The cooling system is the most important part to keep up to snuff. Nothing else really matters, if the head is going to crack, it's going to crack. Whether or not those cracks lead to compression leaks or oil/coolant consumption is luck of the draw. I personally think the paranoia behind the 14 head is overblown.

The hunting temps are probably due to thermostat problems or fan clutch as you mentioned. Mine hunted would drift up to 100-105 in hot weather with A/C or slow traffic until I changed the fan clutch. Swap over to the 606 turbo clutch and 11 blade fan, it helps the A/C and helps airflow over the radiator.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

X2

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.