My felicia is taking around 30 minutes to pump out even the smallest amount of hot air from the heaters (great in winter...). Does anyone know what the problem may be, and what the rough repair cost would be?

Broken thermostat (assuming 1.3 MPi), the part is aroung £45.

If your thermostat has the aluminum metal case instead of the plastic one then the repair will be cheaper, but it tends to be the "VW improved" plastic one's that fail.

Does the car have a slow warm up? If so, then it's the thermostat.

Otherwise, I'm wondering about a gunged up heater matrix, which probably means flushing the heater, engine and radiator.

Does the car have a slow warm up?

In what sense? (Sorry, I'm relatively new to car maintenance and I'm green about terms).

It's a post-VW Felicia, so it could be plastic casing. Is the part easy to fit?

Thanks for help so far!

Does the temp gauge on the dashboard take a while to rise from the bottom? I.e. does it take 5 minutes to rise or 30 minutes like the heater?

The thermostat is located at the top of the engine. As you look at the engine, it is to the right. It has a pipe leading to the top of the coolant tank, one to the top of the radiator and one at the back to the engine block.

If this is aluminium you simply need the thermostat, a gasket and an automotive jointing compound (I used hylomar gasket jointing compound which is blue stuff in a tube). Ideally start by draining the cooling system, you can just partially drain it if needed (you only need it so there is no water in the thermostat, but it is a good opportunity to fully drain the system, get the garden hose out, flush through the radiator and engine block - then renew the coolant, the best is g12+ ideally 50:50 diluted with de-ionised water and you'll need around 6 litres in total diluted I think [if draining fully keep the heater control on max heat to allow water to flow]). Best route to drain is removing the bottom hose from the radiator. Remove the three 10mm bolts and withdraw them, then inside remove the thermostat and remove the gasket. The hoses can be left in place but try not to kink/damage them. Give the old thermostat a visual check and compare with the new one, it may be stuck open. I had some difficulty figuring out the correct orientation of the thermostat to be installed, but my understanding is the jiggle pin is supposed to be at the uppermost point to bleed air, although the arrow is supposed to have some significance. Clean mating surfaces thoroughly, get the gasket and spread the compound on it very thinly (plastic glove helps), insert thermostat in correct orientation, put gasket over top, put housing back on, re-insert 3 10mm bolts. Top-up coolant (slowly if system was completely emptied) and run engine with coolant cap off to allow any trapped air in coolant system to escape, remembering to leave the temperature control inside the car on full heat, and turn off once the radiator fan has turned on then off.

No experience of the black plastic one but I assume it's much the same but you replace the whole thing and will need to remove the hoses. If it's the original clips they will probably be hard to remove and harder to put back on so replace with jubilee clips.

With a little care it is relatively easy, definitely a good thing to try if you're interested in getting in to a bit of DIY mechanics

I recommend topping up with just plain tap water for the first go after putting the thermostat in, you will be able to see if the heater works, and it will help flush the system through and avoids wasting coolant should you for any reason need to drain it again. Just do not run the car for long distances on water only, don't let it freeze and drain it after it's had time to cool then top up with the good stuff.

That's a great description of the replacement, thanks! I'll watch the temp gauge tomorrow to check the score, and I'll have a look to see whether the thermostat is the plastic one or not. Jorily Skoda has them for £19.99 at the moment so I'll grab one.

I've been looking for something to do on the car for a while as a first project (weather stops me dealing with rust for now), so this will be interesting. Hopefully I won't botch it...

Nice walkthrough anewman

Elegantly put Mr Newman. I agree fully, except that you may wish or need to use one of the Hermatite gasket compounds rather than Hylomar (both trade names). I can't remember which is which offhand, but Hermatite comes in Red and Green, and one is more suitable than the other for an aluminium to cast iron joint; read the instructions on the tube/box to find out which is which.

When replacing the plastic housing should a gasket compound be used with the rubber gasket supplied?

When replacing the plastic housing should a gasket compound be used with the rubber gasket supplied?

Definately not, fit that type dry.

Thought so, better to be safe than sorry and look more of an idiot later!

I'm still pending delivery of a new thermostat, but tonight - on an unusually hot night in Glasgow - my temp guage was hovering at just under 110 for 45 minutes.

Repercussions of this? Is it just the physical heat outside?

Also, the heater only blows out hot air not only when the temp gauge finally rises (on most cold days), but also only when the car is in motion.

Sound like thermostat?

Not a good idea to let the engine stay at that temp for long, as you could warp the head or blow the head gasket

God damn it; pay day's not for a week and I can't afford anything til then.

I've noticed a few people complaining about similar problems to mine; garage phoned to confirm the thermostat was knackered, for future reference.