Golf GTD Mk7 Coolant issue light on dash (Temp needle remains in the middle) - Help needed!

[iworld]

Hi

I had my Heater Matrix and Coolant flushed out and replaced as I had a coolant light come on my dash and I kept topping it off before. The temperature needle previously always remained in the middle and I did drive it gently. When I got the work done, the mechanic replaced the matrix and coolant which he said took 8hrs to flush out the crap that was left in the pipes (How it takes 8hrs I don't know) The bag that VW put in the coolant tank split and made its way into the Heater matrix before I got the car. The mechanic also replaced the coolant tank with a new one. He said the Heater Matrix was blocked and he replaced it with one he had. Now after driving it back home, (gently) the coolant light came on again. He did advise me before I collected it that I would need to reflush the coolant again. I noticed a bit of oil in the coolant which was the same as before. The car has no loss of power and drives as normal except with this issue.

The dilemma................................... If i follow this mechanics advice with another flush, will the coolant light issue go away? The temperature needle always remains in the middle when driving even on motorway.

Another mechanic i know who said that he can bypass the oil pipe which is somehow allowing oil into the coolant. I want to know why the coolant is going down and where the coolant is going if i have to top it up every other day. Its worse in heavy traffic.

I just want as workable fix to this problem

i would greatly appreciate the advice

[Crasher]

Firstly, ignore whatever the temp gauge says UNLESS it reads anything other than 90, if it goes over it means the real temp is 117 and climbing so STOP! Flushing the cooling system of an MQB car has to be done more thoroughly than ever before as you must be confident there is no suspended silica fallout debris remaining in the system or you will be changing the matrix again, back flushing and blowing through with compressed air can take all day and at this time of year it is grotty, cold, miserable wet work. I have NEVER seen the silica additive bag split EVER, in fact if you try and split one it isn't easy, I would love to see proof. There is one engine type code I have come across in the pre 2017 Golf 7 GTD where getting the air out of the system is a complete sketch, the only way is to vacuum bleed the system at the same time as running the 900 second electronic bleeding process that I have only been able to get to work using the VAG system ODIS; it is listed on VCDS but we tried it last week and it did not work. I have had to do a few of these special bleed processes for other garages when they have done a water pump. An extremely important point on the MQB platform is to only use genuine (at the moment) G12 Evo coolant which can be bought ready mixed 50/50 or more suitably for our temperate climate mixed 40% G12E with 60% distilled water, tap water MUST NOT be used, this is critically important.

[iworld]

Hi Crasher

I was driving today and the engine management light came on. I have not got it plugged in yet but what would have bought that on? I was stuck on the motorway traffic but after driving when traffic cleared the light came on. I hope it is not anything serious. What do you think?

[Crasher]

Could be anything but the heater support pump could have failed.