Heating problem

Find someone with or just buy your own copy of VAG-Com. But 1st you could try a cheap thermometer & check the thermostat works.

Thermostat needs changing.

I have VAG COM and gave it a scan and nothing shows up.

It did have the cambelts and waterpump changed a few months before I bought it, I'm wondering if there is an airlock somewhere, but I did run the car with the coolant cap off and presumably ? the air would have bleed out ?

Hmmm...

Ahhh, on the say so of you and Duncan who seem to know engines like the back of your hands I'm going to buy a new thermostat thankfully just checked on and its only £8 + 40 for an O ring ... I thought it would have been a lot.

I'll post back results once it changed. I hope it works or a least cures the eratice temp needle moving.

Hypothetically if its not the thermostat what else would be in line to check ?

Thanks

A good way to get air out is to run the engine till hot then carefully release the pressure in the system, the air will bubble through noticeably if there is any still in there.

have a grope of the heater pipes when the car is hot, they should be so hot they hurt, check the radiator pipes for comparison. If all are equally hot but don't hurt then suspect thermostat, if the heater pipes have one red hot and the other just warm then suspect blocked heater, if everything is really hot then suspect heater flaps. You could also run it till the fan comes in and see if the heat from the heater is significantly better, again this would point at thermostat. Also time it takes for temp gauge to start moving is a good guide to thermostat operation. or start it from cold and keep feeling the radiator pipes, they should stay cold for a good few minutes before suddenly getting hot when the thermostat opens.

Hi MrC :) .. So you say I should run the engine till open and unscrew the coolant bottle cap a bit to let it any air escape ?

Are the heater pipes on the golf the ones which go ito the bulkhead in the middle at the back of the engine bay, there are two pipes so and go in the direction of the heater, so I'm guessing they lead to the heater matrix ? (I'll check those and report findings)

Ok, Ill have a good check of all of that and report back. Very interesting and helpful post :) thanks chap.

I've ordered the thermostat and o ring already as it seems to be pointing at that from what I understand, but a little extra investing won't hurt.

Thanks

First you have to check the waterpump is working correctly. Pull the hose off the header tank (when cold) and give the engine a rev and water should squirt out - if it just dribbles then its a waterpump.

Second these have an electronic thermostat - on the RHS of the motor there is a group of hoses and the one towards the front has the thermostat under it (30 torx bit) its plastic and if crook may come out in bits.

Hope this helps.

BTW its not usually the sensor.

Is this one of the engines with the plastic thermostat cover? If so I think the plastic wears and stops the thermostat closing properly and you need a new cap. It was in a thread on urcm but I don't know if it applies in this case.

Bit of an update as promised :) ... Ok I had the bonet up and on idle waited for it to get to 90, which is did in about 15/20 minutes, the top radiator hose got warm fastest and the bottom radiator one followed. The heater pipes both were hot. After it reached temp I turned it off and slowy released the coolant cap, and a wheeze of air seeped out and I tightened it back up. Also to add the heater pipes were hot but not scalding hot, I could happily hold it all the long, but I'm used to hot things being a chef, sometime I burn myself back when I started many years ago and hadn't even noticed! odd. Yep the heater pipes and the radiator pipes were about the same in hotness I'd say. It took a good 10 minutes before any heat was felt in the top radiator hose, the top warmed up faster the the otherside of it I noticed. But after 15 mins everything started going hot.

Also I forgot to mention I didn't have any air coming through the 2 middle vents on the centre console area, I found the pollen filter and found went leafs, and the filter it self was black, I dusted it gently with a soft brish to get the rubbish out and will pick up a new one. I cleaned out inside where it lives, I noticed the fitting to close the filter in was broken on the side so I guessmoisture, went got in, no dampness in the front passenger footwell. But I htink a new cover is in order. To add I turned the heater on and went to the front of where the pollent filter is and saw the heater motor ? spinning happily. Also went back into the car and no have heat in in the 2 front wents that no air was coming fron. It doesn't seem as powerful as the driver side vent or passenger side but better than nothing. Perhaps when the new pollen comes in it will be a bit better.

I've already ordered the thermostat so will change it and hope that cures all.

Advice or thoughts welcomed on my findings.

Hi rob, thanks for the info. I'll wait for it to cool down first then try and pray its not the waterpump. I'll pup the other in of the pipe into a bottle :) when my wife revs it if she'll help lol.

Ahhh, very handy to know when I change it.

very helpful :) (thumbs up) .. I just relied to Mrcheerful just now with my findings of what he originally suggested if you were interested :)

a little blow of hot air is normal, major glugging means there was some trapped. sounds like you are on the right track, it also sounds as though the thermostat is working, but whether it is at the right temp. sounds debateable. a combo of poor air flow and less than ideal water temp would give you a rather weak heater.

Thats why I suggested testing the water pump first with a simple test. One sharp rev is sufficient and you will not loose much coolant.

Then the T/Stat - which the plastic breaks.

Not normally the sensor which you replaced, these don't usually give problems.