• Hi Guest why not show off your SEAT! (now fixed)
    You can now share your favourite car photos in the new media gallery including embedding pictures from your Instagram account.

Leon FR tdi 184 Coolant loss

tatters40

Active Member
Aug 3, 2018
11
0
Hi Guys

Can anyone help please

Read lots on this but never really found an outcome
In the last 3 weeks I've noticed my car has started using coolant.

On occasions it drops from max to min in 50 miles sometimes longer say 150 miles. Today i checked it after filling to the max mark 2 days ago and it was below the min mark.

There is evidence of coolant around the cap and sitting on the aluminium arm beside the expansion tank which i cleaned off previously and appears every time i loose coolant. Temp gauge never moves from 90.

Any thoughts, hoping not Head Gasket

Any new information regarding this issue please
 

bgb

Active Member
Jan 22, 2019
576
293
Search 'coolant' on here and you will find all findings others have had, or are finding.

https://forums.seatcupra.net/index....otorway-journeys-or-high-speeds.454370/page-8

The above is great for info currently - TDI and coolant loss is usually one of the following;

  • Heater Matrix
  • Coolant system foreign body blockage (rust, casting sand etc)
  • Water pump housing/Thermostat

there are non mechanical minded ways to possibly diagnose the above;

  • uniformed heat from all vents at high temp - if not could point towards coolant block/heater matrix block
  • spotting leaks - dependant on location, thermostat/pump - or just general crack in system
  • removing the filler cap and 'burping' the system - air lock

A good rated independent will hopefully be cheaper and more efficient at diagnosing than a dealer.

From experience though, its a very frustrating experience trying to pin point!
 

Brian Gordon-Stables

Active Member
Jan 16, 2020
223
75
Leicestershire, UK
Hi Guys

Can anyone help please

Read lots on this but never really found an outcome
In the last 3 weeks I've noticed my car has started using coolant.

On occasions it drops from max to min in 50 miles sometimes longer say 150 miles. Today i checked it after filling to the max mark 2 days ago and it was below the min mark.

There is evidence of coolant around the cap and sitting on the aluminium arm beside the expansion tank which i cleaned off previously and appears every time i loose coolant. Temp gauge never moves from 90.

Any thoughts, hoping not Head Gasket

Any new information regarding this issue please
Read that thread that bgb referred to. You'll see my most recent contribution. I also have a 184.

Not everyone has exactly the same issues but you can follow a process of elimination to try to suss it out.

If you have good coolant temp you can probably rule out water pump and t/stat for now. Having said that, the digital gauge will sit at 90 even if your coolant is anything between 75 and 98 because that's what mine did. An app that gives real time info is better. I use inCarDoc Pro.

A blocked heater matrix is probably the first place to start. Due to SEAT (VAG Group actually) designing a heater matrix with tiny channels in it, these get blocked over time. That is partly caused by casting sand being left in the engine block and/or silicant gel from a bag in your expansion tank that splits and gums up the coolant system. The way to test this is see how much heat comes out of your vents and whether you get a big difference from passenger to drivers side. A blocked matrix tends to cause reduced heat output and differing temps on each side. You can check the temps on the pipes in/out of the matrix as well.

If that is the problem, the coolant loss usually comes during a DPF regen. The DPF heats up to 600 degrees and does the regen. When completed it uses the heater matrix to help cool down. The car has 3 cooling systems (`circuits`) and with a blocked heater matrix it can't cool the coolant enough so it basically boils and it opens a release valve and shoots out of your expansion tank release port (just under the cap). With the car hot you don't tend to get a warning until the car has cooled overnight and the levels have dropped. Whether you do 50 or 150 miles might be less relevant as the DPF regen decides when you dump coolant.

A matrix is about £75. SEAT want about £1000 to do it (they quote 8 hours labour to remove the whole dash). Using a workaround guide on this forum, I did it in 2 hours.

May car was also overheating due to a faulty pump, so I've just had done:

New w/pump (inc cam belt)
New thermostat + housing
New coolant temp sender
New heater matrix
New expansion tank (without silicant bag)

If you get a DPF monitoring app, you can see if the coolant loss is linked to DPF regens.

I'm hoping that yours in just the matrix. It's a known issue although SEAT won't admit to it and I had to order my matrix from Europe due to high demand in the UK!

Quite happy to help with anything if needed but this forum has some good stuff on it.
 
  • Like
Reactions: bgb and MATT RILEY

tatters40

Active Member
Aug 3, 2018
11
0
Thanks Gents, appreciated, i hear various different Heater Matrix makes mentioned and updates to the original item, any recommendations
 

Brian Gordon-Stables

Active Member
Jan 16, 2020
223
75
Leicestershire, UK
Thanks Gents, appreciated, i hear various different Heater Matrix makes mentioned and updates to the original item, any recommendations
A lot of people opted for Nissens as they apparently have wider channels in them.

Some have said it depends if your car has Denso or Valeo matrix. Mine has a Valeo (2014 FR184 ST CUPA engine code). I chose to replace like for like. Apparently - the original Valeo has the original A version and a newer version in later models is a B.

Tried to check if the new one I got was the upgraded B version but couldn't tell. Either way, it's new and so much better than the blocked one.

This web-site is pretty good for getting the right part.

https://www.autodoc.co.uk/car-parts/oem/5q0819031b

I actually bought mine from these guys, but they might be the same people:

https://www.buycarparts.co.uk/valeo/7665313

From what I'd found on-line when I was looking, 5Q0 819 422 A for Valeo and 5Q0 819 422 for Denso or Nissens 73980. Having said that, the OEM number for the one I bought was (5Q0819031).

Happy shopping!
 
Last edited:

tatters40

Active Member
Aug 3, 2018
11
0
Thanks guys, i've tried everywhere i know in UK for one of these, even phoning Nissens in Coventry to check stockists, nothing available. Seat dealers are closing from tomorrow. Every review of the Autodoc site is worryingly bad (based in Berlin)
Brian, you had a good experience purchasing from these, how long was delivery mate?

many thanks
 

Brian Gordon-Stables

Active Member
Jan 16, 2020
223
75
Leicestershire, UK
Thanks guys, i've tried everywhere i know in UK for one of these, even phoning Nissens in Coventry to check stockists, nothing available. Seat dealers are closing from tomorrow. Every review of the Autodoc site is worryingly bad (based in Berlin)
Brian, you had a good experience purchasing from these, how long was delivery mate?

many thanks
Mine came from buycarparts, although I suspect that they are the same business as autodoc.

Bought on the 6th Feb, dispatched on the 7th and arrived on the 12th.

This was before the #lockdown, so really don't know current lead times.

Probably worth a punt as nothing in the UK is likely to change for a while?
 

ZK_FR150

Active Member
Apr 16, 2016
200
26
Mine came from buycarparts, although I suspect that they are the same business as autodoc.

Bought on the 6th Feb, dispatched on the 7th and arrived on the 12th.

This was before the #lockdown, so really don't know current lead times.

Probably worth a punt as nothing in the UK is likely to change for a while?
I believe they are the same guys as the website and format is the same.

In regards to Autodoc I've ordered a few times from them although it might take a week or 2 have no complaints with service and a lot cheaper than places here.

Again with covid-19 going on I'm not sure what the delivery time will be like but just contact them and see what they say.

Eurocarparts are showing in stock for mine 150 TDI for a Valeo one £220 can't think it wouldn't be the same part for 184 tdi, although that's quite expensive to how much they should be.

Hope you get it sorted
 

tatters40

Active Member
Aug 3, 2018
11
0
Hi Guys, bit more help if i may.

Found a Nissens Heat Exchanger on ebay, if i use the compatibility checker on their site it says it fits the Leon mk3 5F5 and 5F8 which i believe are the SC and ST versions, surely the heater matrix won't vary between the 3 door, 5 door hatch and estate?
 

tatters40

Active Member
Aug 3, 2018
11
0
Hi Guys

I'm going to drain the coolant and replace with some fresh G13. just dropped the undertray and can see any drain plug for the rad. looking a the front of the vehicle there are 2 pipes attached to the rad. 1 at the bottom and what looks to be a slightly larger diameter pipe 4 or so inches higher up. Can you confirm what pipe i should remove to drain, sounds like an obvious question but i understand there are numerous cooling circuits
 

tatters40

Active Member
Aug 3, 2018
11
0
Pulled the bottom hose (lowest) with the expansion tank lid open and very little coolant come out?
 

Brian Gordon-Stables

Active Member
Jan 16, 2020
223
75
Leicestershire, UK
Hi Guys

I'm going to drain the coolant and replace with some fresh G13. just dropped the undertray and can see any drain plug for the rad. looking a the front of the vehicle there are 2 pipes attached to the rad. 1 at the bottom and what looks to be a slightly larger diameter pipe 4 or so inches higher up. Can you confirm what pipe i should remove to drain, sounds like an obvious question but i understand there are numerous cooling circuits
Sorry - only just seen this.

When my guy did my car the other week he pulled off the bottom rad hose and got a fair amount out. Maybe about 3 liters. Some rads have a drain plaug but some it appears do not.

It is usually the fattest hose. How many you got to choose from?

There are 3 coolant circuits and not really sure how to get the max amount of coolant out but the rad circuit should be the main one.
 

tatters40

Active Member
Aug 3, 2018
11
0
Brian, thanks for the response again.
Replaced Matrix, simple enough job but now have a couple of issues
  • If i set duel zone to Hi, i got hot (very) air from the passenger side vents (LHS and middle), slightly cooler from the Centre drivers side and quite cool from the drivers RHS vent.
  • Still a few spots of coolant on the expansion tank after a drive. If i open the expansion tank cap (obviously slowly) after a drive it bubbles noticeably and hisses (appreciate this is possibly likely as it's sealed) until the pressure releases.
Very small amount of coolant spilled out of the rad lower hose, maybe a litre or so. There is a larger pipe on the same side approximately 4-5 inches above the one i released

Thanks as always
 

Brian Gordon-Stables

Active Member
Jan 16, 2020
223
75
Leicestershire, UK
Brian, thanks for the response again.
Replaced Matrix, simple enough job but now have a couple of issues
  • If i set duel zone to Hi, i got hot (very) air from the passenger side vents (LHS and middle), slightly cooler from the Centre drivers side and quite cool from the drivers RHS vent.
  • Still a few spots of coolant on the expansion tank after a drive. If i open the expansion tank cap (obviously slowly) after a drive it bubbles noticeably and hisses (appreciate this is possibly likely as it's sealed) until the pressure releases.
Very small amount of coolant spilled out of the rad lower hose, maybe a litre or so. There is a larger pipe on the same side approximately 4-5 inches above the one i released

Thanks as always
Interesting. Replacing the matrix should solve that. You sure you fitted a brand new one? It is possible it has an air lock in it or not fully bled. Not sure.

I replaced my expansion tank because I realised the lid wasn't tight anymore (it rattled when I took it off and shook it). New one is super snug (and no silica gel bag).

As for the rad - I'd take the larger pipe off and see what happens. I think the thinner pipe is for the charge cooler. The bigger pipe should be for the engine block. There are actually 2 rads so not sure if that will get any more coolant out. I was always taught, `fatter pipe, more fluid`.

 
Last edited:

Brian Gordon-Stables

Active Member
Jan 16, 2020
223
75
Leicestershire, UK
@tatters40 - forgot to say - if your matrix is good and coolant levels sorted etc, then there are other things that can influence the cabin heater.

Stuck actuators and/or faulty temp sensor in the vents. These are more subtle but a possibility.

I know you bought your matrix from eBay - just want to make sure you've not bought a used (blocked) one!

I have also just tweaked my post above in bold
 

tatters40

Active Member
Aug 3, 2018
11
0
Thanks Brian, New Nissens item purchased, old one defiantly showed some resistance when blown through. The vents that are hot are very hot much more so than previously. I left the side panel off and the flow and return pipes after a run are too hot too touch
 

Brian Gordon-Stables

Active Member
Jan 16, 2020
223
75
Leicestershire, UK
Thanks Brian, New Nissens item purchased, old one defiantly showed some resistance when blown through. The vents that are hot are very hot much more so than previously. I left the side panel off and the flow and return pipes after a run are too hot too touch
Ok. If the Nissens one is new then all good.

Ideally, with the heating on full blast (max temp) the return pipe should not be as hot as the flow (in) pipe, as the matrix heating is taking some of the heat out of it. Can you change the heaters settings to screen only and see what that does? Also try the lower (feet) setting. See if the temp is inconsistent across those. If it is, it might be a sticky actuator and it simply isn't turning the heat up enough. You can actually hear the motors whirring when you make the changes from feet/vent/screen.

Also turn the heat down to LOW and back up to HIGH. See if that does anything.

As for the temp sender - if you look through the grill on the dash vent nearest the door, you'll see a temp sender (thermistor) sticking up into the ducting. If this is faulty, it can send bad data and the heating systems lowers the temp to that side of the car. Apparently, these figures can be checked using VCDS to see if both LH and RH sensors agree.

The actuator motors can also apparently be checked using VCDS as well.

It's generally a process of elimination. If you're happy that the matrix is good and you have good hot water flow, then start looking at the above.

Everything that I have gleened has come from this and other forums, so it's not personal experience.

I'd probably want to make sure you've sorted taking off rad hoses etc and got your coolant levels sorted before you start fiddling with everything else.

Do you have access to VCDS?
 
Nimbus hosting - Based solely in the UK.