Loss of Coolant from Expansion Tank and i don't know why???
- Thread starter Angelo George
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- 184 coolant loss leak problem seat leon
Every 50 miles is really frequent!! Mine was never that frequent. I’d recommend you carry out a compression test on the block. Check your oil for any water. Do you get a loss in boost? Judging from how frequent your bottle empties I’m guessing it’s not the same problem
problem sorted had to go back to seat company and get cooling system flushed and then vacuumed all the air out of system
My Leon FR is having the exactly the same problem for about 3 months now, and it is happening more often and now on weekly basis. The coolant blowing out of the expansion tank and then drop to very low level, temperature on dashboard always fine and I replaced the cap as well. Got is checked in 3 different garages and they could not find any problems. So annoying...
Got it sorted for a short while, it’s not the head gasket as the car has covered over 5000 miles in the time the issue has been present and has not gotten any worse. If it was HGF it would have gone completely by now I’m sure.
Narrowed it down to a partially blocked heater matrix, due to the possibility of the silicone bag in the header tank splitting and sending silicone grit around the system, though I haven’t been able to confirm this yet as I can’t see the bag in the header tank to confirm it split. There are loads of posts online about the silicone bags if you research it.
I sorted the problem for a short while by taking the heater matrix out and flushing it which sorted it for a short while. I think I’m going to do a complete system flush, replace heater matrix and replace the header tank and go from there.
Th reason I think it has come back is the debris in the system had re blocked the small channels in the heater core slowing the flow to the EGR cooler and the lower flow rate causing the coolant to boil, introducing steam into the system and the steam pocket blowing the coolant out of the header tank as it travels to the highest point.
Probably going to give the system a flush this weekend and go from there. I’m not 100% it’s going to work but it’s worth a shot.
Cheers
Jamie
Narrowed it down to a partially blocked heater matrix, due to the possibility of the silicone bag in the header tank splitting and sending silicone grit around the system, though I haven’t been able to confirm this yet as I can’t see the bag in the header tank to confirm it split. There are loads of posts online about the silicone bags if you research it.
I sorted the problem for a short while by taking the heater matrix out and flushing it which sorted it for a short while. I think I’m going to do a complete system flush, replace heater matrix and replace the header tank and go from there.
Th reason I think it has come back is the debris in the system had re blocked the small channels in the heater core slowing the flow to the EGR cooler and the lower flow rate causing the coolant to boil, introducing steam into the system and the steam pocket blowing the coolant out of the header tank as it travels to the highest point.
Probably going to give the system a flush this weekend and go from there. I’m not 100% it’s going to work but it’s worth a shot.
Cheers
Jamie
I have the same problem.
I have had a new water pump, expansion tank and cap, system flushed out. Even took the heater matrix out and flushed it out and it was very clean with good flow of water. It's been pressure tested which was time too.
Each time I drive for more than about an hour the coolant comes out of the expansion tank overflow. Temperature on the car always says it's 90 degrees and no higher when it gets warmer up.
I did notice as well that when I put the heater on hot it will only blow warm air out of the passenger side and cool air out of the driver side vents!
It's frustrating as hell to find out what's wrong and if the heater and coolant loss are connected.
Any advice of what to check next or what the problem could be would be very much appreciated.
Paul
I have had a new water pump, expansion tank and cap, system flushed out. Even took the heater matrix out and flushed it out and it was very clean with good flow of water. It's been pressure tested which was time too.
Each time I drive for more than about an hour the coolant comes out of the expansion tank overflow. Temperature on the car always says it's 90 degrees and no higher when it gets warmer up.
I did notice as well that when I put the heater on hot it will only blow warm air out of the passenger side and cool air out of the driver side vents!
It's frustrating as hell to find out what's wrong and if the heater and coolant loss are connected.
Any advice of what to check next or what the problem could be would be very much appreciated.
Paul
any potential for air traps/locks? and what is the level like when its up to temperature and had a good run?
I would take the cap off (when cold), start the car up leaving cap off/loose, let it run up to operating temperature, leave it running for a period. then leave it to fully cool down (a few hours) before reviewing the level and replacing the cap. if the level dropped it would indicate you got some air out of the system.
I would take the cap off (when cold), start the car up leaving cap off/loose, let it run up to operating temperature, leave it running for a period. then leave it to fully cool down (a few hours) before reviewing the level and replacing the cap. if the level dropped it would indicate you got some air out of the system.
I have just went to my car to do as you suggested and was surprised that when I took off my expansion tank cap it was still really hot inside and it's been parked up for 3.5 hours. My journey to work is only 20 mins as well!
I don't have any of the tell tale signs such as milky oil, coolant leaking from the exhaust manifold, bubbles in my coolant, white smoke etc!!
Nor do I. What I have found is that if I only top it up to the minimum line, then it doesn't leak half as much. The coolant level rises to the max line though once the engine is warm. Probably needs topping up once a week after approx 300 miles or so. Got it booked in for a service on friday and also to have a look at the issue. Hopefully we find something :/
Mine didn't expand and overflow at all last week!
Last week my coolant didn't rise and overflow so that was a welcome change. Still haven't got any hot air through my driver side vents though.
Will hopefully have the sensors checked this week with a diagnostic check
Every 100miles i have to fill coolant tank, as i do 100miles on motorway, had put some coolant leak repair but that didnt sort out the problem too, i can see some coolant repair stuff come out coolant leak valve at the back too.
The car doesnt over heat or pass 90degrees, was he fans also work fine, no smoke and drives as it should do. It only has 60k mls on clock.
The car doesnt over heat or pass 90degrees, was he fans also work fine, no smoke and drives as it should do. It only has 60k mls on clock.
Hi all, I’m currently experiencing the exact same problem with my Leon FR, the expansion tank keeps emptying itself through the top after any long journey of an hour or so. Before it started leaking coolant it was also only blowing warm air through the passenger vents and cool through the drivers, I had it in for a service the other week and seat came back saying the silicone bag in the header tank was “ missing “ and they believe the little silica grit is now blocking the channels in the radiator and heater matrix, so I’ve got the car booked in tomorrow morning for a full coolant flush and a new expansion tank fitted, I’m hoping this will solve the issue. The coolant temp never goes above 90, the engine temp is always the same, but I have noticed the oil temp is higher now, it used to always run at 90 along with the coolant, now it’s always between 95-100, I’m not sure if this is connected or if seat are using a different type of oil now 
We all need to look at this forum !!
It look like the problem is getting solved !!
http://forums.tdiclub.com/showthread.php?t=483783
It look like the problem is getting solved !!
http://forums.tdiclub.com/showthread.php?t=483783
I have mine all sorted now. About 6 weeks ago I brought a new heater matrix for £80 the same make that was on the car. Flushed out all the system before installing. Total job took under 2 hours to do myself and haven’t had any problems since plus my heater works again. I think heater core blockage was causing pressure making coolant overflow from expansion tank overflow once it was hot.
I originally thought my old heater matrix was ok as both the in and out pipes were hot once warmed up so I assumed there wasn’t a problem with it and I also thought it must have been something else from stopping my vents from blowing out hot air. I just wish now that I had changed the heater matrix earlier.
But very happy now that I have no problems.
It really is a simple job to do as well with fairly easy access to the heater matrix. Most of the time was spent running the cleaner through the system and then draining it out.
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