1.8T overheating issues

[Nikz_tsc]

Hi guys

Been having a recurring overheating issue with my Cupra 1.8t lately. When driving normally or even hooning it, the gauge reads a constant '90' regardless of the conditions (which i understand due to it getting decent airflow), but after standing in traffic for a while, it starts to steadily climb up the heat gauge and eventually boils over.


- I have replaced the thermostat and water bottle
- Water pump has been changed to the steel type
- Radiator doesnt leak or has visible leaks
- Fan cycles properly, switching on and off regularly
-No coolant leaks as i checked thoroughly
-Flushed coolant and replaced with g12

Problem still persists though.


I did open the pipe couplers and found bits and pieces of what i think is the old plastic impeller that jammed up in one of the pipes



Its only then that i figured out the heater in the car never gets hot. Tried to dissapate heat from the motor by switching it on when the car overheated but the air just didnt warm up, assuming the heater core would be clogged?


The last thing i can replace is the actual radiator but this still leaves me pretty puzzled right now as to whats causing it.


I did flush the coolant system so the remenants of those impeller pieces should of been pumped out of the pipes by now i hope...


Need to scratch around a bit more to figure this out.


Any help would be highly appreciated. Thanks guys!

[Solo786]

Have you attempted pulling off the lines leading to and from the heater core and flushing with water and compressed air? once thats done fill up with new coolant etc and make sure there isnt an airlock any where else that also leads to heating.

In the rare instance it can also be symptomatic of a head gasket failure somewhere - but not adverse enough to mix water into the oil channel

[rajeev]

Hi. Are the fans cycling at the correct speeds?

[doctordubs]

Sounds like ur radiator is partially blocked. When ur moving the pump speed increases water flow. If the fans are coming on and off whilst stationary its definitely flow related ie blockage or it may also be a fault with the thermostat.

Sent from my GT-S5280 using Tapatalk

[THANAS]

Do both pipes in and out of the radiator get hot?

[Nikz_tsc]

So i did some digging around with the coolant system over the weekend and decided to flush the system a couple more times and a bit more of those plastic bits and pieces came out.


Fitted the pipes back, topped up coolant and cleaned the contacts on the fan switch as well. Tested both speeds and the fan works fine.


The fans cycle on high speed for approximately 20-25 seconds per minute intervals. Not sure if this is the correct timing for it?

The water pipes are both hot, so its safe to assume that water is flowing through?

Need to assess the heater core though. Tested in traffic for about 30 minutes and the car maintained optimum temperate.


Need to torture test it a bit more to be safe.

[Stompie]

highly doubt its your heater core thats causing issues. Reason saying is that when my water pump failed and about 6 months before that happened when the new cambelt and water pump was fitted my heater has never gone warm anymore and you need to bleed the air out of the core. thats the only reason why heater doesnt get warm cause its got air in it and no water gets to it to warm it up.

And my car has never overheated and needle has never moved above 90deg and i sit in ALOT of traffic daily.

[Nikz_tsc]

highly doubt its your heater core thats causing issues. Reason saying is that when my water pump failed and about 6 months before that happened when the new cambelt and water pump was fitted my heater has never gone warm anymore and you need to bleed the air out of the core. thats the only reason why heater doesnt get warm cause its got air in it and no water gets to it to warm it up.

And my car has never overheated and needle has never moved above 90deg and i sit in ALOT of traffic daily.

Thats what im finding odd aswell because my previous 9n3 never gave me this issue, even with the new owner its still fine. Hoping its not the water pump since its overheating after 30 odd minutes, and the water pump has been changed recently.

[Stompie]

highly doubt its your heater core thats causing issues. Reason saying is that when my water pump failed and about 6 months before that happened when the new cambelt and water pump was fitted my heater has never gone warm anymore and you need to bleed the air out of the core. thats the only reason why heater doesnt get warm cause its got air in it and no water gets to it to warm it up.

And my car has never overheated and needle has never moved above 90deg and i sit in ALOT of traffic daily.

Thats what im finding odd aswell because my previous 9n3 never gave me this issue, even with the new owner its still fine. Hoping its not the water pump since its overheating after 30 odd minutes, and the water pump has been changed recently.

I had a SKF metal impellar one fitted that only lastes a couple of months and next moment just water on the floor and it pushed the bearing sideways and the water drained there.

Almost snapped cambelt if it had to seize so was very lucky.

Changed with another make and since then no issues, just havent had time to "bleed" the air out of the heater core.

Hope its not head gasket...cause thats usually when you dont see leaks but overheat.

[Nikz_tsc]

highly doubt its your heater core thats causing issues. Reason saying is that when my water pump failed and about 6 months before that happened when the new cambelt and water pump was fitted my heater has never gone warm anymore and you need to bleed the air out of the core. thats the only reason why heater doesnt get warm cause its got air in it and no water gets to it to warm it up.

And my car has never overheated and needle has never moved above 90deg and i sit in ALOT of traffic daily.

Thats what im finding odd aswell because my previous 9n3 never gave me this issue, even with the new owner its still fine. Hoping its not the water pump since its overheating after 30 odd minutes, and the water pump has been changed recently.

I had a SKF metal impellar one fitted that only lastes a couple of months and next moment just water on the floor and it pushed the bearing sideways and the water drained there.

Almost snapped cambelt if it had to seize so was very lucky.

Changed with another make and since then no issues, just havent had time to "bleed" the air out of the heater core.

Hope its not head gasket...cause thats usually when you dont see leaks but overheat.

Dammit. Thats not what im keen on hearing now.