Coolant flush to combat heater problems?
Discussion
Hi all,
Driving a 2015 Seat Leon. Recently I haven't got any decent heat coming out of the blowers. I had been hoping to do a specific heater core flush (as I'm hoping it's just gotten clogged up partially) but I have been having real difficulties trying to disconnect the coolant hoses at the firewall to do this. I had expected to find hose clips to undo but that doesn't seem to be the case on the Leon and it is some sort of more permanent plastic connection that I can't figure out or reach very well.
Anyway, I was wondering if just doing a clean out from the coolant reservoir and the radiator would do any good to the heater core? I'd do the process of draining and adding cleaner and water etc to run through the system then top up with coolant. Any advice would be appreciated. I'm confident I could just replace the heater core but I'm hoping it could be a simpler job.
Driving a 2015 Seat Leon. Recently I haven't got any decent heat coming out of the blowers. I had been hoping to do a specific heater core flush (as I'm hoping it's just gotten clogged up partially) but I have been having real difficulties trying to disconnect the coolant hoses at the firewall to do this. I had expected to find hose clips to undo but that doesn't seem to be the case on the Leon and it is some sort of more permanent plastic connection that I can't figure out or reach very well.
Anyway, I was wondering if just doing a clean out from the coolant reservoir and the radiator would do any good to the heater core? I'd do the process of draining and adding cleaner and water etc to run through the system then top up with coolant. Any advice would be appreciated. I'm confident I could just replace the heater core but I'm hoping it could be a simpler job.
Might be something useful in this thread: https://www.pistonheads.com/gassing/topic.asp?h=0&...
i'd suggest a bit of googling on this as it's surprisingly common and not always an air lock in the coolant system, there are various electrical gremlins which can cause problems with the HVAC system causing it to not open/close the flaps on the heater box which switch between hot/cold air. I have fixed a Leon in the past by disconnecting the battery, reconnecting it, starting the car and moving the temp range from Min to Max and changing between feet/dash/face vents. I guess the system figured out what it's dam job is!!
Has the coolant level dropped below minimum recently, on a Octavia I was working on I was having a bit of a nightmare bleeding the system. I assume the heater matrix is the same height as the expansion tank when the car is on level ground so ended up jacking the passenger side up to raise the expansion tank an continued filling it with coolant until over the max. I ran the car with a funnel still in the expansion bottle to allow the coolant level to rise/fall whilst the system got to operating temperature. With the heaters set to hottest let the engine warm up, once the fans have kicked in and run a cycle you cam switch engine off, leave coolant lid only semi tightened and allow to cool. Check the level again top up to max and screw the cap on fully.
Has the coolant level dropped below minimum recently, on a Octavia I was working on I was having a bit of a nightmare bleeding the system. I assume the heater matrix is the same height as the expansion tank when the car is on level ground so ended up jacking the passenger side up to raise the expansion tank an continued filling it with coolant until over the max. I ran the car with a funnel still in the expansion bottle to allow the coolant level to rise/fall whilst the system got to operating temperature. With the heaters set to hottest let the engine warm up, once the fans have kicked in and run a cycle you cam switch engine off, leave coolant lid only semi tightened and allow to cool. Check the level again top up to max and screw the cap on fully.
aka_kerrly said:
i'd suggest a bit of googling on this as it's surprisingly common and not always an air lock in the coolant system, there are various electrical gremlins which can cause problems with the HVAC system causing it to not open/close the flaps on the heater box which switch between hot/cold air. I have fixed a Leon in the past by disconnecting the battery, reconnecting it, starting the car and moving the temp range from Min to Max and changing between feet/dash/face vents. I guess the system figured out what it's dam job is!!
Has the coolant level dropped below minimum recently, on a Octavia I was working on I was having a bit of a nightmare bleeding the system. I assume the heater matrix is the same height as the expansion tank when the car is on level ground so ended up jacking the passenger side up to raise the expansion tank an continued filling it with coolant until over the max. I ran the car with a funnel still in the expansion bottle to allow the coolant level to rise/fall whilst the system got to operating temperature. With the heaters set to hottest let the engine warm up, once the fans have kicked in and run a cycle you cam switch engine off, leave coolant lid only semi tightened and allow to cool. Check the level again top up to max and screw the cap on fully.
Interesting fixes! I'll give the electical one a go certainly. My head is melted googling stuff already but I have certainly not seen anthring like this mentioned. Happy to fiddle around at it for a while before biting the bullet and buying a new heater core. Regarding my original question have you any opinion on cleaning the whole system with cleaner and water - would it do the heater core much good? Has the coolant level dropped below minimum recently, on a Octavia I was working on I was having a bit of a nightmare bleeding the system. I assume the heater matrix is the same height as the expansion tank when the car is on level ground so ended up jacking the passenger side up to raise the expansion tank an continued filling it with coolant until over the max. I ran the car with a funnel still in the expansion bottle to allow the coolant level to rise/fall whilst the system got to operating temperature. With the heaters set to hottest let the engine warm up, once the fans have kicked in and run a cycle you cam switch engine off, leave coolant lid only semi tightened and allow to cool. Check the level again top up to max and screw the cap on fully.
catman said:
did it happen suddenly, or just got worse gradually? Is your thermostat definitely ok?
Unfortunately I'm not sure how sudden/gradually it happened. My partner drives it these days as I'm commute free due to covid. She just told me about a month ago and I'm only getting round to looking at it now. I haven't checked the thermostat actually but I know it's not stuck closed as the engine hasn't been overheating. It's also just been through a full service - not sure what they would check but I did mention the problem and after they said its not something the garage deals with. Sheepshanks said:
Might be something useful in this thread: https://www.pistonheads.com/gassing/topic.asp?h=0&...
Thanks. Sent me down a bit of a rabbit hole of posts within posts. Gave me a few good ideas to try and also gave me a pit more insight on how to disconnect the hoses at the fire wall... Sort of. https://www.audi-sport.net/xf/threads/silica-bag-c...
Why didn't they just put long life coolant in? FL22 lasts longer than than most of the engines it was put into!
I've taken apart loads of 2005 - 2007 engines apart with the original stuff in and they're perfect inside.
Why didn't they just put long life coolant in? FL22 lasts longer than than most of the engines it was put into!
I've taken apart loads of 2005 - 2007 engines apart with the original stuff in and they're perfect inside.
Haven't got a chance to look at it yet but have been thinking about a possible thermostat issue. I took it for a drive last night after fiddling around to see if I could get any heat. It took about 10 minutes of semi high revving driving around for the engine to get up to temp. This seems to be a sign that the thermostat is stuck open. My question is though - once the engine gets up to temp wouldn't I get warm air in the cabin? After driving a while the blowers do seem to get a little warmer but if you put them on full blast they essentially go cold again.
catman said:
That says to me that the thermostat is screwed. As it's not able to regulate the temperature properly, when you take what little heat there is within the system by blasting it into the cabin, the water temperature drops rapidly.
Took it for a spin again there. The coolant got up to 90 degrees after about 10mins of driving. I blasted the 'heating' on the return journey and the coolant temp stayed at 90. I would have thought from you explanation I'd see the temperature drop no? stevee115 said:
Took it for a spin again there. The coolant got up to 90 degrees after about 10mins of driving. I blasted the 'heating' on the return journey and the coolant temp stayed at 90. I would have thought from you explanation I'd see the temperature drop no?
I don't think that represents the actual temperature - it's electronically fed from the ECU and it's basically just saying "OK". Don't know how much of a change it takes to move it.Sheepshanks said:
I don't think that represents the actual temperature - it's electronically fed from the ECU and it's basically just saying "OK". Don't know how much of a change it takes to move it.
Well the reason I took it out again is because I remember I can pull up coolant temp on the screen to give an actual value instead of just watching the gauge. I would have assumed that it's fairly accurate as it crept up from 50 to 90 degrees over the 10-minute drive. I could easily be wrong though! stevee115 said:
Well the reason I took it out again is because I remember I can pull up coolant temp on the screen to give an actual value instead of just watching the gauge. I would have assumed that it's fairly accurate as it crept up from 50 to 90 degrees over the 10-minute drive. I could easily be wrong though!
Might be different in wife's VW Tiguan, but the cluster temp in her car is the oil. It's blank for a couple of miles then comes on at 50.Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff