fabf2

I have a 2001.5 A4 1.5T Quattro bought in 2001.5.
This fall the heater has not been very warm. In November I took the car to the dealer complaining that sometimes there was heat and sometimes not (or very little). Their solution was to flush the cooling system. Seemed to help at the time, but then it was hot, not hot, hot. Mostly not hot.

I took it in a second time and they suggested the heater core should be replaced. Expensive. I chose to be cool, cold actually.

Today was -14C and windy. Bloudy Cold!!! I noticed that there was more heat when the engine was reved, and under load. I also use the "magic codes" on the radio to look at water temperature which was for the most part normal at 92C except when I was idling where it went "up" to about 95C.

Might I have a problem with my water pump? The idea occurres to me since I had the pump replaced at about 90,000km when the timing belt was changed. Also the thermostat. Could it be starting to fail??

Do my symptoms sound like a waterpump or a plugged heater core??

Does anyone know of a recall due to waterpump issues?

The car has 130,000km on the clock and otherwise looks and runs like a dream.

I intend to sell this beauty in the spring because I have no confidence the dealer can diagnose and repair these age related mechanical issues which recently have become more common. (I also have concerns about the airflow control dampers)

Please let me know your thoughts and comments.
Barry

weaselciuy

water pump ..it fails to push water trough the circuit thus the heater core gets colder; i bet you get hot air at start (after engine warms up) and keeps getting colder as you drive.

If core was plugged you would get same air all the time untill you get none.

turbo510

A non-working water pump has more drastic symptoms than a cold heater! Clogged heater cores are common. Start by feeling both heater hoses at the firewall by the battery. If BOTH feel hot (after the engine is up to temperature) then there is flow through the core. If the one on the left feels cooler, that indicates bad heater core flow. If that's the case, I'd confirm that by disconnecting both hoses (engine cold this time) and fitting a length of hose to one of the firewall heater pipes, the other hose end clean enough for you to blow into. Lung power should easily force coolant and then air out of the other pipe easily. If you determine the core is clogged, the next step is to use a major-brand cooling system cleaner in the heater core.

MTykhnenko

Flush it out. Use a weak pressure washer (KEYWORD IS WEAK or you'll rip everything to kingdom come), or get one of those "heater flushers". I'd just replace it. Although it is a 4 hour job to JUST get to it.

weaselciuy

Using heater flushers wont help you in the long run, lots of people did that and in several months had to change core + other parts of plastic that came in contact with the coolant+ flushed additive.

You cant know what components those aditives have that dont attack plastic or other engine components, some people destroyed their temp. sensors, others flanges; remember the heater cores plugs are of plastic also, that`s where they go bad when they leak. If both hoses are at same temperature, then you either replace the core all together or check if water pump is working 20% only, maybe some of its pallets broke loose.

I would not put anything in the car except gas, oil and distilled water+g12 coolant.

I dont get why the core would get clogged with coolant? That does not make any sense. Coolant does not get solid in time, except if u used some other aditives. Water also does not get solid unless there was no coolant in it , and there`s no way dust or other stuff that can block the core would get inside the cooling circuit.

Anyway your decision. Try removing the whole coolang from engine and replace with new one, see if any chunks of blockage come out this way.

dm.A4.B5

I agree with everything but the line above. When I flushed the heater core a few months ago I had the waste water/coolant dump into a bucket. I pushed atleast 20 gallons of water through the heater core.

After finishing up, I checked the bucket and the bottom of the bucket was covered with a thin layer of particulates. Basically it all looked like sand, what it was, was rust.

5v/cyl

Flush the heater core with some CLR or Limeaway. Just did this to my Allroad, which had weak heat, and it fixed everything. Nice and hot air now.

Backflush the core with clean water, blow all the water out, then pour in a mix of CLR and water. Let sit for 15 minutes then repeat. Finish off by flushing out good with clean water, blow water out, then reinstall hoses and bleed the air out of the heater core. Should be good to go and hot air again.

MTykhnenko

Its quite common for heater cores to be plugged up. Rust, water impurities, and simply any sort of dirt that gets in when topping it up.

weaselciuy

I flushed my 3 year old coolant and it looked like new, i had to cause i changed the thermostat. It had the same reddish color but no weird stuff in it.

Using distilled water + g12 coolant will not make the engine block or other metal parts rust.

If you used tap water + coolant and God knows what other aditives of course it rusted and stuff started to clog.

As a test, try buying the cheapest "gas additive" (that sais it will clean the injectors, lower mpg bla bla bla) pour it in something and throw in it a metal piece of anything, leave 1 week then inspect it again. Also throw in some plastic, see how they look in 1 week. Pun in some wiring in also. Add to that some pozitive and negative energy and watch how they corrode in minutes, making green filth where the minus(-) wire leaves the container that holds it.

If i were in power i would ban all additives and stuff, all ruin cars. If they were that good, dealerships would use them each 15.000miles or whatever when inspection time is. Of course they DON`T.

As i said, cars must take in ONLY: Distilled water, Oil (engine+gearbox), Gas, washer liquid and G12 Coolant (the simple one not that crap with other super amazing stuff that make the car NOT overheat haha).

Hell i forgot of bake fluid and servo oil
Anyway you guys do what you want, i`m just throwing in my 2 cents.

dm.A4.B5

Rust will form as long as H2O and metal is present. True that additives in the coolant inhibit this but it is not a silver bullet. As for distilled water, it still has a free floating ions (not nearly as much as tap water or salt water) but still enough to allow rust to form, albeit slowly. You're better off using deionized water which is free of free floating ions. And no they are not the same, similar, not the same.

I just use tap. First flush took 10 years to happen.