My '98 S90 heated up really slowly once it got cold. I figured the thermostat was stuck open, so I ordered one and set out to replace it. Got one of those torx-head bolts off, barely, straining hard at the end of my ratchet handle. (I bought this car about 10K ago--it had been pretty badly mistreated.) The other one stripped out completely before I even came close to budging it--the threads were barely there to start with.

I worked on it for an hour or two, tried various vise grips and allen wrenches, then took it to my mechanic. He drilled out the bolt, and discovered there was _no_ thermostat inside the housing--just a ring like the one around a standard thermostats.

We got the car last spring, and so hadn't noticed that it wasn't warming up as fast as it should . . . it always heated up to 12:00 and stayed there, eventually.

Now, with the new thermostat, the gauge starts to rise in a minute or less, and in less than 5 minutes it's right at 12. Seems to stay right there, though I haven't driven it much.

I'm still trying to figure out what would have possessed somebody to open the housing up, take out the thermostat (broken or not) and then just stick that ring back in rather than replacing it. And then, on top of that, to tighten down those bolts with enough of a dying strain that they'd never come off again without a struggle . . .

At least there seems to have been no major damage done. Hoping for some trouble-free miles ahead!

Jeff