Overheating and No Heater
 

Hi guys please help! My 1998 Porsche Boxster auto trans 134k miles. It started when the dash tachometer and speedometer acting up and suddenly stop working only thing working is the water temp and the gas (car still drives fine) after 20 mins of driving the car got overheated so I pulled over and saw coolant leaking. I got the car towed and inspected the car the next day. I found out the reason why It got overheated because the serpentine belt retracted due to one of the idler pulley gave up. Thank God no oil and coolant mixture but the coolant reservoir got cracked hence it was leaking when It got overheated. I ordered the parts right away (coolant reservoir, serpentine belt, idler pulley) and installed them. I started the car and starts right up but the tach and speedo still not working (disconnected the tach and connected back and checked the fuse and all looks good) but still not working. After 20 mins of idle car temp is still fine but when I turned on the Heater no hot air coming out (AC works fine). I took the car for a short drive then I noticed temp goes up to 200 so I went back home immediately. Check engine light is on so I scanned it and shows P0117 (Engine coolant temperature sensor 1 Circuit low) So I bought a coolant temperature sensor and replaced them right away (part no. 99660640501). Started the car and it's same thing got temp goes up after 20-30 mins of idle. I'm thinking to replace water pump and thermostat but any tips with this issue is highly appreciated. Thanks!

Sounds like there is air in the coolant system. Before replacing the water pump or t-stat, I'd bleed the coolant system again to make sure that its not just an air bubble.

To expel the air bubbles.....
1) Open up the pressure relief valve under the coolant fill cap plastic cover (a chromed D shaped toggle ring) - lift it into the vertical position.
2) Top up the coolant to the max line.
3) Drive the car for at least 20 minutes to completely open the thermostat. Let it cool completely - several hours.
4) Repeat heating / cooling cycle 3-4 time with the D ring still open, Check coolant level after each cool down as you will probably see the level drop as air is expelled out of the system.
5) Reposition the D ring when coolant level stabilises.

Cool will try this. Thanks!

The problem with the instruments may be the infamous ignition switch ?
Refilling these is tedious to do w/o problems.Neilb has a recent video to help you if you Search/ask.

Raising the rear of the car a bit can help air migrate towards the tank.

If it's full and no heat, that would point to a bad thermostat not opening up and allowing the water to fully circulate.

Problem solved! followed the coolant bleeding instruction and it worked, heater is back too! Thanks a lot guys it saved me of buying water pump and thermostat. Now, move on the the dash problem ;)