Compression Test, How Do I?

[rico05]

How does one do this with the engine out of the car? Just realized that I never did that to my motor. Place I bought it from said it came from a running car, and had low miles, but I am still nervous. Thanks.

[Fla S13]

get a car battery and sum heavy gauge wire hook one to the(-) on the battery and to the starter ,and then hook another wire to the positive on the battery then tocuch the (+) prong on the starter...

DJ

[pulsar gtr]

Well, I highly recomend doing a leak down test on the engine instead of the compression, leak down test is more accurite and it gives you more info on the internals of your engine compare to the compression test, plus the compression should be done when the engine is warm where it should be running for 10-15 mins in order to get the rings to expand a bit , this way you will get the best reading, and since your enigne is not installed , you can't get it warmed up.Also, I recomend before doing the test on it, to put some WD-40 through the spark plug whole and turn th engine few times to get the cylinder walls and the rings the proper lubrication in order to achieve the proper measurements.

PULSAR GTR

[rico05]

Great! SO who wants to tell me how to do a leak down test?

[pulsar gtr]

ok, you get the leak down gauge, and your remove all your sparkplugs out, get some WD-40 and put some on the top fo the pistons, turn the engine about 3-5 turns, install the leak down gauge hose instead of the spark plug, now before you install the gauge into this hose, install the air pressure hose(from the air compressor) into the gauge and calibrate it, once the gauge is caliberated at zero, plug the other end of the gauge into the hose that is going into the spark plug hole.Get yourself a 27mm socket with a wrech and start turning the crank pully clock wise, and watch the gauge, you should feel the pressure building and the you should see the gauge needle moving towards the green space (green is very good, red is bad), if it makes it to the green, make sure it stays there for 3sec, to insure there is no leak. if there is a leak, you should be able to hear it either through the intake or exhaust or through the other spark plug holes.( if it makes it to the green, you engine is in a good conditon) if not, you have to listen to the leak and determine where it is leaking from. for example if it is leaking from the exhaust side, it is the exhaust valves, same with the intake, if it is leaking through all your other 3 sparkplug holes, your rings are worn out, etc....

I hope that helps. also when you buy a leak down gauge it should have instructions on how to use it.

Good luck,

PULSAR GTR

[rico05]

Well crap. I don't own or have access to an air compressor. I guess I will let Silvia Werks find out for me.

[nab911]

How much is a leak down gauge...

[biosehnsucht]

I need a new compressor too, someone jacked nearly all my airtools and my 25gal compressor a few months ago! GRRR!!

All I have left is my big set of impact sockets.. the compressor was actually my stepmom's, she wasn't using it lately (used to use it for working on her 5.0 back in the day, but what with the kids she hasn't had time for anything of the sort, all it was used for lately was inflating inflatable toys and floats and stuff)