Larry
I agree with the philosophy that the foam will not transmit heat and give a false reading. but the tubing is downstream of the sensor. I think they used the foam for remove and replace ability. Even though you have to glue the foam piece. It may be easier to work with when going through the glove box to replace it. I 'm not sure. The photo below shows the entire tube assembly. does that section go by the heater core and is subject to heat? If so would it really make a difference in the sensor reading? Or did they anticipate that the hose would deteriorate at this location due to the heater core location? I really don't know and I'm grasping at straws here. So The car will now have the plastic tube and in 10 years I'll find out why they did this. I'll probably have to take the dash out again to replace the tubing instead of just doing it throught the glove box.

Dave

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1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car