You mentioned not finding oil in the radiator. What about the oil? Is there water in it? Once the gasket really blows, your motor oil will be something similar to the color of a chocolate milk shake - more a lightish brown color.

I would consider the following first:

a. thermostat
b. coolant - is there a sufficient amount and is it clean?
c. water pump operating properly
d. Radiator - how old is it? The do wear out and clog up with age.
e. fan clutch

There are all sorts of ways to test for a blown head gasket. It's my belief that's once they're "BLOWN", it's a no brainer. You get the milk shake I mentioned above.

There's also such a thing as a "LEAKING" head gasket. That's one that has not yet "BLOWN". Some symptoms of that include:

a. engine doesn't seem to want to idle on it's own when started up cold first thing in the morning. You have to idle it at a higher rpm for several mins. before it will idle. This is because when a head gasket is leaking, you're losing pressure.
b. Once underway, you'll notice the temp. gauge wandering a bit. You'll see the needle going into a higher area, staying there a bit, then dropping back down.

These are but a few things to look at. Use the search facility here to check for other ideas.

I would not at this time assume you have a head gasket issue just because you're running warm.

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"