More cooling issues + Q ...

[BodhiBenz1987]

... as though we need another thread on this topic. Temps were 105F outside today, and going up the mountain my car went above 110, looked like about 115 ... scared the p*ss out of me (well, not really, because I was so dehydrated that would be physically impossible). I did not hear the aux fan come on. If the hill/mountain hadn't ended, I'm sure it would have overheated (I would obviously pull over before it reached that, but in theory). Once over the mountain, on the downhill, the temps went all the way down to low 80s. I'm not sure what else to do at this point, as I've cleaned out the rad, replaced the tstat and replaced the clutch ... I guess fixing the elect fan would be a start, because that does not seem to kick in. Not asking advice necessarily since I know I have run this topic into the ground, but I do have two questions:
1) What does the aux fan sound like? Shouldn't it be roaring loud? Just want to make sure it didn't come on and I missed it ... there wasn't that much traffic, so I could hear my car's noises, and it didn't make fan-like sounds. I would think that the initiation of the aux fan would be accompanied by a stop to the temperature rise, too, whereas mine seemed to keep going up without slowing at any point.
2) Where is the sensor that provides information for the instrument-cluster temp readout? Does it read from the radiator or back on the engine? Are there different sensors for 1) the clutch fan, 2) the elect fan and 3) the dashboard readout? Just wondering if it's possible my readout is wacky and the system is actually working fine. I'm going to take it in and have my indy shoot it with the temp gun to check, but I'm just wondering the sciences involved here.

It's a stinker out here ... right now it's about 105 degrees and humid. I'm sure you guys from Arizona and Texas aren't impressed by that, but we aren't used to it in Pa. and Del., which is where I was driving today. I can't remember a time it was this hot out. So I'm burning up and so is my car ... I guess if I didn't have so many things to worry about, I wouldn't know what to do with myself...

[turbodiesel]

You flushed the coolant system, replaced the thermostat and fan clutch by yourself? Impressive! Not a small job. Did you fill it 50/50 with MB or Zerex antifreeze and water?

The electric fans should come on automatically as soon as you turn on the A/C. If not there is a problem. I think your 603 engine reads the temp from a sensor on the thermostat housing.

[BodhiBenz1987]

Originally Posted by turbodiesel

You flushed the coolant system, replaced the thermostat and fan clutch by yourself? Impressive! Not a small job. Did you fill it 50/50 with MB or Zerex antifreeze and water?

The electric fans should come on automatically as soon as you turn on the A/C. If not there is a problem. I think your 603 engine reads the temp from a sensor on the thermostat housing.

I should have said I had my mechanic do those things. I did hose out the radiator ... whoo hoo! I was set to try the t-stat swap, as that looked within my scope, but had no lift or jackstands, and decided I didn't really want an anti-freeze facial. I wish I could say I did all of it myself, but I don't have the knowledge yet, or the facilities/tools to do a good job. i can only hope that as I get more "settled" in my life, I can begin to do some nifty stuff like that.

I believe it is running 50/50 MB but would have to doublecheck ... I assumed that is what my indy would use and didn't think to ask.

This car does not have the A/C compressor hooked up, so the aux fan never runs ... this is the first time the temp on the dash readout has ever reached 110 or more, so the aux fan issue has never really come up. At this point then I guess it makes sense to get it checked out, although I plan on avoiding that mountain as much as possible (which makes me sad, because I really enjoy road trips in the Benz )