Coolant Leaking - Expansion Tank Bad?

[cadetjoe]

So, I just got my Boxster back from the repair shop yesterday (I took a curve too fast and slid into a curb - had to have the rear struts replaced). Driving home from the shop yesterday, and on my commute this morning, didn't notice any problems, car is running great.

When I get in the car to come back home, I got a low coolant warning. I has some coolant with me so I filled it up and headed home. I noticed the oil temperature was about 20 deg hotter than normal, but the weather today was very hot, so I figured that might be all that it was. But then, I started getting a low oil pressure warning that would come on whenever the engine idled, but went away if I gave some throttle.

Got home and checked everything over, and noticed a puddle of coolant in my driveway. Whenever I put more in it just leaks right out .

The coolant is coming from the overflow hose. I jacked the car up and looked over all the hoses, and didn't notice any leaks or damage to any of them. Whenever I try to put more coolant in, it immediately comes out of the overflow hose.

I pulled up the carpet in the trunk and took a look at the coolant resevoir, but didn't see any obvious leaks. When I pour coolant in, it just seems to disappear right out of the fill compartment and comes right out of the overflow hose.

My guess is that there's something wrong with the resevoir, but I'm not sure. My first thought was that something got damaged at the repair shop - it looked like they had pulled up the carpet in the trunk looking for the strut mount when they replaced the struts. I've never had any sort of fluid leak problems with this car before, so the timing seems suspect.

Would could be causing coolant to leak like this? Would running the engine with little to no coolant affect the oil pressure?

I'd appreciate any thoughts or advice you folks might have

[Loren]

Check you coolant tank cap or just replace it.

[wvicary]

Remove the plastic cover over the expansion tank bleed valve for inspection. You have to remove the coolant and oil fill caps to remove the cover. You have an oil temp gauge? I would be worried about the low oil pressure warning light coming on- have you checked the oil level? What did the coolant temp read?

[cadetjoe]

Remove the plastic cover over the expansion tank bleed valve for inspection. You have to remove the coolant and oil fill caps to remove the cover. You have an oil temp gauge? I would be worried about the low oil pressure warning light coming on- have you checked the oil level? What did the coolant temp read?

Hey wvicary, thanks for the reply. No, sorry, I don't have an oil temp gauge - I meant the coolant temp gauge. It was around 200F. I removed the plastic cover and didn't see any leaks.

I waited for the car to cool down and then refilled the coolant reservoir last night. There was no leaking from underneath the car this time.

Took the car for a short drive this morning. Everything started normally. Once the engine warmed up, the temperature started climbing back to 200 again - about 20 deg above normal. After about 5 miles, the low coolant light came on again. When I looked in the trunk, I noticed a lot of evaporation coming off of the reservoir. Still no fluid leak under the car. Once everything cooled down, the coolant level was right at the "min" line.

I'm gonna try what Loren said and get a new cap today. It's cheap (like $20) and hopefully that's all the problem is. Maybe the cap is not holding pressure anymore and letting the coolant evaporate out?

BTW, I check the oil level regularly, and it's fine. And I didn't get any oil pressure warnings when I went for that short drive this morning.

[wvicary]

Be sure that the cooling fans are coming on.

[cadetjoe]

Just did a test drive with the new cap. Temp remained steady at what it is normally, and no warning lights. No evaporation out the back. :D It looks like all is well.

Wow, I make a long panicked post, and Loren solves the problem in exactly nine words. Thanks Loren!:thankyou:

Hopefully, nothing else will go wrong this week, and I can take the car to my first autocross this weekend :drive: My luck seems to be thin this week - while conducting the above test drive, got pulled over in a low speed zone I had no idea existed. Cop let me go with a warning, though. Also found out my wheel lock key is cracked, and its gonna take a week to get another. Just have to avoid getting a flat between now and then...

Thanks again guys for your help.