Anyone here have to top off coolant once a year?...
 

I've noticed that my Boxster's coolant expansion tank level drops from the full mark to halfway between full and min level about once every 10 months, so a very slow lowering of coolant level over a long period of time. Temps are always in normal range and I don't see any condensation in tank area or loss of coolant below pass tire. Can there be a leak that slow, or does some coolant exit bleeder as a normal process? Engine oil is not showing any indication of coolant getting intermixed, so don't think there an internal leak.

I don't. Have you checked your water pump? As they age coolant sometimes gets past the bearing and leaks out slowly. Easy to check as you will see coolant residue.

I would say you have a leak. We have customers that go several years without any coolant level adjustment.

Thanks guys. This is a view to my bleeder valve. Guess there is a little dried up coolant there. Does that look like it is the cap or bleeder screws?
http://i869.photobucket.com/albums/a...psdn0ubxvb.jpg

How old is your reservoir? Has it ever been replaced?
 

My 2001 Boxster S did the same thing and it got worse overtime. If your tank is yellow it is time to think about replacing it before you end up with a pool of coolant under your carpet. Little cracks develop all over the bottom of the tank over time. It's not the easiest part to replace but its worth doing. After I replaced it - zero coolant loss.

Thanks. My tank was replaced at around 38K miles (now at 73K). These tanks stink, so I'm probably due.

My Boxster used to do the same. Ultimately, I found that the water pump was weeping and the coolant was evaporating before it could drip. I didn't do anything about it until my water pump started actually dripping.

This is what it looked like:
http://i1114.photobucket.com/albums/...psb0c758b9.jpg

That's exactly what i was going to say. You wouldn't see a puddle for that slow a leak but you will spot signs of water evaporation underneath.

I'll check down there. Water pump was replaced at 58k miles, so not too old, but you never know. Thx fellas.

Interesting thing is that after driving the car, I notice the coolant level is now at the Max mark, so it has expanded up. So assuming the level is topped off to the max level at cold, when the car warms up, it'll have to release the excess? Then, it's better off I just leave at between max and min then?

I had a slow leak after I replaced all the coolant hoses - the new 3-way hose was faulty. I had thought it was leaking at the end junction to the solid pipes but the coolant was actually seeping from the hose 3-way intersection. Ugh.

2000 base 2.7

As long as it's between the marks and your temps are ok then i wouldn't worry too much.

I'm finding the OEM replacement pumps just don't last. It's turning into a 2-3 year maintenance item, just like flushing brake fluid.

I don't see any signs of coolant residue on the hoses below the car. No intermix seen in either the coolant tank or under oil cap/fill tube. It's been like this for years on my car (ever since I got a new coolant tank many years back, in fact), so I'm not sure what to think. Once a year or so, it's down from max to halfway between max and min, so I'm gonna leave it for now and see what happens.

I've topped off my coolant tank a couple times since I've picked up my 2001 Boxster base, a couple years ago. Previous owner I think provided receipt of the expansion tank being replaced right before I got the car, along with a new OE "Blau" brand (but not genuine Porsche) cap. Ive noticed no evidence of leaking or evaporated coolant crust down below. Since the cooling system is such a big capacity, and may be difficult to get all the air bubbles out, I figured perhaps it may just be necessary to top off very infrequently. I can't really say the coolant level has completely stabilized, however. I try to not remove the cap more than is necessary. Never had any performance problem with the cooling system. Not sure if this helps, but for what it's worth...

Thanks, this sounds like what I'm going thru with my tank too. Will see if things change I guess.