Member Since: 22 Sep 2010
Location: Notts.
Posts: 8156
Heater not working after coolant change.
I have just changed the antifreeze and fitted a new coolant bottle and now the heater will not blow hot, I followed LR instructions several times and have tried everything I can think of and it still blows cold, I have even refitted the old coolant bottle but it’s still the same.
The D4 is fitted with a factory remote FBH that is designed to heat the cabin faster than the “standard” remote FBH, is there a procedure for bleeding the coolant in the FBH as I feel this may be the problem.
Advice most appreciated as I’ve been doing battle with it for a week and it’s near freezing in the cabin in these dark mornings.It can when others can't,
It will when others won't,
It goes where others don't.
9th Nov 2022 7:52 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13856
Hiya
Wonder if using something like this may help push any air bubbles out of the system
Hope u get it resolved as indeed must be frustrating particularly with the cold mornings not having the heater functioning, fingers crossed for u mate
9th Nov 2022 10:45 pm
Motolab
Member Since: 18 Oct 2019
Location: Sleen
Posts: 1820
Re: Heater not working after coolant change.
M3DPO wrote:
The D4 is fitted with a factory remote FBH that is designed to heat the cabin faster than the “standard” remote FBH, is there a procedure for bleeding the coolant in the FBH as I feel this may be the problem.
In that case normally a electronic operated valve is in the circuit….
The valve “short cuts “ the coolant circuit, so the heater matrix does get the warm coolant primarily
Only after the coolant has a certain temperature, the engine is warmed too..
What you can do: drive the car for a few miles….
Let it idle then (waterpump running) and apply 12 to that valve, since that valve is 12 v operated… it wil open and the water/air will be pushed through and vent eventually in the coolant bottle…
Click image to enlarge
This gives an idea what is involved when such a valve is in the circuit…
Although normally it will vent straight away if the engine is run a few miles and before the fbh is activated..Best regards
Harold
Always looking for Pre '55's & Pre war British Motorcycles! knowing or having one for sale? PM please. I visit the UK 6 times a year
Ps. I edit my texts quite often, english is not my native language, so I will edit My “typo’s” etc.
9th Nov 2022 11:40 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8156
I have now got the FBH working but not the car heater, still blows freezing cold, answer seems to be the vacuum pump but I can’t grasp how the pump works as is what powers it?- hand, compressor, electric, anyone got experience of them. I didn’t even know such a tool existed but there must be a demand for them looking at the different types on sale.It can when others can't,
It will when others won't,
It goes where others don't.
10th Nov 2022 6:11 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13856
Congrats mate getting one bit done
They run off an air compressor , also found a video , hopes it’s useful to u
10th Nov 2022 9:04 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8156
Thanks, looks like the answer to my dilemma It can when others can't,
It will when others won't,
It goes where others don't.
10th Nov 2022 10:44 pm
Mastertech
Member Since: 13 Apr 2014
Location: North East
Posts: 131
If you know any friendly VAG techs they should have a vacuum cooling system bleeder with an adaptor that fits. You will need to dump the coolant out and then vac and refill.
Only other advice I can give is try and get just the front end up in the air, when I worked at LR I would put just the front wheels on a four post ramp and lift it up. Gets the coolant bottle nice and high.
11th Nov 2022 7:05 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13856
M3DPO wrote:
Thanks, looks like the answer to my dilemma
Ur so very welcome , hope it resolves the issue for u
Have seen a good few videos where some vehicles need to have this done where it won’t bleed naturally
Plse let us know how u get on
12th Nov 2022 6:14 am
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8156
It can when others can't,
It will when others won't,
It goes where others don't.
12th Nov 2022 9:26 am
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8156
Well tried the vacuum pump but still no heater , the two pipes running down the driver side of the engine that feed and return the heater are virtually cold and do not have a any coolant in them, all that I can get out of them are a few air bubbles, this all started after I changed the coolant expansion bottle.
Iid tool shows the stepper valves (left and right) are operating.
The heater was working perfect before I changed the coolant bottle, best heater I’ve known in a car including the FBH.It can when others can't,
It will when others won't,
It goes where others don't.
22nd Nov 2022 4:35 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8156
Click image to enlarge
Click image to enlarge
Click image to enlarge
This was with the engine runningIt can when others can't,
It will when others won't,
It goes where others don't.
Last edited by M3DPO on 22nd Nov 2022 4:57 pm. Edited 1 time in total
22nd Nov 2022 4:53 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8156
Double post.It can when others can't,
It will when others won't,
It goes where others don't.
22nd Nov 2022 4:54 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10506
Well the options I can think of are :
1) Air lock.
2) Blocked matrix - Somehow you managed to get a load of rubbish into the matrix in the draining process.
3) some blockage lower down where the heater hoses connect at the front
4) Air lock at the top of the engine.
You could flush the matrix with a hose pipe to prove to yourself there is circulation there.
If that is ok, I guess you could disconnect whereever the heater hoses run to at the front of the engine bay to either flush or drain coolant to remove air (plug the engine side with thumb or cork so you don't drain the engine again. )
What happens if you remove the small hoses from the rad top to the tank. Does a load of air come out then ?
22nd Nov 2022 6:45 pm
Mastertech
Member Since: 13 Apr 2014
Location: North East
Posts: 131
Did you command the valves open before you vacuumed the system? You want all the valves open so the air is drawn out and then the coolant in. All the rubber coolant hoses should go flat/ pancake. Once the vacuum has pulled down as far as you can get it then fill the system with the supply of coolant higher than the expansion tank. Once that is done run the electric coolant pumps before starting the engine.
Do it on a cold engine not a hot one as the steam when doing the vacuum can cause it to not pull down far enough.
Failing this can you see the coolant circulating through the expansion tank at the bleeder valve/ screw?
22nd Nov 2022 8:30 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8156
The front wheels of the car are on ramps, the coolant drained from bottom hose, the heater was put on hot with fan running slowly. When draining had finished the bottom hose was put back on.
The engine was switched on and the heater control (climate) set to max hot with blower fan running slow, the main hoses were flat, I didn’t notice the smaller ones.
I don’t know what you mean by electric pumps? The engine had been running and was tepid, not hot. I can see the coolant circulating in the expansion bottle, I am using the car and temp on the gauge is normal.
When the vacuum was put in the test position at maximum vacuum with all valves switch off the vacuum was lost fairly quickly, I don’t understand this as there are no coolant leaks and the system holds pressure.
I didn’t get any instructions with the vacuum pump.
Thanks for your help.It can when others can't,
It will when others won't,
It goes where others don't.
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, the two pipes running down the driver side of the engine that feed and return the heater are virtually cold and do not have a any coolant in them, all that I can get out of them are a few air bubbles, this all started after I changed the coolant expansion bottle.
