My '87 300 SDL has been starting harder the last few weeks. Runs rough for 30 secs, more smoke, etc. Very strange as it did this all winter, but cycling the glow plugs twice usually took care if it even when temps were in single digits. Now if I cycle twice, it is still rough.

New glow plugs were installed in December.

Once it settles, all it well, runs great.

Help?

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Alan Hamm
'87 300SDL 277K Miles
'89 560 SL 68K Miles

It could just be bad GPs. If only a couple go bad the car will still start sometimes but it will be rough when it does. I'd take a tester to the GPs to check them again.

Even at 60 degrees I find that my cars hate to start without some glowing. They wil start eventually but man what a mess of smoke and rough running for the first thirty seconds.

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

Just because the glow plugs are reasonably new doesn't guarantee that they are good, test them again. I agree with Fisherman, sounds like a bad plug or two.

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1985 300D Turbo ~225k
2000 F350 (Powerstroke) 4X4, SWB, CC, SRW, 6spd ~148k
1999 International 4900, DT466e (250hp/660 ft/lbs), Allison MD3060 ~73k