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Old 03-11-2001, 07:35 PM
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Join Date: Apr 2000
Location: Falls Church, VA
Posts: 5,315
This is one of those situations that makes me sad. I wish I had a farm with a giant barn with space for all these orphans ...

Last week I closed a deal on a rust-free '73 280C with a siezed engine. It is now on its way from Arizona on a trailer. Today I looked at a '73 280 which supposedly had a good engine.

Actually a better car than expected: all there, good chrome and glass, new floors, good interior parts. Engine complete and original. Not greasy, newer carb, new plug wires, cap, etc. Oil on dipstick looked OK.

Fired it up and the engine seemed to miss and exhaust smelled rich. Oil pressure good. Blow-by not excessive. Pulled plugs and all were sooty. #5 was wet with oil and obviously not firing. Checked compression and it was 110-120.

Question. Is the low compression and #5 problem likely to be valves and seals, in which case I would consider making a low-ball ($200) offer? Or is it likely to involve rings, in which case I walk?

Thanks in advance for opinions.

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Old 03-11-2001, 11:40 PM
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Join Date: Dec 2000
Location: Battle Ground, WA
Posts: 576
110 oil problem....

Hi there,

When we got our '74 280C it was using great quantities of oil and would foul the #1 plug quite often. I finally noticed that the vacuum line going into the vacuum pump was clean but the one going from the pump to the intake manifold was very oily. That's right, the vacuum pump had a hole in the diaghram, and every time we went down a hill it would load up with oil and smoke like crazy. What I did was just remove the pump, it's not necessary anyway, and M-B got smart and removed it on the later year vehicles also. You might check your engine and just see where the line from the vacuum pump is plumbed into the intake manifold.... assuming it has a vacuum pump to begin with. Otherwise, I would suspect valve stem seals first, then rings. You can check the rings by doing a compression check. Worn valve stem seals usually cause an engine to smoke when it's first started after sitting for awhile.
Good luck with it, they are nice driving cars...

Richard Wooldridge
'82 300D/4.3L V6
'74 280C
'77 Jag XJ6L
'77 280Z
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Old 03-12-2001, 06:14 PM
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Join Date: Dec 2000
Location: Mt. Airy, Maryland
Posts: 116
As Richard suggested do a compression check. When checking the #6 cylinder pour about 1 or 2 table spoon of oil in. If the compression improves its the rings if it dose not than its the guides and seals.
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