Coolant Loss

[openwater]

Foolishly let my '99s (~53k miles) coolant get an inch or so below the 'Min' level before topping up to full on Saturday. Historically I've had no problems with overheating or coolant loss, in fact no other work except clutch and tires...

Today while driving the red overheat warning light starts flashing, all the time the temperature remaining right at 180. (Outside temps have been 65 to 80 lately here in San Diego). Stop, check the reservoir and it's bone dry. Luckily carrying the extra coolant and water from Saturday so I fill as best able (~2 in below 'Min')and return home, less than a mile. Temp stays at 180, no flashing light.

Get into the driveway, stop and get under the right rear. Traced dripping coolant to just in front of the right rear tire, dropping off a low point about 2 inches inside the right edge from what appears to be a jacking point...

With engine off, 15 minutes later the resrvoir in empty again

Any thoughts?

Coolant looks 'fresh and clear' no other engine issues.

Thanks!

[mrmickeymouse]

Check this out:

http://www.dietersmotorsports.com/tech/tech9-03-2003.htm

Scott

[openwater]

New revelation.... After removing the reservoir cover (looking for the bleeder valve) I found tons of antifreeze residue and a small overflow port which runs down through the center of the tank, also caked with moist residue. I suppose it's there to handle and oil or coolant spills while filling...

Is it possible that my pressure cap is shot? After pulling the carpet and closely inspecting the tank it looks in very good shape, no residue on the sensor or around the base. Also, there remains about 3 inches of coolant in the tank, below the view of the check window, but no evidence of further leakage since it cooled down 3 hours ago.

I know the easiest way to check would be to get a new cap, fill the reservoir and go throughout the bleed process... does this make sense though?

Would my topping off last Saturday make this failure more likely?

[donv]

You could try just filling it again, reinstalling the existing cap and running the engine until at full temp with the cover/carpeting off and see what shows... seems you've found the area where it is coming from, just not the specific point - or why.

[Alienz]

I had a similar problem with the overheat light flashing. I turned the car off and back on, it was gone. I didn't check the collant though. Mine is a '97, is it air or water cooled. The site mrmickeymouse posted says they only '99-up are water cooled. But 986faq.com says '97-up are water cooled.

http://www.986faq.com/2-0/stdequip.asp

[Automon]

I also had a problem with dripping coolent after i had my oil changed and the top off my coolent I pulled in the garage and the car was dripping from under the car. what I found was that when they added coolent it must have caused an air pocket in my system which made it overflow on to the ground once the system was pressurized. I have not had a problem after that day and the car is running perfectly. I have a friend and we just supercharged his Z06, (that's right supercharged) anyway we had to drain most of the coolent . Upon completion we re-filled the system which cause air pockets, which caused the car to over heat. We then slowly added coolent until the theromstat opened and the system started to cycle which cured the problem.
Automon

[mcd]

on my 97 a week after purchase,a simalar thing happened. i pulled into garage ,lifted on rack found out water pump had failed. where the serpintene belt goes around the water pump if yours is bad that pulley will move quite alot. i replaced this part myself with minimal problems. if this is infact the problem feel free to e mail me i will be glad to hook up by phone and help if you want,if you do your self make sure the bolts all go back exactly where you took them from , some are different lenghts. hope this helps someone good luck.also there is a bleeder directly under the plastic where oil fill and radiatorfill are in rear trunk.lots of luck agian MCD

[mjbliemel]

My mechanic noted that my cap was getting weak when I had my 60K service done, so the next time in I had it replaced. It's a $14 part. I suspect you have/had a weakened coolant tank cap.

[mjbliemel]

RE: Air cooled Boxster claim.

First I have ever heard anyone claim the Boxster engines were air-cooled prior to 1999. That's a hoot!

[mrmickeymouse]

Need to read the article: Dieters never said it [Boxster] was air cooled, that is a miss quote.

This is what Steve said,

"While Porsche has gotten along with air-cooling for their sports cars for the past 50 years or so, it has come to my attention that ALL Porsche models are water-cooled, and have been since 1999."

This is true....

Need to clean that up, since I posted it.

Scott

[CJ_Boxster]

You might want to check your coolant cap to make sure its the most updated cap... if it cant hold pressure (the old cap) it will not seal and fluid will leak out and your temps will increase.

[bmx672]

How do you know if its the newer cap?

(not to hijack the thread)

[saaber]

Originally Posted by bmx672

How do you know if its the newer cap?

(not to hijack the thread)

Last 2 digits are either 01 or 02 for the newer caps. Old caps say 00 etc..

I suggest taking off the oil cap and coolant cap and then remove the rubber flap. This lets you see if the bleeder/pressure valve or cap are leaking. If there is coolant on the top there it is probably one of those two and you should be able to see where it is coming from. If no coolant there on top then look under the carpet in the trunk to see if it is a cracked tank which is extremely common. If no coolant in either place then likely a hose, etc. in the engine bay or even one of the big radiator hoses in front of the engine underneath. My bet is it is a cracked tank.

While failed "bleeder" valves, caps, and a hose can certainly be a source of the problem, it seems like most of these problems are due to cracked coolant tanks which you will see all over the forums such as renntech.org and here. Mine cracked in the middle on the bottom where you can't see it unless it is removed. It is a DIY job but don't be fooled by some of the posts that say "I did it in 10 minutes" etc.. That's crap! It is not a fun job but you can do it yourself if you are handy. Also most of the tanks now are for the 987 and don't have a premade hole for the dipstick so if you need the hole just drill it out before you install.

If it is the tank, sunset imports had them for $176 a while back. Check renntech for "special" pricing as they are a sponsor there.