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New Engine with Compression and Oil Issues

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Offline JCTracker

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New Engine with Compression and Oil Issues
« Reply #1 on: January 03, 2019, 08:32:14 AM »
Happy New Year everyone,

I've recently reassembled and installed a 1992 1600 8V engine. I had a local machine shop do their thing to the head, block and crank (.02 bore, new valve guides, 3 angle seats, crank just needed to be polished etc). I also replaced the rockers and rocker shafts to go along with the new 272 cam I got from Low Range Offroad.

Using a Top Line Automotive rebuild kit (all gaskets, pistons, bearings etc) I  assembled the engine following the 9 videos covering assembly of a 1300 engine over at on Low Range Offroad's You Tube site.

After running the new engine for about 100 miles to let things wear in and rings to seal I ran a cold compression test on the engine and got 150 PSI dry and 175 PSI wet on all cylinders with WOT. I was a little disappointed in those numbers as the 28 year old engine I pulled out with at least 165K miles on it gave up 165PSI cold but I was more concerned with the amount of oil I was seeing come out of the tail pipe.

After another 100 miles I drained the oil which was super black and down 1.5 quarts. Worried there might be an issue inside I decided to pull the engine, open it up and check things out.

I found all of the rings were OK and properly installed and staggered. Bores still looked good with no signs of scoring. Bearings looked good everything else (i.e. wrist ping clips, oil pick-up etc) were still in place. Nothing on the end of the magnet I swirled through the used oil except for minor, dust sized metal which I expect during break-in.

I checked the end gap of the two compression rings in all cylinders and got consistent .024 for the top ring and .016 for the second. According to my manual and what I've seen online and factoring in the .20 over pistons I think these numbers should be .009-.014  for both. I contacted tech support over at Top Line and was told they think the ring gaps measurements I'm getting (.016 and .024) sound right.

So I'm stumped. To address the oil consumption I've ordered another set of rings hoping that I'll get different numbers and plan on replacing the valve stem seals just because I have a set and I might as well. The guys at Low Range recommended changing the valve lash to .008 and .010 (cold) which I hope will bring the compression up after I get everything back together.

Other than that I don't know what else to check or do and was hoping to post my saga here for some feedback and any suggestions. What do you think? Do the Top Line ring end gaps sound right to you? What about the compression test results? Just right or on the low side? Anything jump out at you that I might have missed? Anything info I might have left out that could help you help me?

Thanks in advance for any help
1990 Geo Tracker Tin Top, 4x4, 5spd (Mine)
1992 Geo Tracker Soft Top, 4x4, 5spd (Hers)
1995 Geo Tracker Soft Top, 2WD, Auto (Fixer up'er)
1995 Geo Tracker Soft Top, 2WD, Auto (Parts for above)