JJm64123

Hey all, so I i'm having an issue with my car's cooling system. I knew the heat wasn't blowing hot and saw the previous owner put in green coolant so I figured I needed to do a good system flush. So today I ran water through the system until it came out the bottom of the radiator clear, and disconnected the 2 lines to the heater core and let some CLR sit in there for like 2 hours. After I drained out the CLR is hooked the lines back up and tried to run some coolant flush through the entire system. The heat ran warm for a few minutes and than started going cold again. And it seems like I couldn't get all the air out of the system. I cracked open the screw on the top of the metal coolant line and pulled back the right side heater core line and air just kept hissing out of the line. What am I doing wrong? Do I have a more serious issue like a bad water pump or stuck thermostat? One small thing, I am going to try to replace the coolant cap tomorrow. I feel like its not locking closed like it should. Any help would be great please. I have been trying to watch videos and read posts and I really want to get this before I have to bring it to a shop and pump crazy amount of money.

lyleswk

So if I understand, it isn't overheating, it just isn't giving you heat? If so, One 2 hour dose of CLR soaking in the core probably won't do it. I put 2 bottles over 2 weekends. I started by putting about a third of the bottle and letting it soak 2 or 3 hours.with the first bottle. With the second, I split it in thirds and let it sit overnight, Lots of scaly stuff still coming out even after the last one and I only get heat when the car is above ~2000 RPM for a long time. Bottom line, when the core clogs, it is seriously clogged. Take a look at the link for more discussion on it

https://www.audiworld.com/forums/a4-...-core-2966763/

JJm64123

Yea I guess I’m going to try to put more clr in tonight. I noticed the water was hotter on the right side hose than the left side on the heater core. Like I said before air was still coming out of system for a long time so I guess I will let it sit in even longer. I guess I was worried that the CLR was going to eat throug the metal. But I guess at this point it may have to be changed anyways if I go that far with it. One other question, if the cap is not sealing right will that not allow the system to pressurize and bleed all the air out?

Yoop

After the CLR has sat in the heater core make sure you attach a couple lines to it then flush it out with water, both directions, before you hook the lines back up. You don't want to flush all that crap into your engine block and you'll get a better flush using a hose on the heater core.

JJm64123

Oh yea I did that. And I thought I was going to have some luck because the water flowing through from the hose was actually moving pretty good. I guess not enough though. I guess I’m going to let the clr sit over night and see if it breaks up anything else.

JJm64123

So after another day of draining water and the clr out of the heater core I actually had heat coming out for about 5 minutes and than it stopped. I have clr sitting in it again over night. But when I flush it out it seems to flow freely and clear! I hope this is ball a waste of time.

turbo510

You are evidently bleeding the air out incorrectly- and relying on pressurization won't work. Also, what engine are you working on?

The basics of quickly and successfully purging out the air are as follows, but first: Rule #1 - don't run the engine, that will actually prevent fully filling the system.

Step 1 - release the reservoir from its mounts, disconnect the level sensor connector, then raise the reservoir as high as the hoses allow, and support it there.

Step 2 - fill the reservoir to the top, leave cap off for convenience.

Step 3 - open that bleeder screw, then close when a constant stream of coolant comes out.

Step 4 - pull back that heater hose until the bleeder hole punched in it is clear of the pipe end.

Step 5 - when a constant little coolant stream is emerging from that hole, push the hose back and clamp it. Reconnect the reservoir level sensor, then re-install the reservoir. Adjust the coolant as needed, then put the cap on. Done.

JJm64123

Thank you! I wasn’t sure if not running it would get all the coolant through the engine especially without the thermostat open! And you are right I was trying to run it because I thought the circulating of fluid would help but I guess I was wrong. I will do what you said now. Hopefully that works!!! Thanks!

JJm64123

So thank you all for your help. After multiple flushes the heat actually works! So now onto my next problem. I have yet to see the cooling fan turn on, but the temp gauge in the dash doesn't go higher than half way. I brought the car a local shop to try to scan the computer and of course the scanner seemed to either freeze after like 20 minutes or he just gave up and unplugged it before it finished. Right before he unplugged it was at 13/16 modules checked and found 26 faults! I don't know if he was just giving me the brush off, but he thinks that the car is overheating and says that i should be seeing water circulating through the overflow tank. So right away he said i need a new water pump. Now do you guys think i should change it out? Or could it be something else i should check that maybe is restricting the water flow through the car? Coolant temp sensor? heater control valve? Idunno im at a loss and i feel like lots of money is going to be dumped soon because of this.

turbo510

The electric cooling fan won't come on if the mechanical one is keeping the radiator cool enough. Also, if you turn AC on, the electric fan should run, which is an easy test to be sure it will function if needed. Finally, your temperature "gauge" going to the mid-point means that the coolant temperature is within the correct range, and not overheating. I refer to the temp indicator as "gauge" because it really isn't; the needle will be straight up over a considerable coolant temp range, which is considered normal.

What your mechanic refers to as the 'overflow tank' must be the reservoir, and you shouldn't expect there to be coolant flowing through that, once the system is filled and the temperature stabilized.

If you intend to keep this car, or any other Audi/VW, I would suggest getting a scan tool such as the VCDS "Enthusiast" from Ross-Tech, $200 which will prove to be well-spent money.