Re: 1940 120 flat 8 #2 low compression

Posted by Owen_Dyneto On 2014/4/6 8:20:44

Low compression or no compression in #2? Remove the valve covers, run or turn over the engine on the starter and make sure that all the valves are moving up and down - it's possible one valve has frozen in an open position though if so you'd probably be hearing some ojection from the lifter. Also check for a broken spring. Next thing to do is to check the valve tappet adjustment and make sure both lifters have some (any) clearance; if either one has no clearance, adjust the tappet clearance (might as well do them all) and retest the compression. If you still have none or low, then you'll have to pull the cylinder head to find the cause. It wouldn't be at all uncommon for an engine of that era to require a valve job at 50,000 miles though typically when that's needed all cylinders will have some compression, not one with zero (you didn't give us any actual compression values - if you don't have them, then do a compression test). Whether a simple lapping of the seats, or machine refacing of the valves and seats and possible replacement of one or more valves and perhaps guides depends entirely on what you find when you diassemble.

Here's a primer on valve work that might be good reading for you:http://www.packardclub.org/forum/viewtopic.php?f=14&t=862