Originally Posted by sptt

After many months of replacing this and thinking it was that, I finally have my '91 300E starting like it was brand new ON THE FIRST TURN and catching on the initial crank like a NEWER car! Here is what I think has contributed to everyone's woes that I have repaired in mine:

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3. Flushed coolant and all the crud out. Put in Steel Seal ($80.00) with new coolant and ran in coolant per directions with heater on high for 60 min and let cool, etc.

4. Replaced all heater and radiator hoses and expansion tank as well as old thermostat that was corroded and stuck.

5. Installed proper 875 Amp Battery vs. the 610 Amp that PO had put in (what a spark and crank difference!!!)

6. Ran some more Liquid Head Gasket Sealant from BARS ($29.99 liquid stuff from Autozone that you can add to coolant and run for an hour with heater on high and then let cool overnight to seal any final cracks in block). This got rid of my smoke and the leaking coolant flooding into the cyclinders helping to create the hard starts! It works like promised and is still working and getting better by day.)