Ruck Posted November 30, 2011 Report Share Posted November 30, 2011 My sweet '83 King Cab needs an engine and although I could find a used one (been there, done that, sad story) I am seriously considering a rebuild of one of the spares I have in the garage. I want the equivalent of a factory rebuild that will last at least 50-75K miles. Is there already something in this forum I've missed titled 'Top ten things for a moderately mechanically inclined person to consider before rebuilding your engine'? Quote Link to comment
datzenmike Posted November 30, 2011 Report Share Posted November 30, 2011 Sometimes the wear is so slight that you can simply re-hone the cylinders and install new rings. Only way to know is to have them measured and compare to the piston width. And no, the 89mm Z24 bore is not 89mm and neither are the pistons. Close but all fall within several ranges or tolerance because they are mass produced. Careful measuring will tell you if you need to over bore and get over size pistons and rings with closer fit. If over boring, the cylinders have to be bored to match the pistons so they must be supplied to the person doing the work. An 89.5mm piston may not be exactly 89.5. Could be slightly over or under so the bore must match it exactly for proper fit/clearance. Quote Link to comment
Ruck Posted December 2, 2011 Author Report Share Posted December 2, 2011 Thanks. For an older engine (250K+ miles) I should assume the wear needs to be measured. Can this be done without removing the pistons? How about the crank? Quote Link to comment
datzenmike Posted December 2, 2011 Report Share Posted December 2, 2011 Well you can measure the bore with the piston a BDC. Rod and main journals can be measured by using Plasti-Gauge. If rebuilding it, it can be measures when taken apart. 1/4 million miles can safely be taken for granted that it can be re-built. Quote Link to comment
ggzilla Posted December 2, 2011 Report Share Posted December 2, 2011 Yep, probably at most needs new rings and timing chain set. The bearings last usually at least 1/4 million miles. You can measure ring wear without taking the engine out. Do the smoke-throttle tests and a compression test. Don't fix what ain't broke. The Z-series engine is a tough engine. Quote Link to comment
Ruck Posted March 4, 2012 Author Report Share Posted March 4, 2012 Appreciated. I'm now driving this thing back and forth to Starbucks. It blows blue smoke on acceleration. I'm going to do a compression test. Any way to diagnose bad valve seals (versus worn rings)? Valve seals are relatively easy to replace and I guess I could just replace them and see whether that makes a difference. Quote Link to comment
Ruck Posted March 4, 2012 Author Report Share Posted March 4, 2012 I was searching and found this link, answering my own question. Apparently no difference between a wet and dry compression test will point upwards to the valves. http://datsun1200.com/modules/mediawiki/index.php?title=Compression_Test Quote Link to comment
Ruck Posted March 4, 2012 Author Report Share Posted March 4, 2012 And this link: http://datsun1200.com/modules/mediawiki/index.php?title=Smoke Quote Link to comment
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