I was viewing a few DIY guides on changing the timing belt and everything but they were not very clear about doing the coolant flush.

Does anybody know how to preform a proper coolant flush for the A4 b5?

 

I've read about several different methods. Which is the "proper" one is up to interpretation i suppose.

The week after I bought my avant, I discovered that the previous owner had mixed coolant. I didn't have the time or desire to flush the coolant myself, so I took it to a local Audi/VW garage to have the coolant flushed and the expansion tank replaced. For $150 they "power flushed" the coolant system with G12 and replaced the tank. According to the guy I talked to, they have some kind of pump thingy that they hook up to the coolant system that forces pressurized G12 through the cooling system, which they run until its clean. Not sure how much of that is BS?

A DIY version of this would be to do that with distilled water. drain the crusty coolant, fill with distilled water, and run the car for a few minutes. repeat until the water comes out clean, then fill with 50/50 mix of distilled water and G12.

If your coolant is relatively clean, that will probably be overkill. You should be able to just get away with draining it from the bottom of the radiator and refilling. Make sure you let it idle for a little while with the cap off the expansion tank to get all the air out of the system.

 

That basically covers it. On a 12v car there's a block drain on the bottom of the engine way in back - the 30v and 1.8T likely have it in a similar place but I haven't messed with those before. That allows you to get the coolant out of the main water galleys and other locations that a radiator drain won't reach.

 

that is possible.. i mean i work at an VW dealership and we have a machine that does that.. but idk if a little shop would own a machine like that unless they do well there. its not a cheap machine.

 

Is it necessary to do a coolant flush with the timingbelt job? It seems a bit complicated for a noob like me.lol Im thinking about skipping this part and having a VW/Audi shop do it.

 

Completely flushing the coolant system is not necessary, but don't re-use coolant either. You're gonna need about 3 liters of G12 mixed 50/50 with water to refill the coolant after you do a timing belt job.