2014 Leon Oil Temperature and Matrix

[Logan14FR]

Just looking some advice for the first time on here after lurking for a very long time!

2014 Leon FR 2.0 TDI 150,
The car dumped its coolant one evening after a drive of about 50 miles on motorway, just throwing up the stop car immediately coolant warning. Went out to find coolant all round the expansion tank. Had to leave the car overnight and return the next day to find more leaked out on the ground underneath! Topped her up and got her booked into the garage where no leaks were found. Since then she's ran fine, although rather hot. Coolant sitting at 90 (although we all know that isn't accurate) although oil temperature heats up and just sits at around 108-118 constantly- even in 10 degree ambient air temperature. But now the heater in the car no longer blows hot air (although this could have been like this for a while as i don't use the air-con much). Took off the panel into the matrix to feel it after a drive (13 miles or so) today. Both inlet and outlet pipes are cold with coolant temperature at 90 and oil displaying at 98. Does anyone have any idea what this could be? Thought it could be a heater matrix block although I'm really not sure, so i ordered one and will replace it myself anyway. Water pump and belt service etc all done at 87k miles with car now on 109k miles if that means anything.

Thanks for any help in advance.

 

[Woody_72]

Something's definitely wrong because as far as I understand it, the oil is cooled by the coolant in a heat exchanger type of device. I can only get my oil that hot by driving at triple digits on a quiet motorway (which I never do, honest guv!).

 

[Logan14FR]

Yeah something is definitely up, and I think it's more than just the heater matrix (in my unexperienced mind)! Just no idea what. Was looking through the workshop manuals to see if I could find a coolant-oil heat exchanger but couldn't! Hahah but of course, never see triple digits unless on the oil temperature gauge. Or maybe a quiet private road.

 

[martin j.]

Air lock at matrix?

 

[Logan14FR]

Air lock at matrix?

Was thinking this as she gurgles sometimes after a particularly warm drive if that would indicate anything. Would running her from cold with the expansion tank cap off help to release this? Thanks for the help.

 

[Woody_72]

If that doesn't sort it you might be better to find a local independent VAG place and have them hook it up to Vagcomm or VCDS to run the proper bleed procedure. I watched them bleed mine recently and it's rather interesting, the car sits there for several minutes revving itself up and down like a transformer .

 

[SuperV8]

Make sure you flush the cooling system before fitting the new heater matrix - there is something like 4 circuits within the cooling system so it's not as simple as just sticking a hose pipe in the radiator hose. Also the filling/bleeding procedure by the book you should use a diagnostic VCI to perform a bleed procedure - but I did mine without - just deep vacuum filling and has been fine.
I rarely see my oil temp above 100 - maybe 103 max I suspect when its trying to regen but I can't confirm this.
As mentioned there is a oil to coolant heat exchanger - so there shouldn't be too big a gap between your oil and coolant temps - as you mention coolant temp is a waste of time - unless overheating it won't budge from 90. Oil does seems to report actual oil temps.
For you heater matrix to be cold you probably have a air lock somewhere so no coolant can flow.

 

[BillyCool]

Just looking some advice for the first time on here after lurking for a very long time!

2014 Leon FR 2.0 TDI 150,
The car dumped its coolant one evening after a drive of about 50 miles on motorway, just throwing up the stop car immediately coolant warning. Went out to find coolant all round the expansion tank. Had to leave the car overnight and return the next day to find more leaked out on the ground underneath! Topped her up and got her booked into the garage where no leaks were found. Since then she's ran fine, although rather hot. Coolant sitting at 90 (although we all know that isn't accurate) although oil temperature heats up and just sits at around 108-118 constantly- even in 10 degree ambient air temperature. But now the heater in the car no longer blows hot air (although this could have been like this for a while as i don't use the air-con much). Took off the panel into the matrix to feel it after a drive (13 miles or so) today. Both inlet and outlet pipes are cold with coolant temperature at 90 and oil displaying at 98. Does anyone have any idea what this could be? Thought it could be a heater matrix block although I'm really not sure, so i ordered one and will replace it myself anyway. Water pump and belt service etc all done at 87k miles with car now on 109k miles if that means anything.

Thanks for any help in advance.

Just seen this. Did you get it sorted?

 

[Logan14FR]

Just seen this. Did you get it sorted?

I hope so. Matrix replaced along with a new expansion tank without the silica packet. Coolant system was all flushed through and we got quite a lot of debris out of it- some silica and some chemical sealant (which leads me to believe its happened before and someone thought it was just a leak). I've driven the car 20k miles a year for the past 3 years with no problem though! All very strange. Temperatures seem more stable now, but time will tell! Thanks all for your help.

 

[Leon FR 184]

Mine has just dump coolant out the expansion tank and now the passenger vents are blowing warm but not roasting and drivers side is stone cold. I’m taking that to be matrix and coolant tank replacement

 

[SuperV8]

Mine has just dump coolant out the expansion tank and now the passenger vents are blowing warm but not roasting and drivers side is stone cold. I’m taking that to be matrix and coolant tank replacement

I think most likely yes. Also best to do a coolant flush before changing the matrix.

 

[BillyCool]

Mine has just dump coolant out the expansion tank and now the passenger vents are blowing warm but not roasting and drivers side is stone cold. I’m taking that to be matrix and coolant tank replacement

More than likely. New matrix, header tank (without silicant bag) and as above, flush as much old coolant out as you can. If you drop the big/bottom rad hose, that should help. Changing the matrix itself only loses about 400ml.

 

[Leon FR 184]

I think most likely yes. Also best to do a coolant flush before changing the matrix.

More than likely. New matrix, header tank (without silicant bag) and as above, flush as much old coolant out as you can. If you drop the big/bottom rad hose, that should help. Changing the matrix itself only loses about 400ml.

So just drop out contaminated coolant fill system with water a couple of times and drain should be enough to remove the rubbish from the system.
Also how much coolant do I need to refill system after replacement and where is best to buy the parts from. I don’t want robbed by main dealer if aftermarket parts are of the same quality but can be purchased significantly cheaper

 

[BillyCool]

So just drop out contaminated coolant fill system with water a couple of times and drain should be enough to remove the rubbish from the system.
Also how much coolant do I need to refill system after replacement

The EA288 coolant system is a little `complex`. To do a proper flush you need special tools and VCDS to open/close various valves etc and back flush various pipes, all in the correct order.

My mechanic just dumped as much coolant as he could, flushed some distilled water through and then refilled with new coolant. Not quite what the tech manual says but it seems to have worked.

It's kind of up to you whether you want to go DIY or pay someone quite a few £££'s to do it the VAG way.

A drain, flush and refill should be okay. I plan to change coolant every 2-3 years as I no longer have the magic tea bag.

Not sure on the quantities. I'm sure Google can answer that.

 

[Woody_72]

I've just logged into my Haynes Autofix and total coolant volume is 8.0 litres.

 

[Leon FR 184]

The EA288 coolant system is a little `complex`. To do a proper flush you need special tools and VCDS to open/close various valves etc and back flush various pipes, all in the correct order.

My mechanic just dumped as much coolant as he could, flushed some distilled water through and then refilled with new coolant. Not quite what the tech manual says but it seems to have worked.

It's kind of up to you whether you want to go DIY or pay someone quite a few £££'s to do it the VAG way.

A drain, flush and refill should be okay. I plan to change coolant every 2-3 years as I no longer have the magic tea bag.

Not sure on the quantities. I'm sure Google can answer that.

Thanks, plan on doing it myself.

What is the magic bag in the coolant tank for anyway? Never seen it with any other manufacturers

 

[BillyCool]

Thanks, plan on doing it myself.

What is the magic bag in the coolant tank for anyway? Never seen it with any other manufacturers

The short version:

Due to more alumimium parts in the engine cooling system, the coolant can cause corrosion over time when it loses it's magical powers. VAG added the silicant bag to `top up` the coolant so it lasts the life of the car and shouldn't need changing (something else to appeal to fleet managers, like the LL 20,000 mile service intervals).

Silica Bag - Coolant MQB Engines

This may have been brought up before but after a quick search I couldn't find anything. I recently heard about these bags which are located inside the MQB engines (may be others) within the coolant tanks. They are small bags of silica which are designed to preserve the life of coolant but over...

www.audi-sport.net

The bag splits and sends little gloopy silicant balls into your already restrictive coolant system. The heater matrix really disagrees with them. Combine that with casting sand left over in the engine block as well, and it creates a few problems.

More recent VAG cars apparently don't have them as I think they have moved on to the next generation of coolant.

 

[SuperV8]

The short version:

Due to more alumimium parts in the engine cooling system, the coolant can cause corrosion over time when it loses it's magical powers. VAG added the silicant bag to `top up` the coolant so it lasts the life of the car and shouldn't need changing (something else to appeal to fleet managers, like the LL 20,000 mile service intervals).

Silica Bag - Coolant MQB Engines

This may have been brought up before but after a quick search I couldn't find anything. I recently heard about these bags which are located inside the MQB engines (may be others) within the coolant tanks. They are small bags of silica which are designed to preserve the life of coolant but over...

www.audi-sport.net

The bag splits and sends little gloopy silicant balls into your already restrictive coolant system. The heater matrix really disagrees with them. Combine that with casting sand left over in the engine block as well, and it creates a few problems.

More recent VAG cars apparently don't have them as I think they have moved on to the next generation of coolant.

Agreed & additionally there are different versions of silicate repository (mit Silikat marking on header tank) mine (2015 Leon 184) didn't have a 'tea bag type' - the repository was deep within the header tank on the coolant return input - so not removable. No idea if this later type also 'leaks' but I changed mine anyway just in case!

Latest vehicles don't have any silicate in the cooling system - as mentioned yes if was so the coolant would last longer - but it was always a moot points as VAG say whenever the cooling system is opened up for a coolant pump/timing belt change it says to flush and replace coolant and this must happen at 5 years.