speeder Posted March 7, 2003 Share Posted March 7, 2003 I posted this in the troubleshooting board first, but looks like not too many peoply go there... While performing a leakdown test on an L28, I tested each cylinder at TDC, and got horrible (20-90%!) readings. I know that the engine is not that bad. Then, with the leakdown guage connected, I then turned the engine CW a short distance through TDC so that the applied air pressure just began to push the piston down. At this point, evry cylinder indicated less than 5% leakdown. I'm sure of my TDC position determination throughout this testing. 2 questions: 1. WTF!? What causes this phenomena? 2. Is this engine good? Thanks guys. Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted March 7, 2003 Share Posted March 7, 2003 If the lower edge of the ring lands are damaged, maybe the ring seals it when it begins the downward stroke Can you tell whether the air is leaking into the crackcase (check the breather holes or dipstick hole) or from the valves? (check for air out the intake or exhaust) Quote Link to comment Share on other sites More sharing options...
speeder Posted March 7, 2003 Author Share Posted March 7, 2003 Air is definitely leaking past the rings to the crankcase. When moving the rotational position, after each piston got past the "bad" point (TDC), the reading didn't change whether I moved the piston up or down. I also was thinking ring land damage, bot wouldn't that give the same leakeage at all points in the stroke? I suppose I'll take this engine apart and take a look. Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted March 7, 2003 Share Posted March 7, 2003 Rick, if it is the one I gave you, don't worry about it. Just check out your old engine and go from there. Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted March 7, 2003 Share Posted March 7, 2003 I wonder if the rings or the ring lands have been worn enough to not give a proper seal when the rings are not pressed up or down against the lands (i.e. tdc) either way, you should redo the forged internal engine anyway, or build that stroker you want Quote Link to comment Share on other sites More sharing options...
speeder Posted March 7, 2003 Author Share Posted March 7, 2003 Mike, I was just trying to evaluate the prospect of getting the head sealing fixed and driving on the engine that's in there. I don't feel good enough about the loaner engine to do that, so I'll just pull it out and fix the forged motor. I still intend to solve this mystery, however. Will definitely look at those pistons for educational purposes. Yes, I'm starting to look for anLD28 Crank - If I need new pistons in the old engine it's stroker time for me. Quote Link to comment Share on other sites More sharing options...
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