B6 coolant issues ( what a surprise....)

[ongster]

Hi All ,
I have an 04 A4 1.8t b6 sline which I love.
My problems are these.....when the car is fully hot at 90d I don't get hot air in the cabin , if anything it's a little more than warm. Although when the car is out on the road the air gets 'warmer'.
In the engine bay the bottom hose that goes to the t stat stays cold , the top hose that goes through the bulk head to the heater gets a little warm but the hose below it gets hot.
I do have a small leak at the back of the engine block that I am sure is the coolant flange.
My ques is , fellow diyers & those of experience , which problem is the most likely.....as I will only be able to change one at a time at any given weekend........
So......
1: coolant flange
2:t stat
3:water pump
.....any other suggestions are more than welcome as over expenditure would be an issue :o:o:o
I have tried bleeding the system & blew out the top heater matrix pipe as I suspected a blockage where it runs into the metal pipe that feeds from the t stat......the reason for this was that metal pipe gets hot (it also accepts the feed from around the oil filter) and as previously mentiones the rubber part was hardly warm.
Again any thoughts & or suggestions are most welcome & appreciated.
Best Regards Andy

[Google44]

Your heater matrix seems blocked. There should be two pipes going in matrix from engine bay. They should be of the same temperature. If not I would disconnect both. Get high pressure of water on one and make sure it comes out on the other. If that fails you will have to replace it

[ongster]

Thanks Google 44......in your opinion would this problem make the large bottom hose that goes into the stat stay cool?

[rhencullen1989]

Hi, does your temp gauge in the car get to 90 degrees in a couple of miles and stay there, if so i doubt you have an issue with either your water pump or your thermostat. Are your servo flaps working correctly for the hot/cold air distribution, you can remove the glove box (5 min job) and have a look at the servo's as you tinker with the air con temp controls, you should see things moving. My mates B6 had a leak from the rear of the engine which turned out to be the plastic housing that the temp sendor is clipped into, a bit of a nasty job to replace as its so tight in there, although i would check your seal around the temp sendor first.

[ongster]

Hi There All, I'd like to firstly thank everyone who contributed towards my thread. I'd also like to explain my outcome so that peeps can benefit from my experience.
So after the issues stated above I decided to change the ect at the back of the block. As my wife uses the car it was only when she started getting cold that she thought to mention to me that the dashboard temp gauge kept dropping down to nothing , as though if was 'off'. So with that changed there was a glimmer of 'warmer' air now & again in the cabin. As I was following the complicated & lengthy bleeding procedure I was squeezing the bottom hose (with the engine off) & heard a air leak towards the ect......coolant flange !!!!!
So with the car having done 110,000 miles & wanting to check the water pump fins I also ordered a thermostat as well as the flange.
I used the various online fitting guides for both , which I must thank the contributors for as they proved invaluable....flange absolute PITA....stat not so bad.
Tips:- make sure you have a variety of hose & pipe clamps as the factory ones that you must remove are a one trick pony. A miners lamp attached to your head will probably benefit as you won't have a spare hand (I asked my son to hold a torch but sent him back inside as there was to much swearing going on) , for the stat make sure you don't drop the bolts near the housing that attach it to the block , there is a cavern of metal just below the stat & the bolts easily drop in there never to return. If you've bought the whole kit it should come with new bolts but a magnetic socket would be wise.
As with the bleeding I seem to be quite lucky. The bleed screw on the top of the metal pipe that runs front to back near the injectors snapped with most of it left inside , so that wasn't coming out in a hurry. Took expansion tank off & tilted it upwards with lid off so that fluid was higher then any other point in the system. The car was now running but again wasn't getting hot inside the cabin. Felt both hoses that go to heater matrix through the firewall to find no heat there. Took upper pipe off , no water. Took lower pipe off to find some water coming through so thought I'd fill up the matrix by pushing bottom hose onto top fitting until water came out bottom fitting , put thumb over with a little gap at top to allow air out until there was water there & popped bottom hose back to where it should be. Let matrix fill up then did the same with the top hose , just holding it on there with a little gap to allow air out then as more water appeared I pushed it on. Carried on pumping top rad hose & bottom hose that runs to stat & the whole system burped itself about 5 times , this took about 90mins. But I can now say the cabin is toasty hot after refitting tank & cap & with fingers crossed it might stay that way.
Once again thanks so much to everyone who contributes to these forums , the ********hips must hate them but then I blame the manufacturer in the first place for making the cars so damn difficult to work on , fitting important parts made from inferior materials & charging the earth for am hourly rate to fix them.
Hoorar the free world......:biglaugh: