Thermostat Replacement
 

There is an Ebay posting for a 87 928 that said that the water pump has to be pulled to replace the thermostat. Looking at the part breakdown it appears that the thermostat is under a cap that connects to the bottom radiator hose. Looks like you remove the bolt, remove the thermostat and replace the O ring, thermostat and back gasket (what does this gasket do??) and you are done. Ok, someone who has done this, what is the catch? No split ring that you can't get ANY tool into like on the 951!!


<a href="http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=1828922761" target="_blank">Ebay posting</a>

928 descriptions on eBay are wrong more often than right, and that is true in this case.

You do not have to remove the water pump to change the thermostat. The 928 cannot be run without a thermostat - the back gasket seals the coolant passage when the thermostat is open. The thermostat is not "open or shut", it is more "block or radiator" - it circulates the coolant thru the block or thru the radiator. If you take the thermostat out and run the engine, you get very quick overheating.

Changing the thermostat isn't really a trivial task - it will take most owners from one to two hours - but it is well within the capabilities of a typical DIY owner.