Heater performance

[AliGTI]

Evening all. How does everyone rate the MK5 heater system? I've owned mine for nearly 3 years now and find the heater to be pretty mince. I've been doing some research of the Googling/Youtube type and think I might try back flushing the heater matrix. Has anyone given this a try before?

[ducman77]

Mine definitely improved big style when I swapped my thermostat?

Does your engine take ages to heat up? Or does the temperature drop when you're on the motorway? If so, your main stat is probably bad. Exceptionally common on these cars.

If your thermostat is ok I've heard the heater core flush is a good shout. I was gonna do mine but did the stat first and that cured the problem

[AliGTI]

Mine definitely improved big style when I swapped my thermostat?

Does your engine take ages to heat up? Or does the temperature drop when you're on the motorway? If so, your main stat is probably bad. Exceptionally common on these cars.

If your thermostat is ok I've heard the heater core flush is a good shout. I was gonna do mine but did the stat first and that cured the problem

Thanks for the reply. The car takes about 10mins to get the water temp up to 90°C which I think seems about right. At motorway speeds the temp stays bang on 90 even on ths coldest of days. Don't get me wrong it blows warm air but over a 40min drive if I have the heating on auto econ at 25°C it never seems to get to warm. My last car was a 1.0L Corsa and I couldn't stand the heat in that thing. Guess I have nothing to lose giving the matrix a flush...

[pudding]

Both the hot and cold outputs from the MK5 HAVC system is pretty lame tbh.  Probably a deliberate move after the MK2/Corrado heater matrices used to explode.

Anyway, 10 mins is too long to get to 90.   Mine was the same before I did the thermostat, and now it's about 5-6 mins to get to 90 when driven normally.  Obviously being sat in traffic from cold will extend the warm up time.

I remember my MK2 Golf days.  You could put the heating on full, hang a pig across the 2 window frames and spit roast the thing in an hour. 

[akbarirfan]

Both the hot and cold outputs from the MK5 HAVC system is pretty lame tbh.  Probably a deliberate move after the MK2/Corrado heater matrices used to explode.

Anyway, 10 mins is too long to get to 90.   Mine was the same before I did the thermostat, and now it's about 5-6 mins to get to 90 when driven normally.  Obviously being sat in traffic from cold will extend the warm up time.

I remember my MK2 Golf days.  You could put the heating on full, hang a pig across the 2 window frames and spit roast the thing in an hour.

Pudding which thermostat did you change?

[pudding]

Both the hot and cold outputs from the MK5 HAVC system is pretty lame tbh.  Probably a deliberate move after the MK2/Corrado heater matrices used to explode.

Anyway, 10 mins is too long to get to 90.   Mine was the same before I did the thermostat, and now it's about 5-6 mins to get to 90 when driven normally.  Obviously being sat in traffic from cold will extend the warm up time.

I remember my MK2 Golf days.  You could put the heating on full, hang a pig across the 2 window frames and spit roast the thing in an hour.

Pudding which thermostat did you change?

There's only one on mine (manual ED30) which is the main one under the alternator.

[Dan_FR]

The temperature can show 90 when the actual temp is as low as 75...... That 75 is only measured at one point in the cooling system and may not be throughout the entire coolant system.... It also takes time for heat to radiate and fully heat up the heater matrix etc.....

Think of your radiator at home..... hot water starts pumping through it very quickly, but it can be 10 minutes or more before the radiator is 'saturated' (is that the right word) with heat and starts radiating to do its job effectively.

I'll be honest and say mine is pretty naff if the car has been driven gently..... A few 'bwaaaarps' through a couple of gears to get some decent water flow and proper heat in to the system and within a few moments its lovely and toasty

[AliGTI]

Yeah I have noticed if you mash the right foot it warms up the cabin a little quicker.

Silly question here. The temp that shows in the dash is water temp. The engine/oil temp needs to be up to temperature before the thermostat opens, allowing the water to start cooling the engine and allowing heat to the heater matrix? Spot the noob!

[Dan_FR]

The stat is coolant based, not engine/oil temp based and prevents water from flowing through the coolant radiator

[mrw]

AliGTI - Since changing my thermostat last year my car tends to warm up in under 2.5 miles of mixed 30/40 morning traffic (unless its freezing!). I get ok heat once its 40/50c.

On the lead up to my stat problems I was playing around with heater temps - found dropping to 19 or 20 made a reasonable drop in times. I'm sure the stat was on its way out before the gauge needle started to drop when driving down hills etc.

[AliGTI]

AliGTI - Since changing my thermostat last year my car tends to warm up in under 2.5 miles of mixed 30/40 morning traffic (unless its freezing!). I get ok heat once its 40/50c.

On the lead up to my stat problems I was playing around with heater temps - found dropping to 19 or 20 made a reasonable drop in times. I'm sure the stat was on its way out before the gauge needle started to drop when driving down hills etc.

Thanks for your reply. Are you suggesting you have the heater temp set to 19 or 20 during warm up? My warm up time was with the heating all off. Sounds like I do have a stat problem.

[mrw]

Yes I was suggesting those temps on warm up! Not good with the heating off!

Are you manual or DSG? DSG's have an extra stat on the gearbox and I believe the early GTI's had a extra one somewhere else. If you're doing it yourself I used the guide from pelican parts which was really helpful, they also list the parts required. It was quite fun (!) and I think 2 hrs is with experience on a ramp, took me a lot longer but I was being extra careful. I had some issues with the bottom hose on the rad so had to use the alternative drain method.

Stat's normally fail open (safer, just means you're not heating a smaller loop) but I think my Dad had one failed closed!

[AliGTI]

Yes I was suggesting those temps on warm up! Not good with the heating off!

Are you manual or DSG? DSG's have an extra stat on the gearbox and I believe the early GTI's had a extra one somewhere else. If you're doing it yourself I used the guide from pelican parts which was really helpful, they also list the parts required. It was quite fun (!) and I think 2 hrs is with experience on a ramp, took me a lot longer but I was being extra careful. I had some issues with the bottom hose on the rad so had to use the alternative drain method.

Stat's normally fail open (safer, just means you're not heating a smaller loop) but I think my Dad had one failed closed!

Hmm I might visit my local garage and see how much they would change. I'm a bit strapped for time at ths moment. Cheers for the advice and help :-)