Technical Thermostat - Heating problem - No hot air from Blowers

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Technical Thermostat - Heating problem - No hot air from Blowers

RobertWH

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Yesterday when driving my (Bravo 80 1.2 16v) home from work, stuck at some traffic lights and noticed my temperature gauge start rising quite quickly. I thought if the car was over heating to try and put the blowers on hot to cool the engine off. I did this but noticed no hot air was coming out. I then got onto the motorway and the temperature gauge dropped down to normal, then driving back into town it started to creep back into the red. When I parked up at home it was just off red and the radiator fan kicked in.

I left it for a while and let the engine cool before checking the coolant, this appeared to be a little low but not below the minium. I checked the oil, which appeared to be fine and couldn't see any evidence on white residue to suggest head gasket problems. I topped the coolant up with some water to the maximum. I drove the car to work this morning fine, didn't appear to be over heat temperature gauge stayed in the middle. Still no hot air from the blowers though. Checked the coolant again, it appeared to be fine. Although I didn't get stuck in any heavy traffic on the way in, which appears to be causing the problem. I did notice though when I went back to the car about 3 hours later and checked the temperature gauge it was still at around a quarter. The radiator fan doesn't appear to be kicking in, well at least until it gets very hot.

Any suggestions to what I can check, I've had a read around and people seem to suggest checking for air locks first. How would I go about this? How do I bleed the radiator? is the thermostat gone? One thing I did notice a few weeks ago when pulling away it almost sounded like I had some water in the dash. It sounded like some water was running around. Another thing to add not sure if this is linked but I did notice when accelerating it will sometimes stutter. How expensive is this likely to be?

Any advice appreciated, thanks Rob
 
At the back of the engine bay to the right hand side you will see the two heater pipes that go through to the heater, there is a bleed screw on both of these, top the water up and unscrew one at a time till water comes out.

with the engine hot check the top rad hose (carfull it should be hot) then check the bottom rad hose (again carfull this to should be hot) if the bottom one is cold then the chances are the thermostat is not working (this confuses me too as the thremostat is at the engine end of the top hose)

Hope this helps.
 
At the back of the engine bay to the right hand side you will see the two heater pipes that go through to the heater, there is a bleed screw on both of these, top the water up and unscrew one at a time till water comes out.

with the engine hot check the top rad hose (carfull it should be hot) then check the bottom rad hose (again carfull this to should be hot) if the bottom one is cold then the chances are the thermostat is not working (this confuses me too as the thremostat is at the engine end of the top hose)

Hope this helps.

Hi, thanks for the reply.

I'll try this at the weekend. Do I need to be under the car to do this, I've had a quick look but can't see anything obvious. Maybe I need to take the engine cover off?

I've attached a picture of the two pipes I think your talking about, I've check both of them and they both appear to getting pretty hot.

I've driven the car to work and back yesterday and again this morning. Appears to be ok didn't overheat, although could see the dial slowly starting to creep up when I got caught in a bit of traffic. Still no hot air from the blowers. Coolant level is ok, oil level appears to be ok.

When I opened the oil cap there was a very small amount of smoke, the tiniest amount really. Is this normal? I'm not burning oil? I can't smell anything when driving.

Thanks.
 

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Sound to me like a heater matrix air lock, as there is no water movement through it, which gives a cold blower even when the heater is set to hot, also your water temp is ok whilst normal driving, but gets hot in town (no air forced through the rad) so it sounds like the circulation of coolant is being restricted.
The heater hoses are visable without removing engine cover, look from the top of the engine from the passenger side around where the gearbox joins the engine, between engine and windscreen, they have an air bleed screw no them looks like a gig black thumb screw turn it to open you should get water out straight away, I think in your case you wont, you need to get water flowing through the heater.
Once this has happens you need to ask yourself why this has dropped water, I doubt it will be a heater leak becasue you would have no presure there then which = no airlock.
If water does come out of the bleed screws you could be looking at a duf thermostat, they are designed these days not to jam shut so you will get water flow but very restricted which could be why you are ok on the move but getting hot when in traffic.
Just a thought, hope it helps.
 
the picture looks more like your bottom rad hose, try looking where Thrisey has said he's described the location better than I did.
 
Thanks for the advise guys, now appears as though the head gasket has gone. I've checked the pipes and both appear to be pretty hot. I've bleed them got a bit of air coming and then boiling hot water. Checked the oil cap and found a nice milky residue.

So it appears the themostat has gone, which has led to the head gasket cooking up.

Thing is the temperature gague didn't really go off the scale except for today it wasn't so bad that the engine cut out.

So if the head gasket has gone what sort of price am I looking at? Thing is the car is probably only worth £800 and needs a new cambelt in about 4000 miles.

Its a 2000 W so is too new for the scrappage scheme.
 
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