93till Posted July 16, 2009 Share Posted July 16, 2009 So the motor me and my buddies pulled my 93 Lexus es300 not too long ago has approx 240K mi. I've been slowly tearing it down over the last few weeks. Once I got the intake manifold off I leak down tested it. Pressure was holding well... the leakage percentages ranged from 10-15%. In general, from what I've read, this tells me she's still got some life left. One thing though, there was air coming up and out of the intake ports. Did I do something wrong? I made sure each cylinder was at TDC when I tested them. Is the air coming from the intake ports supposed to happen? Quote Link to comment Share on other sites More sharing options...
George_Jetson Posted July 16, 2009 Share Posted July 16, 2009 As I am sure you are aware, when you run a leakdown test, you are pressurizing the cylinders. The air that you are getting from the intake ports is part of the 10% to 15% leakage that you see, this is air that is leaking past the intake valve. Now the next step would be to verify that the valve clearance is good because if you do not have sufficiant valve clearance, the valves will be held partially open and cause leakage. Of course this also applies to the exhaust valves, and if you remove the oil fill cap, you can listen for leakage into the crankcase (piston ring leakage). Quote Link to comment Share on other sites More sharing options...
93till Posted July 16, 2009 Author Share Posted July 16, 2009 As I am sure you are aware, when you run a leakdown test, you are pressurizing the cylinders. The air that you are getting from the intake ports is part of the 10% to 15% leakage that you see, this is air that is leaking past the intake valve. Now the next step would be to verify that the valve clearance is good because if you do not have sufficiant valve clearance, the valves will be held partially open and cause leakage. Of course this also applies to the exhaust valves, and if you remove the oil fill cap, you can listen for leakage into the crankcase (piston ring leakage). How is checking the valve clearance done exactly? Is it similar to honda's where a feeler guage is used and bolts are torqued down? Quote Link to comment Share on other sites More sharing options...
George_Jetson Posted July 16, 2009 Share Posted July 16, 2009 These engines use a replaceable shim, but otherwise the procedure is the same. Quote Link to comment Share on other sites More sharing options...
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