I have a 1999 996 C2 with 61k miles. I have owned it since under 20k miles and maintain it meticulously. I havent driven it in a few weeks now (since the last speeding ticket) and moved it to sweep out the garage tonight. I drove it a couple miles and let it idle in my driveway while I cleaned the garage...just to recharge the battery. As I was sweeping, I look out and my car was overheating...it is about 30 degrees outside so I guess it looked worse than it was...but I ran out, cut the engine and popped the deck lid. It was bubbleing out of the overflow.

I let it cool down, added water...washed it down...and drove it about a mile and then back into the garage. I don't see anything leaking. I am not a DIY kinda guy. Is this normal if the car sits at idle for 15-20 mins? What could be wrong?

Also, I don't remember there being a spring inside the coolant resovoir cap...did this pop or is normal?

Thanks all...

 

sorry for what happened to your car. i have no idea what could have caused it.....but as far as being normal for letting it idle for 15-20 mins, i don't think that's considered normal. it's been very cold here in seattle as well. we start our 99 996 up and let it run for a good 20 mins every few days just to keep the battery going. we've not had any overheating problems by doing so. figure, you'd let it idle that much just sitting in traffic trying to get home sometimes. maybe if it was super hot outside, maybe?

anyway...best wishes and i hope all is okay with your 996.

 

No problem letting the car sit and idle. Possibly a stuck thermostat which might be a one time thing or pocket of air, bad cap or front fans not kicking on. Have you had any maintenence to the car recently? It is common to have problem with the cap. Cheap to replace.

 

Sorry to hear about your overheating. Did any warning lights come on? May want to check your front radiators for debris/blockage. I would suggest not to let these cars run/idle for extended periods of time, if you are worried about the battery, there are some good trickle chargers out there. The owners manual indicates that when starting the engine, "be ready to drive immediately". Also, "Do not let the engine idle to warm up." is in the manual as well.

 

I had the 60k check-up and an oil change recently...that is it. Very few problems with this car since I purchased it a few years ago. Thanks for the responses thus far. I am heading out of town tomorrow morning, so I won't be putting any miles on her this week...but plan to drive straight to my mechanic upon my return. If it is going to leak anywhere, I am glad it was from the resovoir, I guess. I hope it is just a bad thermostat or cap.

Is the spring inside the cap supposed to be out, I don't recall seeing it before?

 

if your caps end in 00... it will need replacing.

 

Check on RennTech, but:
- it is not uncommon for the reservoir cap to need to be replaced, some older part numbers definitely should be replaced
- sometimes it can be a crack in the reservoir itself
- you may have debris in front of the radiators (which are actually behind what looks like the radiators in the intake ducts, but are really for your air conditioning). RennTech has a clear DIY on cleaning those...but you can also have a local mechanic do it.

Good luck. Sorry about the trouble.

 

sounds like coolent is boiling cause pressure to increase in coolent system, thats why overflow bottle fills up cause extra coolent has to go somewhere, if is only doing it at idle then u may want to see if your coolent fans are kick'n in when coolent reaches boiling point?? good luck!

 

Thanks for everyone's help on this...it was just the old style cap. It scared the crap out of me, but she is running like a top again. Man I love it when it ends up being a simple relatively cheap fix!

 

that's great my friend!!