drb007

My thermostat on my 90 C4 looks exactly like the one you have pictured, and I just replaced the element. I used a thin bladed screwdriver and a needle nosed pliers to remove/destroy the old circlip. I couldn't get the screw next to the element opening out on my car either, but I carefully tapped a small punch along the edges of the plug and it popped out. Maybe I am really lucky?
Once I had it out, I put in the new element and o ring. Advice...put the new plug (or old one if you haven't drilled it) back on using a vice to compress the oring.
Total time less than 2 hours and I was not rushing.

Jeremy Pinsly

I had a similar problem in my 90 C2 Cab.......Temp gauge went to the 10:00 position with normal driving. Suspected bad thermostat...Sure enough it was. The sticking thermostat was replaced with a thermostat insert (964-207-349-02), rubber hoses (964-207-241-06 and 964-207-251-03) and an o-ring (999-707-393-40) and I was back in business.

Johnny G Pipe

Umm..What is the screw next to the element opening for?

DarrylH

I have a very early build '90, no removable element, hence the full replacement. Dunno about 03 vs 08, 08 is what I got, maybe that's just all that was available? Maybe you'll get lucky and won't need one. Since yours can be dismantled I'd sure give it a try. They seem to be fundamentally pretty simple devices...

Arrivare

The socket head screw is to hold in a spring and ball that act as a pressure relief device. It is worth taking these out and giving them a clean if you dismantle the rest.
On my car I have repaired the corrosion on the right hand side by welding in a repair section using a template made from the original underseal that had been left in position as the metal corroded away! I have yet to do the other side where the damage is more extensive.
In answer to your comment about the pink carpet, it is the one in my garage. Is a carpet in the garage not a requirement for Porsche ownership?
Allen

Jerry Garwick

Thoughts on this issue. The circlip is most easily removed with circlip pliers. I have several sizes of pliers purchased from Harbor Freight here in the US. I don't know if the store is in the UK but the pliers are common. The circlip pliers are very useful in your tool kit.

As for the cover, IF it is steel, I would try to use a stud gun to get it out if stuck. The stud, when welded to the plate, could most assuredly be removed with the puller-hammer. Having said that, I've recently worked on my thermostat and cannot tell if the plate is steel or aluminum.

c2dweller

After breaking the end of a pair of circlip pliers I borrowed I found it easier to put use a pair of long nose pliers. I'd do one side of the circlip at a time and gently tap it out with a hammer - hitting the plier jaws.

c2dweller

... and also - to remove the cap I did the screw thing, however it wouldn't budge for me. I found using a claw hammer, hooked under the screw head, provided just enough leverage to remove it!