Cooling problems
 

Last Monday I took my boxster up to some mountains and was having a great time, until it broke down. It turned out to be the harness on one of the coil packs had come loose. Long story short I started driving home, and was sitting in traffic and after I started moving again I got a low coolant light, I pulled over and shut the car down and coolant had started running out of the overflow. I let it cool down a bit and started driving again, and probably only made it about 5 minutes until the temp gauge started creeping up. It ran up to probably around 210 and I shut it down before it pinged all the way up. It didn’t run poorly but it didn’t seem happy. I called a tow and waited, I cranked the heat to try and cool it down but the air was cold.

When I broke down the first time I noticed a little coolant residue around the expansion tank cap. I noticed some leaking from the expansion tank as well and have stripped out the trunk carpet.

So far I have been able to confirm the expansion tank was leaking, and the water pump had some play in it. Could the tank just have cracked from all the pressure?
I’m replacing the tank, water pump, thermostat, and the heater core (smells like coolant when I would turn the heat on in winter occasionally). The car starts right up and seems to run and idle fine, no exhaust smells or intermix or smoke. Is there anything else I should worry about, or has anyone else had a similar experience? I feel like it will be fixed once I get the new tank in and bleed the system, but I always worry about a worse case scenario. It’s a 2003 s with 133k.

Mine puked coolant and over heated, all from a bad cap. Id start by pressure testing the cap and if it's good, then pressure test the system. Simply throwing new parts at the system is not the best way to go about it. Just my 2c though.

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How old is the coolant tank? Had one crap out like yours, but in the middle of a national park. NOT a short, cheap tow!
I believe those tanks are wear items, like oil and plugs.

A couple of things - check your cap - Porsche has superseded the cap several times due to problems with leaking - the cap you should have part # ends in 04.

Coolant tanks are sneaky - they'll expand when hot and allow leaks, then contract when cool. If yours looks poor - visible cracks, heat stressed, etc, your tank is a likely suspect.

Very important! In replacing your cap and tank - DON'T cheap out and go with an aftermarket tank!!! Spend the extra coin and get a Porsche tank and cap. There's many, many stories about failure of aftermarket caps and tanks taking a dump soon after installation.

Same with your water pump - buy a PORSCHE pump - not an aftermarket cheapy. Again, lots of horror stories about aftermarket pumps.

These are NOT items you want to purchase from Rock Auto or someplace from eBay or another cheap replacement.

I think it’s original, it’s not horribly discolored like some I have seen, but the inside is pretty nasty looking and stained. I’ll be able to install it tomorrow, weather permitting.

I think a number of things failed just from pushing the car hard. The car fax shows the pump and thermostat were replaced 30k ago and 5 years ago, but all I could see was silicone gushing out from around both so I got curious. I don’t think the pump was replaced, the bearing had a lot of play, and was the same level of corroded as the rest of the engine. they re used the original gasket and just loaded it up with sealant. As for the thermostat they didn’t even use a gasket, only silicone. After seeing that level of work I figured it was due for replacement. I had let it idle up to operating temp and bled the system with the new pump but the pipe coming off the thermostat was cold still, and the heat was still blowing cold.

I’ll have the new low temp thermostat, and hopefully the tank installed tomorrow and be able to see what the situation is after that. And yes, I did spring for a new cap as well!

Mine looked pretty grimey on the inside, but not the worst I’ve seen. After it had gushed out everywhere I pulled the carpet back around it and saw it running down from the hoses. It’s all soaked into the foam against the firewall now

Ahhh, nevermind my previous comments then, if I found what you just described I'd redo everything in the system too lol. Id try to backflush also, silicone can shower bits into the passages and cause plenty of problems.

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As luck would have it, I took my car out today for the first hard runs of the season. Wifey went with me and then we stopped for coffee afterward. Pulled into the lot and there was coolant dumping everywhere. Popped the trunk and there's coolant all around the cap. Floor is bone dry though.

I'm starting to think that replacing the cap should be a yearly preventive maintenance on these cars.

Unless I've just destroyed my water pump and got extremely lucky... I'll find out when the new cap gets here!

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I think the cap was the beginning of my problems, that was ignored, and then things went downhill from there. See what the cap does and make sure you refill and get the air out. Something I saw someone do as a temporary fix was put nylon tape on the tank threads to seal the cap better.

I got it back on the road today, runs as good as ever, so far so good. Runs much cooler than before with the low tstat, and I believe I have most of the air purged out of the system. In the old coolant I would see some occasional bits floating in the tank but it’s much cleaner now. May your luck be better than mine, but don’t worry, water pump and thermostat isn’t anything to be afraid of if it comes down to it.

I've done 2 tstats now actually. The first was an ln engineering, it failed after less than 2 years smh. Now I have a BW and it's holding up but only 1 year old.

For purging the air, I drive around for a week or so with the purge valve opened. Seems to work well and I don't fill with the complicated procedure Wayne describes or buying an airlift. Just to of after every drive until it stays full.

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Hopefully my new ln lasts longer than that. I’m putting off the heater core for now because I’ll be taking the car on a trip this weekend and don’t have time. Hopefully it’ll last after going through some mountains again, excited to find out though.

A "bone dry" rear trunk CARPET doesn't necessarily mean the cap or the coolant tank isn't leaking......(ask me how I know).

I thought mine wasn't leaking until I removed the rear truck fabric liners, and LIFTED UP the composite raised trunk floorboards......that's where the coolant was pooling up! Only a few drops of coolant would leak out through some of the small trunk seams and rubber plugs onto my garage floor.

The plastic coolant tanks eventually develop tiny spider cracks that only leak after the coolant comes up to temp and the pressure causes the spider cracks to expand and leak. (my plastic tank was 20 years old) I wound up placing a wadded up paper towel around and under my plastic tank and took a long drive to heat things up....when I arrived back home the towel was wet....not soaked but wet.

Just a side note on what you think was 210 temp. Low speed fans do not turn on until around 210, high speed around 216. The temp gauge arrow on mine at 210 is mid 0 in the 180. 210 isn't really all that hot. I think. My 99 has new radiator fans, water pump, low temp t-stat new fluids and radiators were cleaned out with bumper off. On hard drives I'm always reading that 210 range. I have a live reader that shows me all specs on my phone. My tank never leaked and coolant is always stable. All of this for your reference.