Brrrrrrrr.... It's cold in here!

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Over the past few days with the cooler weather it seems that I've uncovered an issue that didn't really present itself during the mild spell but is now apparent.

The issue is as follows;

The engine reaches normal temperature after around 5 or 6 minutes (as per usual) but the heater air is only slightly warm. I first noticed this when I purchased the car a few months ago and at the time I mentioned it to the seller. He revved the car to around 2,000 rpm for about 30 seconds and then the heater was nice and warm and on my drive along the motorway it was nice and toasty inside.

What I have been finding this week whilst sitting in a lot of stop start traffic and just idling for long periods is that the heater air is cool - not cold, but far from being warm. the length of time I'm driving for doesn't seem to make any difference but what does seem to get the heater working is when I hit a nice clear stretch of motorway and the revs increase over a sustained period of time.

Any thoughts on what this could be? I had read somewhere about water pumps on these. there are no other symptoms.

Thanks in advance.

 

[FRANKIE]

Perhaps you could check two things, the fluid level of your coolant and the tension of the belt driving the water pump. I don't know if there could possibly be a pocket or air stuck in the line. Perhaps other members could comment on this. Frankie

 

[TaffZee]

Thermostat, blocked heater matrix/pipe. Try flushing the system with something like this:http://www.ebay.co.uk/itm/Wynns-Pro...574?pt=LH_DefaultDomain_3&hash=item3a8b4ef086

 

[t-tony]

It is not uncommon for plastic Impellers in water pumps to come "loose" on the shaft and then not spin at full speed (slipping) and consequently not pumping the water round the system as it should.
I can't say if this is a known problem with these engines or not, but I'm sure someone will be able to.

Tony.

 

[zedonist]

Missing thermostat? Thermostat stuck open?

 

[Brian4]

Sounds like thermostat failed open

 

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I was just out in the Z again now for a quick 20 mile round trip. What I found was that whilst I was actually driving, the heater was nice and hot - so hot in fact that I could hardly bare it, but...

Whenever I stopped for more than about a minute in traffic, I would feel the air gradually getting cooler and cooler. Once I was driving along again - it would get nice and toasty again.

After the initial few minute warm up (around 5 mins) the temp gauge remained solid on the mid way point. Am I right that if the thermostat was not there or stuck on that the gauge wouldn't get to the mid point at all, or if it did would take a long time and that the temp gauge would fluctuate quite a bit? When I lift the hood and touch the hoses they all feel nice and hot.

If a belt was slipping would I hear it squealing?

I'm sort of thinking water pump but that sounds expensive so I'd rather not think about that too much. If on the other hand it's a heater matrix - is that a dashboard - out job?

I wouldn't be overly concerned but with winter just around the corner it's pretty important that I'm not sitting in the car shivering and wearing gloves, a hat and scarf ;-)

 

[FRANKIE]

I was just out in the Z again now for a quick 20 mile round trip. What I found was that whilst I was actually driving, the heater was nice and hot - so hot in fact that I could hardly bare it, but...

Whenever I stopped for more than about a minute in traffic, I would feel the air gradually getting cooler and cooler. Once I was driving along again - it would get nice and toasty again.

After the initial few minute warm up (around 5 mins) the temp gauge remained solid on the mid way point. Am I right that if the thermostat was not there or stuck on that the gauge wouldn't get to the mid point at all, or if it did would take a long time and that the temp gauge would fluctuate quite a bit? When I lift the hood and touch the hoses they all feel nice and hot.

If a belt was slipping would I hear it squealing?

I'm sort of thinking water pump but that sounds expensive so I'd rather not think about that too much. If on the other hand it's a heater matrix - is that a dashboard - out job?

I wouldn't be overly concerned but with winter just around the corner it's pretty important that I'm not sitting in the car shivering and wearing gloves, a hat and scarf ;-)

Looks like you won't be stopping for anyone or anything. Frankie

 

[FRANKIE]

I was just out in the Z again now for a quick 20 mile round trip. What I found was that whilst I was actually driving, the heater was nice and hot - so hot in fact that I could hardly bare it, but...

Whenever I stopped for more than about a minute in traffic, I would feel the air gradually getting cooler and cooler. Once I was driving along again - it would get nice and toasty again.

After the initial few minute warm up (around 5 mins) the temp gauge remained solid on the mid way point. Am I right that if the thermostat was not there or stuck on that the gauge wouldn't get to the mid point at all, or if it did would take a long time and that the temp gauge would fluctuate quite a bit? When I lift the hood and touch the hoses they all feel nice and hot.

If a belt was slipping would I hear it squealing?

I'm sort of thinking water pump but that sounds expensive so I'd rather not think about that too much. If on the other hand it's a heater matrix - is that a dashboard - out job?

I wouldn't be overly concerned but with winter just around the corner it's pretty important that I'm not sitting in the car shivering and wearing gloves, a hat and scarf ;-)

If the water only circulates at a higher RPM as when driving, it is probably belt adjustment or bad water pump or bad thermostat, assuming your coolent level is correct. I can't think of anything else that would affect it, unless someone else comes up with something. Start with checking the belt. If the thermostat is old, change it, leave the waterpump for last. Frankie

 

[FRANKIE]

I was just out in the Z again now for a quick 20 mile round trip. What I found was that whilst I was actually driving, the heater was nice and hot - so hot in fact that I could hardly bare it, but...

Whenever I stopped for more than about a minute in traffic, I would feel the air gradually getting cooler and cooler. Once I was driving along again - it would get nice and toasty again.

After the initial few minute warm up (around 5 mins) the temp gauge remained solid on the mid way point. Am I right that if the thermostat was not there or stuck on that the gauge wouldn't get to the mid point at all, or if it did would take a long time and that the temp gauge would fluctuate quite a bit? When I lift the hood and touch the hoses they all feel nice and hot.

If a belt was slipping would I hear it squealing?

I'm sort of thinking water pump but that sounds expensive so I'd rather not think about that too much. If on the other hand it's a heater matrix - is that a dashboard - out job?

I wouldn't be overly concerned but with winter just around the corner it's pretty important that I'm not sitting in the car shivering and wearing gloves, a hat and scarf ;-)

I don't know where the heater core is, as I never had a problem with it. If you have to change it, and you have ac, its a bi***. Without ac, its much easier, generally speaking. I had a ford once where the heater core was $30 and the dealership wanted $1100. to install it.

 

[t-tony]

First and cheapest option is to "back flush" the heater matrix. You can do this by disconnecting the heater hoses from the matrix, usually close to the bulkhead and then push a garden hose into/onto one of the connections, turn the tap on and run water through the heater. Do not use full pressure or you may cause leaks, observe the water coming out and run till it become clear. Re-fit the hoses top up with new antifreeze and bleed the air out. Then see what happens.

Tony.

 

[oldcarman]

No need to remove dash to get heater core out.
Disconnect battery negative cable and cover with insulating material
Drain cooling system
Remove heater hose clamps at engine bulkhead. Remove heater hoses from core fittings
Blow low compressed air through core to remove any trapped coolant. Use safety glasses.
Remove trim panel from lower left of instrument panel. Could be right for RHD.
Remove lower knee bolster and any cover panels that may impede access
Press coolant lines together then separate from core.
Remove footwell air outlet retaining screws and remove outer grill.
Remove heater core retaining screws then pull heater core sideways to remove.
Reverse to install. Fill with coolant and bleed.
You may want to check out the heater control valve as coolant is constantly circulated through the heater core except when the temp control valve is set to full cold position. Perhaps it's only opening part way which would give you cooler air when not moving.
HTH JIM

 

[AussieZ3]

I agree with Jim that the problem could be the heater control valve. With the temperature controller at the maximum hot setting the valve should be fully open but if the controller is set at the half way in the red region I understand the valve opens and closes several times a minute to maintain the required temperature. It is possible that the valve may not be fully opening to allow the required flow rate through the heater core. At high speed the flow rate may be reaching the required minimum to provide hot air. -Kith

 

[upstream]

Thanks for the advice and guidance guys. The other day I connected my code reader and selected "live" data. It showed the coolant temp as being at 96 degrees. The temp gauge on the car was right in the centre - where it usually is. then I did a bit of googleing. My understanding is that with the plastic thermostat housing you replace the housing which contains the thermostat. On my car this housing looks in pristine condition. It's not anywhere near as dusty as the rest of the bits under the bonnet and looks as if it has been changed (probably not too long ago).

Another time I started the car from cold and ran it for about ten minutes. The temp gauge was reading in the middle but the air was cool. I removed the cap from the expansion tank and looked inside. I could see that the coolant was being slightly agitated (which I'd expect if the coolant was being pumped around). I then turned the engine off and popped my finger down into the coolant. I did this four or five times and each time I was able to hold my finger in the coolant for around four or five seconds before having to remove it as it was too hot. that would sort of lead me to think that the temp wasn't getting hot enough (poss thermostat) but as the temp gauge in the car reads the correct temp and the live data from my code reader showed 96 degrees on an earlier occasion, I'm unsure what the cause could be.

I'm tempted to have the water pump changed anyway as I have heard that these get worn over time and as I don't have any record of it having been changed it probably wouldn't hurt to do it.

It's just the weirdest thing really. When I'm motoring along the motorway, the ambient temperature is relatively mild or I'm travelling along A roads the heater temp comes up quite nicely but when stuck in traffic or on cooler days (when I need heating the most), it's just cool :-(

 

[zedonist]

Either thermostat stuck open or heater valve not working, only things based on your symptoms described

 

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Either thermostat stuck open or heater valve not working, only things based on your symptoms described

Thanks.

Based on that I'll have to guess at it being the thermostat - despite the fact that the plastic bit looks quite new-ish. I'm assuming that if it were the heater valve (which I think is probably mechanical) on the basis that it works sometimes.

If you were a betting man - which would you put your money on..?

 

[zedonist]

Sorry Andy,

Re-read your post, you say that it gets cooler when sitting in traffic, I was in tesco so only half thinking, if it is getting cooler when in traffic then it points to circulation as the engine speed is slower, this could quite easily be an air lock problem, and the system just needs to be bled, if it has recently had a thermostat as you say, this might be the case, can't hurt to try.

 

[upstream]

Thanks. My understanding is that bleeding is done via that little phillips head plastic screw next to the filler cap on the expansion cap. In my case though, when i first bought the car I found that to be a little loose. When I tried to tighten it by turning clockwise it just seemed to spin and not get tight at all after a few turns. Concerned that it might suddenly just fall off or something leaving coolant able to run out, I left it as is.

I guess I need to bite the bullet and turn it anticlockwise to see if it loosens and comes out as it should - or not!

;-)

 

[upstream]

Is it possible to bleed the system without using that bleed screw?

 

[oldcarman]

It has now gotten to the point where it's pretty cool during the day and requires the soft top to be used. Also my rear window is out pending replacing the top. Even so, with my heater and fan on full I get very hot air filling the cabin area whether idling or mobile. Therefore, I would again suggest checking the control valve. That said, how about running several diagnostics with temp checks instead of going by just the one reading and see if that is fluctuating which could very well be a thermostat problem. HTH JIM