Coolant/Flashing red temp light

[scooter]

Hello again!

So, I bought my 99 NB ("Scooter") about 3 years ago with 81k on it, and it now has 117k. For the most part, it has given me little trouble and has been a great little car. Not knowing what its maintenance history was like, I had the water pump/timing belt/serpentine belt replaced at 85k. The mechanic (an independent one, not a dealership) also did a coolant flush. I didn't think much of this at the time.

The past two Monday mornings (today and last week), about 20 seconds after starting my car to go to work, the temperature light started flashing red and beeping. This had never happened before, and it scared the crap out of me. The first time, I immediately pulled back into my parking spot and popped the hood. The oil was low (as it usually seems to be), so I added a little. Everything was still cold. I didn't know what else to do, so I started it back up. The light stayed steady and blue until it warmed up and I had no more problems the rest of the day. I came home and did a little research and learned that it might be my coolant level. I checked it and, sure enough, it was below the low mark (as far as I could tell -- why does it have to be so hard to read?). I read that this could be remedied by topping it off with coolant and/or distilled water. I kept reading things like "G12", "VW-specific", and "don't mix coolants!!1!", and it suddenly occurred to me that I didn't know what type of coolant my mechanic had put in it, but I was guessing it wasn't G12. So I put off doing anything about it, especially since the light didn't come back on for the rest of the week.

But this morning, the light came on flashing and beeping again. I called my mechanic to find out what he'd put in it, and he told me "Dexcool". I've read conflicting information about this product being used in VWs. I've read people saying "Don't ever use anything but G12" and other people saying "It's okay to use something else as long as you flush all the G12 out first" and yet other people saying you can mix G12 and Dexcool. Can someone straighten this out for me, please?

I'm also worried that Scooter may be leaking coolant. I've never seen any on the ground where I park, but why else would it be so low? How can I find out if there is a leak?

Thanks, everybody!
Jenny & Scooter

[hako]

If Dexcool is phosphate based (red) it should be OK...but if its glycol based (green)then it may react to G12 and "maybe' start turning to jelly (but not instantly!) Its not witchcraft or something specific to VW - just 2 different types of coolant.
Re the leaking - the coolant that leaks is at boiling point and therefore evaporates instantly (usually)...it may leave a powdery deposit which is what you should look for.

[Smileybug]

How long after the water pump replacement did you get your flashing light and low coolant levels? I had my water pump replaced this summer. I guess about 2-3 weeks later my coolant light started flashing at me. Pulled over into a parking lot and popped the hood, hoping it was the coolant and not something else! Sure enough, my coolant was below the min line. At first I got worried, as I have never leaked coolant...my car has been great and I never have to top off coolant or oil so I was a bit surprised. Talked to my bf and he snapped some sense back into me. When they replace the water pump, they have to drain the coolant. After replacing, they fill it back up. However, there are air bubbles in the lines so it takes time for the bubbles to get worked out. Once they do, the coolant level drops (as it fills in those spaces). So I would fill it with water enough to get it to where the level is supposed to be. So I wouldn't be very worried right now. Get it topped off and then wait and see if you are low again. Once I topped off my car, she's been fine.

As for the coolant, I only use G12. I wouldn't go using different kinds. G12 is what VW wants you to use. That's also why I go to a local VW shop and not just any mechanic, as I know they will put all VW oem parts on my car, unless specified otherwise (like putting the metal impeller water pump on my car), and use VW approved oils, coolant, etc. Mixing coolants could end up with problems. When my bf got his '95 Passat (the switch of coolant type happened in like '97 or something I think) the previous owners had kept using the old coolant. So he got it with non-G12 coolant in it. So naturally, he did a coolant flush, and added the G12. Then he started having leaks because of the reaction of the 2 coolants. His coolant lines did not like having this new coolant in there! But since this other coolant hasn't been in there for long, I wouldn't be too worried. But I personally would get it flushed again and get G12 in it.

[macdave]

Dexcool eats up some types of gasket material, even in GM engines. I'd stay away from it.

[fohveh]

As mentioned, if there is no leak anywhere it was likely air entrapment in the system somewhere, so once it burps out your level will obviously go down a bit. If it is leaking check the thermostat area, I have done timing belts and pump changes often for friends and have found more often than not the block where the thermostat attaches to rusts just enough and allows coolant to slowly leak down across the oil pan and then onto the ground.

[nyum96]

Yep, Dexcool in my GM engine ate the head gasket... you should see all the rubber hoses now.. bumpy and cracking. That was at 70,000 miles. Corroded the aluminum too. Now has G12 Plus in it.

Check for a leak. Just replaced my radiator in the VW and also check to make sure your radiator fans work.

[scooter]

Originally Posted by Smileybug

How long after the water pump replacement did you get your flashing light and low coolant levels?

Well, as I mentioned, I had the water pump replaced (and coolant flushed) about 3 years ago. The flashing light only started a week ago. To be honest, I hadn't really been keeping track of the coolant level until now. Every time I looked under the hood, I just glanced to make sure there was some in there. Anyway, I doubt it could be because of air bubbles at this point...

Originally Posted by macdave

Dexcool eats up some types of gasket material

Originally Posted by nyum96

Yep, Dexcool in my GM engine ate the head gasket

Yeah, I was rather alarmed after I got off the phone with my mechanic yesterday, googled "Dexcool", and this was the first result.

I think I will top it up with some distilled water for now, and see if I can convince the BF to assist in flushing and replacing the coolant in the near future.

[D2Beetle]

Originally Posted by scooter

Well, as I mentioned...

Yeah, I was rather alarmed after I got off the phone with my mechanic yesterday, googled "Dexcool", and this was the first result.

I think I will top it up with some distilled water for now, and see if I can convince the BF to assist in flushing and replacing the coolant in the near future.

Yea, I'm bad, I smiled the entire time while reading the trials and tribulations regarding DexCool.