... after determining that there was no way on earth I could reach the tstat housing without any sort of lift, I took it to my indy to have it done yesterday. He put in the new t-stat and also replaced the sender on the engine. Now, this is the 300d so it had the blue one on it before (part#006545-6424) ... I understand there is also a gray one (for the sdl) ... the one he put in in GREEN and has the number 006545-4524. Where does this green switch come into the picture? I've never heard of a green one before ... it seems to have 105 and 115 (as opposed to 128) stamped on it, although I can't see that side well (it might be 125). My indy knows what he's doing, but I'm just curious about this sender.

On a side note, the car is running HOTTER than I thought it was ... the old sender was off. I drove it back to the central PA mountains today and it ran 90-100 the whole time (it had been running 80-100 according to the old guage). Dropped below 90 a couple times and once (on THE mountain, it went up to just over 100). It really hung at 90 most of the ride. It was about 85-90F ambient, so I'm not paniced about these running temps, but still concerned. I guess a coolant flush and radiator clean is in order, and for me is likely a monumental undertaking. Although my indy did not seem to think it was a concern, as long as the fan comes on when it should and it doesn't start hovvering up in the 105-120 range (which it hasn't).

The temps did read more consistant than before .. i.e. it was usually at 90 and did not fluctuate much, aside from going up closer to 100 when I went up a steep or lengthy incline. Once it hit 100 it would steadily drop back to 90.

__________________
1987 300D, arctic white/palomino--314,000 miles
1978 240D 4-speed, Euro Delivery, light ivory/bamboo--370,000 miles
2005 Jeep Liberty CRD Limited, light khaki/slate--140,000 miles
2018 Chevy Cruze diesel, 6-speed manual, satin steel metallic/kalahari--19,000 miles
1982 Peugeot 505 diesel, 4-speed manual, blue/blue, 130,000 miles
1995 S320, black/parchment--34,000 miles (Dad's car)

The temperatures that you describe are perfectly normal. The engine can easily climb up to 100°C. when under moderate to heavy boost. However, it probably won't reach 105°C. on any hills that you could possibly find on the east coast.

If it ever gets above 105°C., then write back.

It was getting pretty close on the big hill. I felt as though it would have kept going up had I kept climbing, but I reached the peak of the climb before the temp crept that far. Then again, this is as big a hill as I imagine I'll encounter ... unless I decide to roll backwards down it midway and go up it twice in a row. I guess as long as I avoid that, I won't have the concern.

Question on the side ... I notice that large trucks usually stop at the peak and rest for a while after the climb. I know they heat up A LOT, but wouldn't it expedite engine cooling if they kept moving down the hill after the climb? Or do they actually need to shut the engine off? Just curious about this.

__________________
1987 300D, arctic white/palomino--314,000 miles
1978 240D 4-speed, Euro Delivery, light ivory/bamboo--370,000 miles
2005 Jeep Liberty CRD Limited, light khaki/slate--140,000 miles
2018 Chevy Cruze diesel, 6-speed manual, satin steel metallic/kalahari--19,000 miles
1982 Peugeot 505 diesel, 4-speed manual, blue/blue, 130,000 miles
1995 S320, black/parchment--34,000 miles (Dad's car)

It's cooler up there for lunch.

Nice scenery, too??