2000 Boxster Coolant Leak and Smoke

[nikolay5567]

Hi everyone,

I recently purchased a 2000 Boxster with 98k miles. When I first got it I drove it about 30 miles to get it home with no issues. The next day however when I was about to park I saw white smoke coming from behind me. It looked like it was coming from the engine bay but the top was down so it could have been from the trunk?

When I got out it was draining a lot of coolant from underneath and when I opened the trunk it also had a good inch or two of coolant pooling. I also looked back and there was a small trail of coolant that seemed to go back for about the whole time I was in the parking lot so it seems it was slowly draining before something else opened up.

I let it cool for an hour, added a gallon of coolant (which filled the tank to the fill line) and was able to drive it about a mile home without problems and with the temperature staying normal. The coolant I added seemed less than I thought was on the ground but I didn't think much of it at the time. The next day the tank was empty again so it looked like it had drained into the rest of the system since there wasnt anything on the driveway. In the panic I had forgotten to raise the bleeder valve so is it possible that was the reason it hadn't initially drained into the rest of the system or is it possible there's a block somewhere?

I didn't see any noticeable cracks in the tank and the previous owner had replaced it a few months ago (although with a third party part).

My current theory is that there was a small crack which slowly drained the coolant until it was low and caused a hot spot (and steam) somewhere in the engine?

I'm thinking of flushing the coolant and replacing the pump, tank, and thermostat with OEM parts just to be on the safe side but is there anything else that could be wrong and that I should be looking out for? The cap was also the old version if that matters but I have ordered an '04' one.

Also as a side note I noticed after it had cooled down that the oil was very overfilled but looked fine in color. Also planning on changing that this weekend....

Thanks in advance!
Nick

[78F350]

Welcome to the forum. Pressure testing the cooling system would be a good diagnostic if you can do it or have it done.

Worst case would be a cracked head which I have seen most often in the 2000 year model. Yours doesn't seem to fit that though since you had coolant in the trunk and no indication of intermix. I still wouldn't throw a lot of parts at it until after doing a pressure test.

It the car 'Tiptronic' or manual transmission? There's a cooling line going back to the transmission cooler on the Tiptronics. The valve for the transmission cooler is under the trunk and is the weak point in that loop.



Aftermarket expansion tanks for these cars are often poorly made. If the previous owner installed the cheapest tank, it's likely they also did the installation. Check over the coolant tank hoses to make sure they are correctly installed and in good condition. It's not in an easy position to work on or see. You may be able to get a decent view by looking through the hole where the engine wire harness passes through the firewall and using an inspection mirror.





Check the hoses, especially the ones that connect at the front of the engine. I recently replaced one that had a 2" long split in it. Another hose that had weakened and bulged and was likely to give out soon. * Those would not lead to coolant in the trunk.



There's more possibilities, but that's what I've dealt with recently. After you reply or maybe after another cup of coffee we can discuss more.

[nikolay5567]

Thank you for the advice! It is a manual so that rules out the tiptronic issues.
I did attempt to pressurize it but it wouldn't hold pressure. I could hear air escaping somewhere around the bleeder valve but I couldn't pinpoint it with bubbles. I inspected the hoses in the area and they all seemed dry and undamaged.

Should I attempt to replace only the bleeder valve and see if that fixes the problem or should I not bother and just replace the tank entirely? Is there any way for coolant to get into the trunk if the tank is not leaking somewhere? (Coolant boiling out faster than it can drain?) The drainage tube works and isn't blocked anywhere.

Thanks again!

[78F350]

If it's an aftermarket tank in there and leaking around the bleeder, I'd replace the whole tank with one from Pelican Parts or FCP Euro.

*Before buying a new tank, I'd remove the bleeder and inspect it. Try reinstalling it. It might not have been torqued evenly or the seal could be pinched.

[nikolay5567]

Cool thanks I'll try that too!

Also the smoke I saw could have just been from the coolant being low right? I didn't get any lights when it happened but I don't know if I should be concerned about any other component?

[blue62]

78F350 has given you good advice.
You say you pressurized the system and heard air hissing out but could not find the leak.
Use a bottle of water with dish soap in it.
Pressurize the system and then start squirting the soapy water on everything you suspect could be the leak.
The soapy water will bubble up.
You need to isolate and identify the cause of your coolant leak.
Or you could end up chasing your tail, spending a lot money and changing parts that don't need changed.

[78F350]

I’m still assuming that the white smoke was steam from coolant exiting under pressure and onto the exhaust.
White smoke exiting the muffler can be from a failing AOS. Deal with the coolant loss first.

[nikolay5567]

As an update I replaced the bleeder valve mechanism and that fixed the pressure issues. Also after driving it a few times the trunk has remained dry and nothing has come out of drainage tube.
78F350 I think you are right and it was just coolant falling onto the exhaust from the trunk drainage holes which was a lot less scary of a reason for smoke than any of the reasons I was thinking.

I'm still not entirely sure how so much coolant could get into the trunk if the tank is actually fine so I'll still be keeping an eye on it.

But thank you everyone for all the help!