A theory question. I read about it elsewhere recently and I wondered if this has happened to me.

 

I have a polo 6N2, 8 valve, AKK engine. Overheated several times in August but trying to get to the root of problems since them. Likely head gasket blown or similar but not sure if I trust the RELD liquid.

 

My car is stuck on the drive while I diagnose.

 

So the question: Can running the car, up to operating temperature, with the thermostat removed cause it to OVERHEAT? If everything else was working properly including the fan. And assuming head gasket OK.

 

It would seem a straightforward no. But I read, elsewhere, that it's not necessarily that simple. Do you guys know different?

 

 

Edited 26 November, 20241 yr by cosaw

20 minutes ago, cosaw said:

But I read, elsewhere, that it's not necessarily that simple

Where, and on what vehicle/engine?

I would say it is a straightforward no, if everything else is OK.

Are you sure the water pump is pumping water?

Hi Pete,

 

Thanks for the reply. I read that the coolant can go through the radiator quickly and not have time to cool. That and other issues about flow in the block taking least path of resistance and accumulating in places where it can create hot spots.

 

One thread is here: https://www.forabodiesonly.com/mopar/threads/should-you-run-a-car-without-a-thermostat.153155/

 

So annoying, I can't find the most convincing thread now. That link is for a much older vehicle. Gonna look for the other link.

 

My vehicle is a 6N2 polo 1.4, 8valve, AKK engine.

 

There is no stat in it now (it was dead) as will be the end piece when I look I guess -he AA guy took the stat out to get me home. The first time I ran the vehicle up to temp without the stat it ejected coolant somewhere. I was also suspicious of the radiator fan switch.  (Which the MOT guy had to bypass to get it through the emissions test). The fan works when it is bypassed. I have fitted a new radiator fan switch and am about to put some new seals on the thermostat housing where the bung is and the temp sender (it has been weeping here). Old fan switch appears to work when tested outside the car though. Car starts and runs, and restarts even on old fuel. Reld tester shows emissions in the coolant system.

 

Water pump is well overdue for replacement. But it seems to be working. Heater core gets hot. Water goes through radiator to bottom hose.

 

So plan was to run vehicle up to temp with replaced fan switch/seals/expansion tank cap but leave the thermostat out. I haven't run it up to temp since August. That would be to test the fan switch. Then I rethought everything and wondered if I should put the stat in anyway.

 

 

 

Edited 26 November, 20241 yr by cosaw

I would completely ignore claims that it could run hotter without thermostat being fitted, especially if it's hard to track down such statements on the whole www.

Lots of false info is claimed as true, sometimes with great confidence. 

Hi Pete,

 

Thanks for the reply and clarification. Only just seen it. I'm kind of distracted at the moment. Got myself into a real mess with this car and my health. 

 

Just run the car and there is no heat coming from the heater core. I either filled it too fast or could filling it without the thermostat in cause the heater matrix not to fill?

 

Presumably the heater matrix is below the level of the expansion tank? I filled it without the engine running by the way.

 

Going to partially drain down from the bung on the thermostat housing and try to refill again and see what happens.

 

What I didn't understand is, the coolant capacity is supposed to be 5.6 Litres. I lost some when I drained from the bottom hose. Thing is I only managed to put 2.7 litres back in. Surely with the the thermostat out and the bottom hose off I should get most of the coolant out?

 

Think I'll have to start a new thread about getting the 1/8th of a tank of fuel out which has been in there since August. Read other threads but I have questions.

 

Edited 30 November, 20241 yr by cosaw