unecessary compression. Much quicker too and therefore engine temps are likely to be nearly the same from first to last. Quote Link to comment Share on other sites More sharing options...
Miguel Posted October 28, 2005 Share Posted October 28, 2005 Not only that Termy ..but with all the plugs removed the cyls that are being tested can pull the max amount of air from the plenumb while the others are venting from the spark plugs hole ...therefore making sure that the maximum volume of air is going into the tested cyl and not being shared making for a quicker test, which means less stress on the battery and less time for dry cranking to cause damage. Quote Link to comment Share on other sites More sharing options...
eyefi Posted October 28, 2005 Share Posted October 28, 2005 if you crank with the plug out it will blow and suck from the plug hole, chance of some nasty foreign object to be sucked into the chamber. it takes me about 20 seconds to remove a plug, so after the extra 2 mins taken between doing the no1 and no6 i dont think my engine has changed temp enough to warrant any real concern over the effects that would have on the final figures. Quote Link to comment Share on other sites More sharing options...
JohnA Posted October 28, 2005 Share Posted October 28, 2005 if you crank with the plug out it will blow and suck from the plug hole, chance of some nasty foreign object to be sucked into the chamber.. ah, but don't you always blow compressed air around the plugs before getting them out? Basic precaution, isn't it? Quote Link to comment Share on other sites More sharing options...
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