djtnut

Hi there,

I apparently have a small coolant leak in my car somewhere. I started getting the flashing TEMP sign in the instrument cluster this winter on uber cold days in Vermont. i.e. below 10-15F or so. I went to an OEM parts supplier and bought the "red" (aka pink) coolant that is specified for my '03 Audi Allroad and topped it off (took pretty much the whole 1.5 liter bottle). It's been fine since then and then over the past week or so, I've been getting the same warning periodically. First started when it was in the 90's here in Vermont a week or two ago. I called my trusted Audi Indy Mechanic and he suggested bringing it in to get the leak traced and/or just topping it off periodically and keeping an eye on it.

So I went back to my OEM parts supplier shop and bought some more. The guy at the counter said that it needs to be diluted with equal parts distilled water. I said I didn't do that with the 1.5 liter bottle I used up in the winter. He said that it's less important in the winter time because water mixed in is more likely to freeze, but that I should cut it down 50:50 in the summer.

Does anyone do this? I spoke to my Indy Mechanic again about it and he said it's actually fine either way. Wondering what everyone else's experiences are.

Thanks in advance, David

thejulex

You have to dilute it with water in about 50:50 for summer and 60:40 (60 being coolant) for cold climates like vermont for winter.

If you don't dilute, the pure glycol based coolant will lower your cooling system efficiency significantly as glycol doesn't conduct heat all that well. The water part is responsible for proper heat conducting of mixture while glycol is responsible for lowering freezing temperature of the mixture.

djtnut

how do you change it out? do you flush it and then re-add every fall and spring?

fjasper

Get it close to the right mix. If you can calculate the amount remaining in the engine to a high level of precision, you can shoot for an exact ratio if you want, but it's not really necessary.

There's a drain near the back of the engine (on the bottom, of course), and pulling off the lower radiator hose will let most of the coolant out of the radiator. Disconnect one heater hose and use water or GENTLE compressed air to push the coolant out of the core. Once it's all flushed out (there's a diy somewhere) close it all back up, put in G12 equal to 1/2 of the total capacity, then top it off with distilled water. You'll be close enough, and I wouldn't bother to adjust the mixture unless I moved to a different climate.

There are two places to bleed it: behind the power steering pump and on a heater core hose.

I flushed mine several times to fix a bad scale problem (distilled water is definitely worth the extra couple of dollars), and as long as you don't mind getting wet, it's not that hard. The little Prestone flush-n-fill kit helps on the flush, because you can use a garden hose to push out the coolant that won't drain.

If you have a small leak, try some stop-leak. It's cheap and worth a try. Mine started leaking slowly after I got the cooling system squeaky clean (via multiple flushes with oxalic and citric acid), and a bottle of stop leak sealed it right up.

Kneale Brownson

The 50/50 mix should be good for temperatures as low as 35 below zero (F). Leave it in year-round until it's time for a coolant change.