Cooling System Woe

tux

tux

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Can I call on your collective wisdom and expertise guys?
The radiator crapped out on my 1998 A4 2.4 earlier this week. I have just changed it out, refilled the cooling system (no leaks) and started to bleed it up. After about half an hour I am still not getting hot air through the heater vents, but there is no more air coming out of the expansion tank and it is not overheating.
I put the cap back on and took it for a spin as this sometimes helps. The scary thing is, the higher the revs get, the warmer the air gets, but as soon as the revs die down the air gets cool again. I have my suspicions as to the problem, but want to see what you guys think. I'll keep my theory to myself for now to reduce the chances of looking daft! lol.

All input gratefully accepted. Thanks everyone.
 
knackered waterpump, or thermostat, change thermostat first though its cheaper lol saying that, im not sure where it is on a v6
 
aragorn said:
Did you pull the heater hose back to uncover the little hole to bleed it?
Click to expand...

I wondered if there might be some quirk to bleeding it. Tell me more. Where is this bleed hole you speak of? :)


sam80quattro said:
knackered waterpump, or thermostat, change thermostat first though its cheaper lol saying that, im not sure where it is on a v6
Click to expand...

My initial thought was a fubar waterpump. Timing belts have to come of on the V6 to do waterpump and the thermostat, so it may be time to shell out some cash and get the job lot done.
 
the two heater hoses are next to the battery. One is extra long, and has a hole in it. You pull it back to expose the hole, which lets the air out of the heatercore.

You basically pull it back until the hole is exposed, then fill until water comes out the hole.
 
I had the same prob with mine when adam did a timing belt service...
As Arogorn the wise (with a long grey beard) says pull the hose back to expose the little hole. At the same time put your bliw heater on top temp and full blast. When the system has bled out the air through the vents should get warm. When water starts to pour from the little hole with minimal bubbles push the hose back over the pipe. If its being cantancorous give the largelr pipe in the bay a few squeezes/pumps. That should sort it.
 
Excellent! Thanks gents, I'll give it a go tomorrow. Have to say it was a lot better this arvo, so hoping I may have sorted the worst now.
 
On a bit of a tangent, are timing belts a DIY proposition on the V6? I pretty well versed in the likes of Ford CVH and Pinto stuff but never tackled a twin cam. Any special tools or locking equip needed?
 
Yeah well within DIY limits. If you are going to do it do all the other parts to. Thermostat,waterpump,aux belt,tensioner,pulleys etc etc. I did the rad at the same time too. Well worth doing for complete peace if mind. Good luck!
 
FWIW i've always bled mine without the engine running, and the Audi heater core is "full flow" meaning it doesnt matter what settings the heater controls are at, the water still flows thru the heater core!
 
Thanks guys. Unfortunately the plot has got slightly thickler! Seemed to be bled up OK this morning, went for a 30 mile spin this afternoon and all was fine, but as I pulled back onto the drive at home the low water warning light/beeper came on. Filled with water (approx 2.5 litres) went for anopther drive, similar distance and exactly the same happened again. There is absolutely no sign of any steam etc from the exhaust and no sign of water leaking from anywhere except the overflow/pressure relif drain? outlet right underneath the expansion tank. This seems to weep slightly, but nowhere near enough to drain 2.5 litres of water in under an hour.
Anyone have any possible theories as to what could be happening at all?
Thanks again everyone.
 
If I were you I would remove the undertray and let her idle. I used to put a white sheer under the engine on the driveway and any leaks would be confirmed obviously wherever the sheet was damp/was a damp patch. It takes a while but it might be worth it. At least then you will know the area from where it is leaking out. Then you can start to zero the problem once the general area has been identified.
 
yeah
If no visable loss, no smoke or steam from exhasut, no mayo oil, not many options left. It cant be going to Narnia. LOL
 
Last edited:
No, no steam in the cabin. Its a bit of a mystery.

I have pretty much reached the limit of my mechanical "expertise" now, not to mention time so it has gone into a local garage to let them have a look at it.
Since I am a born pessimist and would have no luck at all if it weren't for the bad luck, I'm kind of expecting them to call me and say the head gasket(s) is/are fubar. Just a bit odd that there is absolutely no excess emissions from the exhaust, or indeed amywhere else that I can see. Ah well, should soon find out now.

Thanks again for all your input guys.
 
I dont think i've ever heard of a gasket failure in all the years i've been around this forum. Even on stupidly tuned S4's and 1.8T's they're very rare.

That probably wont stop a garage telling you its that, and fixing the water leak while the heads are off though ;)
 
The garage is run by an old friend of mine who I think I can trust, so I'm not too worried about that. at the end of the day I'm in ignorance now, so I have to trust someone! :laugh:
Anyhoo, a sniff test shows that at least one HG is indeed dead. They have said "book" time is around 10 hours so have quoted a "rough" £550 for one HG. Obviousley I would get the belts, tensioners. waterpump, thermostat etc done while its apart so that would be extra. That sound reasonable?
 
You've no way of knowing which gasket has failed though, so you'd have to do both regardless...

ETKA says 740mins for both heads, removed and reinstalled.
 
when i did the cambelt on my s4, i didnt bleed it properly afterwards because i didnt know about "the secret hose"

my heater wasnt particularly hot (in the coldest winter too, that sucked) the next night i pulled the heater matrix hose to the bleed position and everything was tip top again after that

did you find the other bleed nipples too?
 
I would get both heads done of course, false economy not to to my mind, although a compression test should highlight which one or if both heads are giving trouble.
The problem I have now is that the car is probably not worth much more than its going to cost to get it fixed, so I have a dilemma. It needs its MOT as well and I suspect there will be a couple of bits and pieces needed. So I am wondering whether it is worth getting it repaired or breaking it for parts to try to recoup some cash or just sell it on as a "project."
 
Alternatively you could buy another engine and just swap it over?

I was in a similar position with the old FWD A4. Engine was seriously gubbed, and it was a lot of money to fix, but i figured that at the end of the day, theres not enough valuable bits on it to make anything from breaking it, and its worth very little if i were to sell it as is, so i baught another engine, replaced the cam belt and clutch and installed it. Probably spent 7-800quid in the end.

Its a bit of a toss up really, i then managed to sell the car for a grand four months later, so i guess the question is could i have got 200quid for it in its broken state. In reality had i been truthful about it, i'd have managed just about that and no more. I could probably have lied thru my teeth and sold it on as a "working car" and made more, but i'd have felt a bit crappy if i'd done that.

I fixed it becuase at the time i was planning on keeping it for another year, and knew the rest of the car was mechanically sound. I couldnt have baught another A4 in as good nick for the amount it cost me to fit the engine, so the engine was the sensible option.
 
Just been looking at replacement engines. They seem to vary wildly in cost, anything from £250 right up to £750. I was thinking if the engine at £250 is any good, then it may be the cheapest option. Maybe £400-£500 to have it fitted? Maybe anpther £150 for belts/waterpump etc while its going in. Not really able to do it myself, I'm not that mechanically astute. Only thing is I am (again!) buying an unknown quantity. I don't know a good engine from a bad one lol.
I guess it may be time to take a leap of faith and just go for it.
thanks for all the advice so far peeps, especially you Aragorn. Really is appreciated.
 
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