Hello all
I'm new to this forum so forgive me if i posted this in the wrong place. I have a 2004 Audi A4 quattro base sedan 1.8LT I've been having heat troubles ever since winter set in here in ohio. I did have a small coolant leak but because of the belly pan i couldn't find where it was coming from. It was collecting in the pan and then dripping out when it got full. I took it to my mechanic and he said i needed a thermostat. I bought one and had it installed. Still no heat. He then flushed the entire cooling system including heater core. Got a bit of heat after that. The odd thing is that when running down the highway at 60-70 mph and cranking at least 5000 rpms i have great heat. BUT the minute you let off the throttle the heat goes cold. After the thermostat replacement i was told that it was the source of my leak. However my coolant light has come on 3 times since the repair (which was only 2 months ago) telling me i'm low on coolant. I have filled the reservoir 3 times now and the warning light is on again. Any ideas where my coolant could be going (No leaks found on ground and belly pan has been removed to look for leaks which are non existent) and why no heat unless traveling at high rpms/mph? Any help would be GREATLY APPRECIATED! Thanks

 

When is the last time the timeing belt and water pump were replaced? High RPM heat only sounds like water pump is weak to me. Same problem I have right now. Is your mechanic Audi/VW knowledgeable?

As far as low coolant I would check the coolant flange as this is a typical leak location and you will not see coolant drip until it is really bad. The drip falls right on to the exhaust and all you see is desidue.

Other possibility is worst case, that would be head gasket. Same symptoms, losing coolant and lack of heat.

First check the flange, passenger side at the firewall. Cheap part, POS to change in tight location.

Good luck!

 

u should also check the hoses near the firewall. There are two near the battery. They should both be hot. If one is not and the other is u might still have a clogg somewhere. U can also burp your system. LEt the car heat up to runing temp. TUrn the car off and open the coolant tank slowly. IT will gurggle. LEt it burp for a little bit. SCrew the cap back in and turn the car on. REpeat the process and see if that changes anything. Ohh and you will also need new coolant as some of it will leak out. Or u can use distilled water! goodluck and let us know how things go.

 

Hi all. Thanks for all the replies.
To answer your questions: Yes my mechanic mainly only works on German made cars. EX BMW Audi Mercedes, VW etc... His shop is called Euro car specialties inc. He is very knowledgeable. I had a coolant leak that was actually coming from a bad t-stat. He replaced the stat, flushed the system including the heater core, and was confident that that would fix my problem. And for a while it did. But even after the stat change and flush i still only had luke warm air at an idle or low rpms. But it was better than the ice cold air it used to blow. I don't know when the timing belt or water pump was changed if ever. I just got the car in June of 2012. It only had 98000 miles on it but i know that is usually about the time when the timing belt should be replaced according to the maintenance section or the owners manual. This may sound like a dumb question but what does the timing belt have to do with the heat or lack of? As far as "Burping the system I've done it several times when i had to add coolant. I even put the front of the car up on ramps thinking that if there was an air pocket it would travel to the highest point and then i could get rid of it. Needless to say that did not work. I will check the hoses tomorrow. I really hope it's not a blown head gasket. That would SUCK and cost me a small fortune to get fixed. My mechanic did ask me if i ever put any type of additives or stop leak in the coolant system as he said it was pretty "gummed up with a type of brown sludge. I never did but the previous owner may have. I was also told that Audi takes a particular spec of coolant so that it doesn't clog or gum up the system. I've never heard of this or seen any special coolant specifically designed for an Audi 1.8LT. Anyone ever heard of this or know anything about it? I did find a link about the rear flange causing coolant leaks DIY: B6 A4 - Rear Coolant Flange Change. Even gives pics and step by step instructions on how to change. I just hate to spend the time and money if it's not the problem. Is there anyway to know for sure without changing it? And if it was leaking would that make me loose heat? I do agree with it drying/burning on the exhaust because i can smell the coolant, so that does make sense that the rear flange may be the cause of my loss of coolant from time to time. Thanks for your help. It's GREATLY APPRECIATED!

 

First off, you can read my story related to stop leak and heater problems on my 98 2.8 at this link....also has pictures of what stop leak does to a heater core IN AN AUDI....if brown sludge came out, I'm going to GUESS that stop leak was used, I had GREY sludge come out of mine.....took me over two years diagnosing this.....

https://www.audiforums.com/forum/b5-...-story-192626/

Now, on to my 2 cents...

Since you can SMELL the coolant, I'm going to side on the coolant flange part as the cause of the leak...but, to be sure, there is a tester out there for head gasket leaks that works great...my buddy has one and it has two chambers and is pretty much always accurate...it's called the UVIEW 560000 Combustion Leak Tester...not too spendy and I think any professional mechanic should have one....last audi that I saw with mysteriously loosing coolant, was leaking into the exhaust and you didn't smell it...oil was clean etc...

The two hoses Pa4ul is talking about are on the center of your firewall when standing in front of the car...there may be a shroud/cover on them...behind the shroud/cover are two hoses, the one on the right is the in-let side TO the heater core FROM the coolant flange, the hose on the left is the OUTLET hose (it also has a pin hole in it to bleed the system)...so, when your car is warmed up, shroud off, feel the right hose, if it's hot then your flow TO the heater core is fine, if the left one is cool or luke warm....your heater core is clogged and you can try BACK flushing it, many DIY on the web and in this forum for that....IF both are the SAME HOT temperature, your core is fine, but you have air in the system somewhere...and IF you have a leak, well, more air is being sucked into the system as the engine runs.......the highest point in your AUDI for the cooling system is your HEATER CORE.....

As far as bleeding the air out of a heater core, I have found that reverse filling it via the heater core works for me....when you read my other post, you'll see what I mean...

IF your car is NOT overheating, temp gauge in middle etc...your water pump AND thermostat should be working fine.....timing belts on the 1.8 are NOT as spendy as the 2.8....and NOT as difficult...you should see if you can find out if it was done....since if it BREAKS while driving....VERY BAD!

Hope that helps,

Marky

 

Marky
Thank you sooo much for these valuable tips. I will most definitely try these to see if it fixes my problem. i will also check with my mechanic and have him test the head gasket. I really hope that is not the problem as that can cost a small fortune to fix. I will be getting the timing belt replaced just to be safe but I was wondering what the timing belt has to do with the heat problem. What's your take on this?
Thanks again for your help.

 

you seem to be stuck on the timing belt probably because you are a new Audi owner....we all ask that because generally on any audi, the timing belt, water pump and thermostat come as a kit and are all done at the same time, so by asking that, we are asking if the water pump and thermostat are/were done as well AS the timing belt.....although on a 1.8, you can do the thermostat and water pump without replacing the timing belt, unlike on a V6 2.8 where the thermostat is behind the belt and the water pump....but without a timing belt, the engine doesn't run...so there would be no heat anyway....

 

LMAO!!! Yes you are right Marky Marc! Definitely no heat or running engine without timing belt. LOL! I just had the stat replaced. No water pump or T-Belt. However that will be my next invest ment into this car. As i said before i read the maintenance section of the manual and it's due for a new belt. I just wish there was a way to test the W pump and have it replaced also if it is failing. I just can't afford to throw money into parts that are working at the moment, but you may be right it could not be working at full capacity which is causing my heat problems. If my mechanic will cut me a break on the labor I just may do it to be safe, and see how it affects my heat problem.

 

It's going to be anywhere from $600-$1200 depending on who does it and where you are. Just have them all done-tbelt, water pump and thermostat...

Here's a photo DIY from ECSTuning-it will give you an idea of the time it takes...
http://bd8ba3c866c8cbc330ab-7b26c6f3...ingBeltDIY.pdf

I'd check the head gadget 1st....

 

All good comments above. My original question about timing belt and water pump was because those are usually always done together. At 98k I would guess it has not been done unless the previous owner specifically said it was. I was in the same boat with mine. Bought at 89k and no paperwork to show it had been done.

As far as the coolant flange my guess is you will find it to be leaking. They are really a common problem. I did mine two years ago and had to do it again this past spring. Granted that was 45k miles but still. Check ECS tuning. I just saw a coolant flange kit that includes the G12 coolant for audi/vw. That's the special pink stuff. With the system not being sealed up it will not pressurize properly and that alone can give you bad flow and lack of heat. Add that to an aged waterpump and you get minimal heat.

I just went through all of this just recently. Spent an entire weekend trying to diagnose a lack of heat. flushed heater core, back filled heater core to make sure it was filled. I'm getting some heat, but just not enough flow through the system to keep up with single digit temps. Unfortunately there really isn't a good waterpump test, just solid diagnosis.

So I'm waiting for a chance to tackle my timing belt and water pump job as it is due for it anyway.

A good kit from ECS or Blauparts will run you about $220-$260. Blauparts just had a nice sale this past weekend. If your mechanic will let you bring him the parts you might be able to get it done for $400-$700 in labor as it is a tedious procedure. My local shop lets me bring my parts and he works for cash and gives me a deal. Maybe you can do the same. Can't hurt to ask.

Keep us posted!