2001 Audi A6 2.7T APB engine. So today as I was driving home I noticed that the coolant heat level was above normal, I stopped, added water and it just poured out from under the passenger side of the radiator. Got home slowly (letting car cool here and there) and slid under the car to find the lower coolant hose was OFF. How the hell is that possible, clip is gone (and I'm 100% sure I put it in correctly 100%). So I made a temporary one out of coat hanger and put the home made one on the upper coolant hose and the original one on the lower coolant hose (since the upper one is MUCH easier to replace when I get the new one). So i began adding coolant, 6 liters and nothing came out from the hole in the hose where you bleed it, finally at like 7 liters it started coming out. So I cleaned up and decided to go for a test drive. No heat. ughh, for some reason it didn't bleed right??? Nope, I decided to take a garden water hose and force water to run through the hole system. Finally I had heat. Time for another test drive, heat was fine for 2 minutes and then no heat again and coolant temp rising, what the eff.... So I bleed it all again. Another test drive, heat is on and off randomly, when the heat is on the coolant temps go down, when it starts blowing cold the coolant temps rise until I have to pull over and let the car cool. What the hell is going on? Please help me out here.. I'm about to change the coolant temp sensor just because I have an extra one... but seriously something is weird, help.

UPDATE: It was the water pump, impeller completely off the shaft. I guess sometimes it got caught by the shaft but as soon as I drove it would slip off and on randomly, until it didn't catch at all anymore (well I didn't want to test it that much because what if the impeller became crooked and caused the shaft to lock up, engine BOOOM)

 

Fill the system with coolant and release air from the heater core upper hose by sliding it back until the small hole in the hose lets only coolant out with the engine running. Completely top off the coolant in the tank then cap it. Then run the engine around 2K RPMs until the engine is completely hot and then shut off the car. If there is an air pocket, it won't release until the engine gets hot enough for thermostat to open. You should then see the coolant level in the tank drop after about 30 minutes. If the tank is really low, wait until there engine has cooled off enough to add more coolant. It should be fine after that. If not, I would suspect something is wrong in the cooling system.

 

with the engine running? the service manual doesnt say that the engine should be on, it doesn't say it should be off either. the 2 times I had my coolant empty I just ran water with a garden hose through the whole system with the engine off, I put the garden hose into the coolant reservior (kept it sealed with my hand and forced water in until it came out the small hole in the heater hose. I think I'm going to flush everything out again and try again, after I change the coolant temp sensor. i have a feeling the thermostat is not opening anymore or the water pump stopped. but, when the engine is on and I remove the cap from the reservior the coolant starts flowing out... that isn't normal right?

 

ughhh, no change. i changed the coolant temp sensor and flushed the whole system again with a garden hose. there is no way there is any air in the system. I ran the water until it was flying out the of the hole in the heater hose and then slowed the flow down and quickly pushed the hose back in. I was running the car till warm, air blows cold when the ac is set on hi/hi, started to overheat again, turned it off. I also tried to bleed the system with the engine on, water just comes out of the hole in the heater hose and from the allen/torque bolt/screw in the front of the engine. when the engine is running and you take off the coolant reservior cap off, water starts rising and coming out...

is this a water pump/thermostat issue now? how come there is no heat inside??? shouldn't there be heat even if the thermostat is stuck?

 

Yes, you should get some heat once the engine is hot even with the thermostat closed. Best document on this is from the factory study guide - get it at http://www.mediafire.com/?1a6kznk5c5on572 Look at pages 8 & 9.

The thermostat only bypasses part of the flow when the engine is cold, so there is always some circulation through the heater core and the radiator when the engine is running.

You could also check to see if the coolant in the expansion tank (reservoir) and/or the radiator is hot when the engine temp shows normal (check before it overheats...) If not, there's no circulation from the water pump.

The combo of it overheating and the lack of circulation through the heater core kinda says that in running it dry you may have killed the water pump. Only kinda good news there would be if the mileage is close to needing the timing belt done too...

Jim

 

yea, i really think its the water pump. sometimes it spins sometimes it doesn't. does that make sense? does that happen?

i've been sitting in the car for like 30 minutes. heat goes on and off. mostly once at idle and the heat is on it will stay on for like 5 minutes and then shut off. then it will start overheating and i'd shut the engine off, then I'd put it back on, heat is back on until it stops again and starts overheating again. if the heat is on and i begin to drive around the block it goes off right away and starts overheating...

 

I'd stop driving it until you figure out what you want to do - overheating can warp heads and cause other things to fail. Right now you probably only have the water pump gone, but every time you run it you take a chance of killing something else...

Jim

 

i'm due for a timing belt job, i actually purchased the car at 100k miles and it has 170k now, and I do not know if it ever had a timing belt done, but when i had the engine out the timing belt looked brand spankin new. ordered everything for the timing belt job, from blauparts, with the racing timing belt, tool kit, even got an extra cam locking bar on ebay, just in case it takes me longer to do the job... hopefully it is the water pump and life will be good after i finish it.

i really really wanted to get the kit from ecstuning but the instructions blauparts includes and the tool kit made me decide to order from blauparts.... i know ecs would have higher quality parts, but at least on this timing belt job I want as many instructions as i can get, (my first timing belt job on any car) AND THEN I'LL FINALLY GET A CHIP!!! YAY

 

Then I'd do the timing belt and water pump right now - if the TB has at least 70K miles on it (on the off chance it was done just before you bought the car) it's time. If it was never done, you've been amazingly lucky!
Jim

 

Well, pay attention when yo remove the old water pump. If you can't find anything wrong with the impeller, like it's spinning on the shaft or something, chances are when you put it back together it will do the same thing. Pay attention to the thermostat...wouldn't hurt to test the new thermostat in hot water...make sure it opens/closes.