Thermostat position and lack of hot heating

[Martynf]

Wanted to throw this past you guys and see what you think....

I know Greg posted a little while back his heating wasn't getting hot, but he had got all the air out of the system. And at about the same time there were a few posts about the position of the thermostat in its housing. I.E by the book, Audi say the stat has to be in 'X' position.

Here's what has spurned this post:

Now winter is here and its time to defrost the inside of the windscreen in the cold mornings, I've noticied that my heating system is hardly working at all on mine, UNTIL the thermostat opens!!

Here's what happens, or doesn't!! start engine, turn heating to high (AC off) and I can drive for a long time with still only COLD air blowing through the system. I really only noticed this when I started the car and got straight out onto the motorway. I'd been driving for about 40 miles non stop @ motorway speeds and the heating was still stone cold even though the engine water temp was about 80 indicated. I start to think must have an air lock in the system, then I pull off the motorway onto normal roads.

As soon as I stop in a queue of traffic, the engine water temp rises to 90 the stat opens, the fan kicks and low and behold...... lots of hot air comes through the heating system???!!!

It seems like as soon as the stat opens, only THEN will hot air come through the heating system??????????

This has got me suspecting the position of the stat may be important?? when I fitted mine way back in summer, the 'bar' or 'strap' of the stat was in a 10 past 7 position, not in the position the 'book' says (which we found out later!)

The water hoses that feed the heater matrix in the car, one comes off the head, the other hose goes to the water pipe that is feed directly by the..... THERMOSTAT!!! Maybe the stat has to be in a certain position so that hot water from the block is pumped past the stat into the heating system and then back to the engine via the head?

Don't know if this is right or not, but it sure is a coincidence!!!

My heating only gets hot when the stat is open??

The stat is there so that when the engine temp reaches 87, it opens and lets the hot engine water from the block circulate through the rads to cool it before its returned to the cylinder head via the branched manifold.

So either the stat position is critical, or.... I have a blockage somewhere between the stat housing and half way down the metal water pipe that feeds the matrix. I say only half way down this metal pipe as just before the end of this pipe, the water hose from the afterun pump joins it. The afterrun pump is fed from the main rad, so when the stat is open, hot water goes into the rads, and then can go from the rad, through the afterrun pump, then into the metal pipe that feeds the matrix.....

Weird..... I don't have air in the system, or if I do it work come out, I've vented the system at the bleed screw in the hose, the bleed screw in the rad and also 'lifted' the top hose a little off the rad to left air escape that way. Still no joy....

It can only be a blockage at the beginning of the metal pipe, or the stat position DOES matter!!

Any thoughts anyone???
Greg did you ever sort out your heating?

Martyn

[Glen Chamberlain]

For give me Martyn but heads still a bit mashed from last night!

The stat must be open or slightly surley cos 40 miles on the m way with the stat closes surly would cause it to over heat? I know they run cooler on the mway cos of all the air but i had a stat stick closed on my 1.8 80 MY89 and that boiled on the Mway? Sure its, dare i say it ! not a dodgy stat?

When i fitted my stat a month or so back i recalled some one mentioning a tiny air hole in the stat maybe to help it bleed? Well mine didn't have such a hole? I put mine back any old way (cos i for got how it came out) and my car strts blowing warm in minutes! I mean really quickly!! I just put it down to the turbo being water cooled providig heat quickly? Ill read your post again and maybe then try and give some positive comments not all this crap tham iam still waffling on about! Thats what my head feels like!

[Mikes2]

Thermostat should be vertical with the arrow pointing downwards.

[audiman]

Martyn, i have my stat in an unknown position and that works fine! Sounds like a dodgy stat Did you use a genuine one?

If you had a blockage then it wouldnt just clear itself. If you had an air lock, then it would have boiled up by now, you did that job a long time ago now.

I had a stat that only lasted about 4 months that i bought from GSF, used another one and that is fine. Warms up lovely!

HTH m8

[Graham]

I have had mine changed a few days ago and it warms up within minutes, and the stat went in any position as there was no bleed hole in it.
Graham

[A6 AVANT]

When I had my old coupe 83 1.9 WN I had heater problems and found the stat had a rubber seal around the valve and this had perished causing continuous flow. position didn't matter. I recently did the head on Beeties car (3B) and replaced the stat as well and didn't make any particular note on the position and his seems ok. Some stats don't have a bleed toggles on them but do have a little "v" in the housing where the valve is. We sometimes drill a tiny hole in the face of the face of the face of the stat which aids bleeding and helps to keep engine temp down by a couple of degrees but still gives a good heater. Also make sure your auxillary water pump is operating ok and it hasn't seized.
Hope this is of some use.

[Martynf]

Thanks for all the replies it's all pointing towards having to take the stat out methinks and see what gives... time to chuck it in a bucket of hot water.

What a nice job it is too :-)) I bought this stat from Tom Cockings Motor Spares so it should be ok??

Many thanks!!
Martyn

[audiman]

Oi, bar steward! Wheres those bits Did my mate get in contact with you about that ECU for an S3, its the same one who is having that pump for his Ibiza? We are doing a big turbo conversion on it, should be fun when done!! 340bhp in a hatchback heap!!

Anyways, sounds like a duff stat mate. Claim under Audis warranty! Just means that a dealer will have to work on it :O

[Michel]

Please excuse my technical ignorance but is the coolant level at max?

I had exactly the same problem, no heat until the car was over 90 on the guage, this is sitting in traffic for about 15mins with nothing but ice coming out.

Got home and looked and looked at the water level. DOh its low.

Filled it up the next day and hey presto, heat from start up.

I'm sure you have checke dit but you never know.

[AbsS2]

I had the same problem. Topped up the coolant and hey presto! And my stat seems to be fully open. need to sort it out.