Hot Air Issues?

[Ronniebiggs]

Just to give a bit of an overview I have a water leak somewhere on my car which I cant locate. I have pressurized the system and looked for it and I cant locate it. Its not the head gasket and the only give away is the small smell every so often of coolant when you put your heater fans on. Usually when put on 1st thing.

Anyway. On a coupld of occasions now my blowers have been blowing cold air and I have to rev the engine or get the turbo to come in and then you can feel hot air. This happened today with the difference of the temperature gauge shot up to nearly 110C then straight back down to 90 and then you could feel the hot air. But drive off boost for a while and the air goes cold.

I cant think of anything except I do have to top the water up every couple of weeks and so if its not bleeding the air out then it may be causingt an air lock which is what I think is happening.
Arnt the audis slef bleeding?

Any advice most welcome?

Think my sig says but its an Audi A4 1.8T (163) 2002

Thanks
Andy

 

[iyrix]

I had this same issue, but on a Honda. Take out one of the spark plugs and see if it looks like it's been through the washing machine. It won't use much water at first but when it goes it will be quick!

To me the gasket has gone.

 

[iyrix]

Thinking about it, I'm 90% sure the head gasket has gone.

You might also want to check the water pump and thermostat.

 

[BASS 666]

they are self bleeding mate. i changed my t.belt a while ago when i built it up again i started the car and right away i poured my 2 litres of coolant in and then the water. it bled in 5 mins. today i changed my stat and when built up i poured the coolant and water in without starting the car. what a c..t it took forever to bleed and the heater didnt work for ages but a long drive sorted it. have you had work done lately ?

 

[Ronniebiggs]

No work done lately but I do add water all the time without starting the engine first. I cant imagine it been the head gasket as there is no water in the oil etc. I think the heater matrix is leaking as you can smell coolant when the blowers are first put on. But the strange thing is there is no wet capets I can see etc (Assuming the matrix is inside the car).

Last time I added water was about 3 days ago so its strange how it never happened straight away and instead happened today (as I said I did have this happen once before but that was a while ago)

I dont want to steer peoples thoughts but I have noticed that im getting what I believe to be alot or more than I once had of lag. This could be totally non related and I think its to do with the aftermarket exhaust manifold I put on as I couldnt get some of the nuts on so I left them off which may be drawing air in there. Also the exhaust is blowing.

 

[BASS 666]

there is a water cooled turbo on your car. maybe it has to do with that ? you should get a presure test done..

 

[Ronniebiggs]

Pressure test on the turbo? I need to be quite sure before I go to any garage as cost spirals out of control when you go to garages. Thats why I like to do everything myself. But unfortunatley as this is my ownly car at the moment I cant affod to have it off the road for a day so I cant do pressure test it myself etc.

Im no expert but it still sounds like air blockage to me and maybe a hole in the matrix but I wont know until I get time to have a good look which will be this weekend at earliest

 

[BASS 666]

in work we have a pump that attaches to the water bottle and we pump it untill there is some presure in the system. whiat happens then if there is a leak it pushes the water out of where the leak is and you can also hear it. i cant see a garage charging you too much to do it. its funny your getting lag, and you can smell it aswell. i would get the presure test done mate and look and listen..

 

[iyrix]

Still sounds like water is getting into the chamber. (Could be one reason why you have lag...?) The head gasket can go without water getting into the oil.

Have you got a wet floor?

 

[pj123]

Anyway. On a coupld of occasions now my blowers have been blowing cold air and I have to rev the engine or get the turbo to come in and then you can feel hot air. This happened today with the difference of the temperature gauge shot up to nearly 110C then straight back down to 90 and then you could feel the hot air. But drive off boost for a while and the air goes cold.

If your car get get up to 110 degrees then you will have killed your thermostat so you will need to replace this. Engine should stay bang on 90 degrees whatever you do.

However the reason i think your temp varies is because you may have lost an impeller from your waterpump. When was the WP and timing belt last changed and did they put a metal WP in or is it still one with an original plastic impeller type? When you rev water can then circulate better, pushing the hot water past the coolant temp sensor which may explain the variation in temp...

As far as the leak goes have you checked around the water pump itself. Timing belt casing makes this a little difficult but water pumps are known to leak.

Final word of warning, going over 90 degrees will damage the engine. I would avoid driving it till it is sorted although appreciate that may be a problem.

If you are member of the AA they will diagnose if your water pump has gone. Tell them it overheated and you dont want to drive any further.

 

[BASS 666]

pj123 is right i put a new pump and belt kit in for a guy and he came back 2 wks later with a coolant leak. it was the pump.

 

[Ronniebiggs]

The test I did was as you said with a pump on the coolant tank I we could see or hear nothing.

I havent had the timing belt of water pump changed and im not sure if it has been done from new. The car has just done 100K and I know you need to do the timing belt and I plan on it once my 2nd car is on the road. If the impeller on the water pump was gone then it would do this all the time. My car is now running fine temp as always is sat at 90 degrees and doesnt move.

My issue is why I had the spike in temp which lasted less than 2 seconds so im not worried about damage but I understand that using it at that temp for some time would damage it.

I have had this happen now twice which still makes me think air lock.

Lag might just be me thinking its laggy or it could be the turbo manifold I put on leaking as I never got all the nuts on.

 

[pj123]

Timing belt at 60,000 miles or 5 years. I would urgently sort this if you are on the original. New timing belt and waterpump, both part of the same job.

My impeller gradually broke up over 2 weeks. For 2 weeks when i switched the engine off there was some strange gurgling for a minute or so until it gave up with some faster driving. It is possible as with mine that you have bits of impeller catching in the thermostat as it flows around the system and/ or a half working water pump that is still struggling on.

As you had a spike in indicated temp there is a possibility you do actually just have a dodgy coolant temp sensor. You need to read the fault codes to determine this though. £30 from audi including o ring and clip and is a simple diy job. If you dont already have the update green one it could be worth replacing anyhow, but reading the fault codes is the only way to tell if you are curing the problem.

I think the possibility of an air lock is unlikely as you would be having a more constant problem.

Lag on my 1.8T stemmed from the MAF, after 90k and 11 years of life it was reading half what it should have been. i.e. telling the engine half the air was entering the engine and hence ecu requesting less fuel. They are known to fail over time along with your diverter valve. new MAF £90 and a DV £30. Some people consider these consumable parts! Easy to change both yourself. Again you can check the MAF with VAG COM, should be reading 0.8xBHP of your engine in grams per second.

 

[Ronniebiggs]

Timing belt at 60,000 miles or 5 years. I would urgently sort this if you are on the original. New timing belt and waterpump, both part of the same job.

My impeller gradually broke up over 2 weeks. For 2 weeks when i switched the engine off there was some strange gurgling for a minute or so until it gave up with some faster driving. It is possible as with mine that you have bits of impeller catching in the thermostat as it flows around the system and/ or a half working water pump that is still struggling on.

As you had a spike in indicated temp there is a possibility you do actually just have a dodgy coolant temp sensor. You need to read the fault codes to determine this though. £30 from audi including o ring and clip and is a simple diy job. If you dont already have the update green one it could be worth replacing anyhow, but reading the fault codes is the only way to tell if you are curing the problem.

I think the possibility of an air lock is unlikely as you would be having a more constant problem.

Lag on my 1.8T stemmed from the MAF, after 90k and 11 years of life it was reading half what it should have been. i.e. telling the engine half the air was entering the engine and hence ecu requesting less fuel. They are known to fail over time along with your diverter valve. new MAF £90 and a DV £30. Some people consider these consumable parts! Easy to change both yourself. Again you can check the MAF with VAG COM, should be reading 0.8xBHP of your engine in grams per second.

Thanks. I already have a new DV. I have a forge recirculating DV. I have no ECU light on so there wont be any fault codes to read as there is no fault registering. Water pump is starting to sound more likely as I have a leak I cant locate and it hasnt been replaced to the best of my knowledge.

I would love to just replace all the above parts but I tend to do that and it always usually ends up never been the parts I replace and it costs a fortune. Also I just spend £610 on new tyres and £235 on tax less than a week ago so I could do without any extra cost.

MAF sensor is a possible replace as its doesnt sound that expensive.

 

[pj123]

You can get fault codes without the engine light coming on, depends on the severity level. I recently did a scan on my partners car and it came up with an intermittent fault for the coolant temp sensor, despite there being no indication there was a problem. As they get worse they send wacky signals out and the dash temp display will display the values.

Worth getting a laptop cable for £15 if you dont have one and you can download the basic vagcom to do scans.

My car came back to life when i changed the MAF on my S3, but appreciate all these things add up to be quite expensive. Dont let that timing belt go on too much longer if its original though or it'll be mega bucks.
Paul

 

[pj123]

Try unplugging the MAF and going for a drive to see if it sorts out the lag, then you'll know. When unplugged a default set of values are used....

 

[Ronniebiggs]

Could it just be as simple as a dodgy thermostat?
Just had to fill up the coolant again as I got the low coolant warning again. Took it out and drove about 8 miles and the air was cold until I thrashed it when I was nearly home and the hot air came through. But as I said I got the impression that if I kept driving the air would have gone cold. The engine temp was nice and stable at 90 all the time. Wierd!

 

[iyrix]

Are you losing any power?

 

[pj123]

Holding 90 degrees suggests the thermostat is ok although might be a bit slow hence you saw a quick spike. Higher revs would increase water pump speed and hence flow around the heater matrix. My money is still on the water pump impeller being partly broken up.

Anyone else have a view?

 

[Ronniebiggs]

Well the water in the header is only lasting 3 days now which has got me really worried. I think I found my lag problem. I remember ages ago people taking of an electronic sensor on the accelorator (I think it was that one!) and when it gets only if you rev the engine the revs drop down very slowly instead of straight down. Well when I plant my foot even in neutral the engine takes a few second then revs right up and drops back quite slowly down I thought my engine was going to blow

Could someone confirm this for me as well?

So now back on topic. Im torn between water pump and maybe a leak or possibly a dogy filler cap.

Is it possible that if the header tank top was faulty then the coolant could escape or is it unlikely to be this?
As said previous it sounds like water pump.

 

[iyrix]

is there any excuse pressure building up in the system when you lose fluid?

 

[Ronniebiggs]

Not sure to be honest. As usual if I remove the cap it will bubble over if the engine is up to running temp. But thats normal. Its not lots of pressure just water returning back to the header tank due to expansion.