L28ET WEIRD COMPRESSION

[J240ZTurbo]

Hi guys, well I got a nice low miles 280zxt auto few weeks ago and started playing with, the previous owner told me that it sat for a long time, I put some oil on the cylinders before firing her up, and she did for a minute or two with lots of back firing do to old gas, so I decide to take some of the old stuff to the trash and, got my self some new plugs, filter , a nice fuel rail ect, from here I notice that some of the old injectors where not firing up, so I got new injector. So here is the question , today after a month I decide let me do a compression test on this girl , all cylinders came up to 150-155 with no problem exept for #6 this one came up to 120 . I can tell she sat for a very long time, but does anyone know why this is happening will it fixed by itself once she goes on the road?

 

Please help worry here!

Juan

Edited January 25, 2012 by J240ZTurbo

[destruck]

Have you tried putting a cap or two of oil in the spark plug on #6 and re doing the test? Possible the rings are leaking. Generally speaking, I don't think motors "fix themselves", usually tend to get worse over time / use.

 

You could also try a leak down test to see where your losing the compression if the oil doesn't make it go back up.

Edited January 25, 2012 by destruck

[dexter72]

Have you performed a valve adjustment Yet?. I recommend doing that first and make sure everything looks good on that cylinder, valve springs, valves not sticking, Camshaft lobes. After doing the adjustment check compression in that cylinder again. If you have no compression change, I would add some oil to that cylinder. If oil raises the compression number, then the rings or possibly cylinder is the problem. If the compression number stays the same after adding oil, then you have a problem in the cylinder head, valve, or guide.

 

Keep us posted.