coolant flush - 4KS

[audi-driver1126]

Hey guys, im going to buy a new Beck Arnley coolant temperature sensor soon, ive got one at a local parts store, priced at $48.50 Before i put it in, i would like to flush all the old coolant out. its a grimmy mix of water and anti freeze and it reaks like fish...So basically i just want to know how you guys would go about doing it and any tips of cleaning the internals in any way

[Rogviler]

Before doing any flush it serves to take the old thermostat and break it so it stays open. That'll save you a lot of time so you won't have to wait for it to open on its own. You should replace it anyway (might as well, while you're in there).

So, if you want to get crazy...

First you want to flush with a detergent. Dishwasher powder is about the best because it doesn't foam up but it cuts grease. Use about a cup mixed in a gallon jug of water. Drain the old coolant and fill it with this, adding more water to fill the cooling system.

Then you just drive the car around for awhile. I don't think you can really leave it in there too long, but a single trip is sufficient. Drain it and flush with plain water.

That will do a pretty good job on its own, but it's also a good prep before doing an acid flush. You can either buy a commercial product (I know Mercedes dealers carry it, not sure about VW), or you can make your own with citric acid powder. Stores that carry a lot of vitamins and tofu-based foods will sell it.

For your engine size I would use maybe half a cup. Less is better than too much. Mix that with a gallon of water and do the same procedure as with the detergent, EXCEPT you don't want to leave it in for more than 15 minutes or so, and I would also not run it through your heater core, since those are pretty delicate. Just let the engine run for a few seconds to circulate it, shut it off and let it sit for the 15 minutes. You don't want the engine to get hot at all. Then drain, flushing thoroughly with water.

The acid will definitely leave it squeaky clean and get rid of any junk that has built up.

Now the important part: Don't refill it with green antifreeze. It's hard to get the G11/G12 stuff, so I've been using G05, which is the best substitute you'll likely find. You can get it from Amazon.com (not .ca though), but parts stores sometimes carry it or can get it.

If you do fill it with green you'll have to drain and flush it every year or you'll start to get buildup again. I'm convinced that a lot of the cooling problems with these cars is due to many years of green coolant, which nobody ever flushes. With G11/12 and G05 you don't have to flush it every year. I believe they're rated for 3-5 years but they're not going to plug everything up if you miss that schedule.

If you don't want to get crazy...

I would just run clean water through a few heat cycles, then do a parts store flush (like Prestone), more water, and then refill, again avoiding green coolant if you can.

Regardless, remember to let the engine cool before draining and don't add cold water/coolant to a hot engine (both can cause cracking or warping).

-Rog

[audi-driver1126]

Thanks! That's a lot of help, I think I'm going to do the dishwasher detergent thing. That is easy enough for me to do. I'm on a tight budget right now but I think I can do that.

For now, I'm not sure if I can get a new thermostat. How much are they usually at a parts store?

[Rogviler]

Thermostats are usually around $20. I can't remember if you can put the housing back together without the thermostat or not on these... Some cars you can, other times it leaks.

Anyway, that's not a big deal, it just saves time. It's pretty much a must if you do the acid flush, but otherwise you'll just have to run it until the thermostat opens.

-Rog

[onlyaudis]

Just did mine. you can buy those kits that attach to the heater hose. I replaced my 87C thermostat (that had broken in pieces) with an 80C one, and also did a lower temp fan switch. Car runs way cooler on the gauge now. My audi mechanic told to actually use the green stuff in these older iron block cars, just get a good brand of it and change it every 2-3 years. The current "green antifreeze" is much better than the stuff that was out there 10 years ago. I also use redline water wetter

be careful on those 6mm bolts that hold the housing down--they bust off easily. soak the heck out of them with Liquid wrench. be sure to spend some time cleaning out the fill bottle. it has baffles and screens and it takes a lot of time to clean all the gunk out of it. I ended up replacing my top hose with a nice rigid silicone one from 034 motorsports. Mine had gotten soft and was collapsing at the top bend when it got hot. they have a whole silicone hose kit if you want to replace all of them

[Rogviler]

Since we're talking about a budget here, only 1 or 2 drops of dish soap in your coolant will accomplish the same temmperature results as Water Wetter, but without the corrosion inhibitors (i.e. you want to use it with antifreeze). Just a drop or two so it doesn't create suds.

Use what ever antifreeze you can get, but keep up on regular changes if you use the green. All I know is with the green I see sludge, with G05 I don't...

-Rog

[audi-driver1126]

yesterday i did a quick water flush only for the sake of doing somthing to pass time. I had to take a heat gun to the lower rad hose so it would loosen off. It appears that someone had been in there before and they bent the metal on the radiator where the hose fastens on. I ran my finger in and around the inside of the radiator and i dont have any sludge or slime going on in there. Just stain from all the water minerals and coolant.

So as far as i know, things seem good inside. Im running it with just water for now until i get my new coolant sensor.

The sensors effects are so annoying. I cant even start the car from cold anymore. I have to unplug it, start the car without the sensor. (i guess the ecu figures the engine is cold?) so then it fires up good and i have to plug in the sensor again while its running and constantly hold the throttle down just a tad until its warm enough to keep itself on its closed loop thing.

anyway, im going to pick up that sensor soon and then look at a good resourse for the required anti freeze

[audi-driver1126]

change of plan, my Beck Arnley has been delayed, going for the more expensive Borg Warner.

any idea if Borg Warner is any good? it has to be for the price im paying for it...