Finally got around do performing my compression test. I have no idea what the car's history is before 240K miles, the valves were no where near adjusted correctly, uses a bit of oil (although not much at all if I keep the oil level closer to the lower mark on the dipstick it seems) and it won't start below 20 degrees so I was a little concerned. My results:
360
340
350
330
380
I'm not sure what range they should be in, but that has got to be pretty good for 260K miles. If nothing else, they are all almost within 10% of each other. I used the $30 Harbor Freight tester (worked great) on a warm engine (driven to operating temp in cold weather and sat for about an hour or so) and used the glow plug holes. It reached max. psi after 10 cranks (shot right up pretty quick too: about 100 psi per crank until it reached about 300 then slowly built up to max.)
Does anybody know the compression range when new?

first suspect is always glow plugs.

i hear a bit over 400 psi warm.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Are your results after setting valves? Compression range is around 350 and up, warm. Not bad with those miles. The 10% rule is pretty good.

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83 SD

84 CD

After. Adjusted them last year - drove almost 10K miles and adjusted them again not too long ago. My brother made the comment "too bad the 330 is right bext to the 380". I wonder what the lowest has to do with being adjacent to the highest?

The glow plugs seemed to test out okay. But I think I'll just replace them all now knowing that the compression is not an issue.

i can't see where they are matters.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Good for you checking after. An article in Star magazine suggestes a leak down test is a more acurate measure of engine condition. When taking compression test, note if gauge drops after cranking. Did on the '82. Yet, has no trouble starting, but VERY sluggish till warm. Will check banjo connections soon. Your test on GP's, with ohm meter? Have you checked voltage with plugs on? I checked the SD plugs, [ohm only] one was bad, replaced, no change, replaced all, still no change for single digit temp starts. Scratchin' my head on that one. One cylinder being low beside another, may mean rings vs gasket. Gasket eaiser, read cheaper to correct.

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83 SD

84 CD

Don't worry about compression or leak down tests. And don't change all the glow plugs just because. Make sure each glow plug meets the spec and make sure the voltage is getting to all of them.

Next in the list of cold starting tips is to make sure the battery is good and make sure the starter is good. Just because it turns doesn't mean a starter is good. When starters get old in these cars, they lose RPM and that can make all the difference in the world.

Another couple tips are to use synthetic oil and make sure the ground strap under the car is clean and tight (worth checking now if you haven't yet).

240Joe