[987kmns]

Here's a little DIY on replacing the coolant temperature sensor and the thermostat on a 996 GT3. Hope someone finds this useful. The job is not as much hard as it is wet.

Start by opening the trunk...hood...engine cover thingy. Inside you'll find the airbox (and engine - hopefully). This needs to be removed, so undo the hose clamp, unclip the MAF sensor, and remove the 13mm bolt securing to airbox to the body.


Next, remove the junction box support. There are 2 nuts securing the junction box to the support bracket and 3 bolts securing the support bracket to the engine.


Here is the junction box support bracket removed.


The engine bay with airbox and junction box support bracket removed.


Next, locate the coolant temperature sensor. It is right behind the alternator.


Remove the harness connector and move it out of the way. The photo shows the electrical connector already removed.


You are now ready to remove the coolant temperature sensor, but if you want to minimize the mess, I would suggest draining the coolant. In my case, I was also going to replace the thermostat, so draining the coolant was a must. Jack up the rear of the car and locate the two coolant drain plugs.


Place two large buckets to collect the coolant and open the drain plugs using a 5mm hex socket. I also opened the cap on the expansion tank to allow the coolant to drain better.


Time to remove the coolant temperature sensor. I noticed that an O2 sensor socket works best as it is split down the side, allowing it to fit over the sensor and plastic connector.


View with the sensor removed.


Comparing the old and new sensor. Identical. Install the new sensor and you are done.

[987kmns]

Next, I moved on to the thermostat. Locate the thermostat - it is at the front of the alternator and down to the left. Pull of the clip securing the coolant hose to the thermostat housing and separate the hose. Picture shows clip already removed.



Use a syringe, baster, or rag to get rid of the coolant in the thermostat housing.


Now, remove the three bolts securing the camshaft end cover to the cylinder head and remove the cover. Gently pry the cover off with a screwdriver. This will allow access to the third (lower) bolt on the thermostat housing.



With the camshaft end cover removed, it is time to remove the 3 bolts securing the thermostat housing to the engine. Arrows point at location of bolts. Third bolt is found at the bottom of the housing. You can now pull the thermostat housing off the engine. Make sure to also retrieve the metal gasket.



Here is what the thermostat looks like.


Use a socket large enough to go over the head of the thermostat to compress the spring and rotate the thermostat out of the housing.


Install the new thermostat in the housing, clean the gasket material off the housing and engine, and reinstall the thermostat housing. That's it! The last step is to fill the car up with coolant. If you captured the old coolant in clean buckets and would like to reuse it, that's OK too. I used a fine paint filter to pour the coolant back into the expansion tank. The cooling system will now need to be bled. There are many way to achieve this. The articles section on Pelican has great guidance on the process.

Enjoy!

[N0tt0N]

Nice! and Pretty! Carmon Red is THE color!

[BlackTalon]

Another great DIY write-up. You battling Martin for most HOF posts?

[Jazzbass]

Originally Posted by BlackTalon

Another great DIY write-up.

No kidding. Great stuff, Mihnea - thanks for posting.

[BillC]

Excellent article!

A question about the camshaft end cover: do you need a new gasket once you remove it? Or does it go on bare, with no gasket or sealant?

[987kmns]

Thank you guys for all the positive comments! I love writing these little DIYs up every now and then, hoping that someone will find them useful. So far, I think the Cayenne ones I wrote up have been the most popular.

[987kmns]

Originally Posted by BillC

Excellent article!

A question about the camshaft end cover: do you need a new gasket once you remove it? Or does it go on bare, with no gasket or sealant?

The cover does have an o-ring on the perimeter. It's in the plane that is perpendicular to the face of the cover, if that makes sense, so it goes into the block. On M96 and M97 engines, the equivalent cover has an o-ring in the same plane as the face of the cover, so the o-ring is more prone to leaking in that scenario. In this case, I didn't have a spare o-ring for the cover, so I went ahead and reused the original, which seemed reasonably perky still. I lubed the o-ring with some engine oil to make sure it would slide in and not get pinched. If it starts to leak, it's easy enough to pull the cover off to replace the o-ring. Fingers crossed for now.

[Casey914]

I have never seen a Carmona Red GT3. I remember when I worked at a dealership in college, the only 2004 turbo cab they received was in that color. Very cool.

[987kmns]

Originally Posted by Casey914

I have never seen a Carmona Red GT3. I remember when I worked at a dealership in college, the only 2004 turbo cab they received was in that color. Very cool.

Me neither, until this one. Apparently 1 of 15 in Carmon/Carmona Red and 1 of 1 in Carmon Red with a natural brown, full leather interior.