saline

I'm going on a trip tomorrow morning and I want to get an early start. I noticed today that my coolant level is at "Minimum." Will I do any damage to the system if I top it off with regular fresh Prestone? Otherwise, I'm going to have to wait for the dealer to open.

Third-Reef

I would not use the prestone. Instead top it up with distilled water and you will be fine.

Kevinmacd

Yup agree with Third-Reef just distilled water.

rmc1148

^Yes.

Macster

There is a reason why the level is low and that is because the cooling system has a leak.

You are thus heading out with a Turbo with a cooling system leak. That is not a good thing to do.

Now the problem could be with the cap but it might be the coolant tank, the water pump, one or more coolant hose fittings, or even a radiator (or two or even...sigh... three).

You really should identify the leak and have it fixed before you drive the car.

993GT

what colour coolant is in the car currently? if green/yellow, then use Prestone, etc for top-up..
if pink/red use distilled water, or if convenient,visit local VW/Audi dealer and ask for a bottle of G13 coolant(gallon jug is $20-30)
Distilled water is the safe path, but ensure the mixture is safe for the winter months if driven/stored in cold temps.
might be surprised how much it takes to top-up, go overkill on volume you purchase...also inspect for leaks/ cause of loss..

"02996ttx50

while adding distilled is the safest route if one doesn't know what is in there. i prefer to maintain a healthy balance of 50/50 coolant/distilled and i keep a pre mixed 50/50 solution of vw/audi g13 pre mixed for topoffs.

i have no leaks but find on occasion in extreme temps that an occasional top off is indicated. i call it evaporation, but dont understand how/why. but what's a once a year topoff? not much.

Macster

The cap can be leaking. What can happen is the coolant is particularly hot and if the engine is shut off with the fans running because the coolant temperature is elevated, the heat load of the engine can raise coolant temperature and pressure and the pressure can overcome the cap and leak vapor.

Because vapor -- water vapor -- leaks while the coolant level drops the system doesn't lose anti-freeze, so just adding distilled water to bring the level back up doesn't dilute the mixture.

Another source of a loss of coolant is the water pump seal. My info is the seal can leak. I was told a bit of an anti-freeze stain from dried anti-freeze is ok, but one should never see any wet coolant dripping.

993GT

my bet is a radiator core has a small weep/leak...

James88

I just had this very similar issue with mine, I had it pressure tested and it all checked out ok. I was advised to to just add distilled water.

"02996ttx50

appreciate the info macster even if i dont fully understand it. however, nothing you can say to to me will convince me that adding water to a factory recommended 50/50 coolant mixture will not further "dilute" it. that does mean i dont have a pinhole leak, but i check everything on my car religiously/obssessively and a once a year topoff hardly seems excessive ( let alone obsessive ) when coolant caps have breathers built in. just my 02.

Kevinmacd

If im not mistaken the coolant tank has a pressure relief valve in it. its the spring loaded valve on the front top of the tank.

"02996ttx50

..right, but its not the "blue" cap itself? is it? but rather the black cap that has the snap release on it, no? and why we need to pressurize the system on a coolant flush by leaving the breather unsnapped, until it normalizes the close it. i have a reasonably new expansion tank ( not cracked/yellowed ), and still get occasional excess out the breather cap? that make it onto the motor mounts area and is that milky white dried coolant. never enough to matter, and once topped off, i'm good for the hot months, which are now ( mostly ) behind us.