d4 thermostat and idler bellows seals

hi guys,
just wondering at what temp should the thermostat begin to open in a D4.
i bought a new one some time ago which has a detroit logo on it, but dropped it on the carpet as I was pulling it out of the packaging, so i thought i better test it first.
it opens up at 94 degrees Celcius or 200 farenheit.
seems a bit high to me, considering by that time there are steam bubbles forming round the saucepan.
i used an infrared thermometer and pointed it to the fluid resovior end of the thermostat.

the other question relates to the bellows seals (7B563😎 for the front idlers.
the cheapest i have found is 44 bucks each from florin, does anyone have any cheaper sources or do i just quit my yappping
and fork over the hard earned.

thanks.

http://www.machinerytrader.com/list/PartsSearch.aspx?PartNum=7B5638

http://www.rockanddirt.com/parts-for-sale/CATERPILLAR/7B5638