jacob80 Posted January 30, 2010 Share Posted January 30, 2010 Hey guys, Well I just put ANOTHER new head gasket on my L28ET which has been rebuild with the stock P90 head but we put the "improved valve stem seals" from Ford. I replaced the head gasket because I noticed oil was leaking down the side of the block a little bit, but nothing major. It was a Fel-Pro gasket but I just replaced that with a genuine Nissan L28ET gasket. Just to be sure, I took the head to the machine shop to ensure flatness. Not sure if this is even a factor, but I just compression tested the motor a week ago. Keep in mind I have not really run the motor (as we have a bad clutch) and this is a cold test. The tested results ranged from 120-115. I read somewhere that the FSM calls for 145 :/ Is this something to be concerned about? I know they're consistent, but are these numbers too low for this situation? Thanks guys! Quote Link to comment Share on other sites More sharing options...
FlatBlack Posted January 30, 2010 Share Posted January 30, 2010 115-120 is not low, you should be looking for consistency between cylinders. Were you looking at the N/A FSM or the Turbo FSM? I would assume the L28ET's numbers would be lower due to the compression. Quote Link to comment Share on other sites More sharing options...
Xnke Posted January 31, 2010 Share Posted January 31, 2010 Jacob80, My compression on a newly built, but not run-in motor was 90PSI. After letting it run for 20min at 2000RPM to break in the new cam, as directed by my cam grinder, compression jumped to 149PSI. I'm still not fully broken in, but it is an impressive difference between freshly built and 20 minutes of run-in. Quote Link to comment Share on other sites More sharing options...
jacob80 Posted January 31, 2010 Author Share Posted January 31, 2010 Okay, good to know. Thanks guys! Quote Link to comment Share on other sites More sharing options...
dhughes Posted February 25, 2010 Share Posted February 25, 2010 im looking at a l28et, but it doesnt run.. would doing a compression test be the best way to tell if the motor is in somewhat good condition. im guessing from previous post it should be above 115.... thanks, sorry for stealing your post for a second lol Quote Link to comment Share on other sites More sharing options...
Daeron Posted February 26, 2010 Share Posted February 26, 2010 If you are investigating a junkyard/used engine for how good it might be, a compression test is not the way to go. It will do, and it is easy, but ideally you should run a leakdown test. Regardless how low the number is, if all six cylinders are pushing 85-90 PSI the engine will run fairly well, and surprise you with how much power it will have. If the same engine is rebuilt, run in, and re-tested to find 160 psi in all cylinders, it would not be a surprise. If, then, that engine somehow had one cylinder go to 130 while the rest were at 160, it would run like crap. If it ran. Compression checking has almost nothing to do with the absolute number; all that matters is the six cylinders show up within 10 percent of each other. Quote Link to comment Share on other sites More sharing options...
sbooth Posted May 14, 2010 Share Posted May 14, 2010 My .040 over zero deck flat top L28 w/ P90 also tests at 115-120 with the throttle plate NOT OPEN. Cam specs matter too. Quote Link to comment Share on other sites More sharing options...
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