sudden coolant leak, then stopped leaking

[Jinster]

I was idling my car today for about 30 minutes when working on something.

Suddenly the car started dumping coolant from around right rear wheel area. It sounded like a hose leak. Initially I actually thought it was the neighbour using the garden hose.

The leak then stopped after about losing 1L of coolant. No oil in the mix.

I then topped up the coolant, it required about 4L, so it was low on coolant already. Although I haven't noticed any obvious leak before.

I then ran the car down the street, sat it idling for a while, the problem hasn't occurred again.

This is strange because the speed of the leak when it happened, and the fact it just stopped leaking straight away. One would think if the leak comes from a broken hose it would constantly leak once the flood gate is open.

Does the Boxster have some sort of "over pressure" coolant dump mechanism? I theorise that if I was low on coolant already, the idling made the remaining coolant boil (it's mostly water, not much of the green stuff in there), and then some sort of pressure valve opened to dump the coolant? I didn't think this existed on the Boxster.

I replaced the water pump 3 years ago, so hopefully it's not that.

What could it be?

[RFM]

A faulty pressure cap is possible, check the last two digits on the cap, it should be 04 or higher, replace the cap if it is not the case.

[pk2]

These things have a habit of cracking the tank back there. It's not always easy to see the crack or where the juice goes. If you do a search you can find out more. Your car probably runs hotter at idle than it does buzzing down the highway making a higher pressure build up forcing the fluid to pop the cap (above, goes to the flood gate theory) or squeeze out the crack. Also if your low on coolant your temps will build up.

I would keep driving around with an eye on the temp gauge. and check the coolant often.

Regards, PK

[kbrandsma]

If you have a faulty fill cap, it can cause the relief valve to trigger. That happened to me last summer and I ended replacing both the radiator cap and installing a new relief valve. I would try the cap first and then determine if a new relief valve is needed.

Edited November 9, 2010 by kbrandsma

[BoxsterTaff]

Boy my luck is on a run!

Trans rebuild, new O2 sensor, new fuel pump and now coolant all over the floor!

Looks like the same issue that Jinster had. I took a run (ironically to see if the CEL light would come on for another issue - I bought a code diagnostic tool, will let you all know how it performs) for 30mins, then left the car to idle for 10, after which the coolant came gushing out of the overflow pipe inboard of the rear right wheel. Temp was at the right edge of the 180 letteing on the cluster gauge.

So, I've ordered a new cap (mine was original, ended in 01), checked it for leaks (dry as a bone in the tank.....old leaves under the trunk liner(?!?) testify to that.....

My question is guys, do I need to be worried about any other causes, or have i just had a dempnstration of the reservoir cap issue?

Right......may as well clean the MAF and intake valve whilst i wait for the new cap - that was the original plan for today :-)

Pic of the overflow for those who may have the same issue....I hope you don't!

[BoxsterTaff]

just drained the coolant following the pelican parts guide, new cap and 3gal of Porsche OEM coolant on the way (thanks to this forum....I had 5gal of O'reiley coolant ready to go......but really don't need a jelly soup on my hands right now!!!).

Coolant came out a brownish green, thought oil at first but could not see or smell any in there, so I assume its rust from being in there for 14yrs? Pic attached if anyone has seen old coolant before and can confirm the color of 14yr old Porsche coolant!

Thanks

Andy

[Loren]

just drained the coolant following the pelican parts guide, new cap and 3gal of Porsche OEM coolant on the way (thanks to this forum....I had 5gal of O'reiley coolant ready to go......but really don't need a jelly soup on my hands right now!!!).

Coolant came out a brownish green, thought oil at first but could not see or smell any in there, so I assume its rust from being in there for 14yrs? Pic attached if anyone has seen old coolant before and can confirm the color of 14yr old Porsche coolant!

Thanks

Andy

Looks normal to me.

[BoxsterTaff]

Thanks Loren - that puts my mind at rest. Wasn't as bad as I thought to drain the old fluid.