Overheating problem

[Skanderkeb]

Hi All,

I have a Golf Mk7 1.2 TSI from 2013, which
Started overheating. The gauge goes from 90 to 120-130 in just a few seconds and then goes back down as fast after staying there for a while. There's no pattern to it, it can happen after 3 hours of driving like after 4 minutes of standing still.
Electronic diagnostic did not detect anything.

I have changed the water pump and Belt, there are no coolant leaks, I purged the coolant circuit and filled new coolant. I changed the radiator and the fan works just fine.
I'm afraid this could be the head gasket but I don't want to go down that road until I eliminate all other possibilities.

Anyone had this problem before ? Could it be the thermostat ?
Thanks in advance for any help.

 

[MeltedSolid]

Sounds like maybe thermostat or hidden electrical issue, more likely the latter. Your water system won't change temperature by 30-40 C in a few seconds, so it's probably not a mechanical issue.

 

[jimlloyd40]

Do you have any white smoke coming out of your exhaust? If not it's not likely the head gasket. Probably the thermostat.

 

[Skanderkeb]

Sounds like maybe thermostat or hidden electrical issue, more likely the latter. Your water system won't change temperature by 30-40 C in a few seconds, so it's probably not a mechanical issue.

That's what I'm thinking too, but no electrical issue was detected upon diagnostic. So how to know what it is ?

 

[Skanderkeb]

Do you have any white smoke coming out of your exhaust? If not it's not likely the head gasket. Probably the thermostat.

No white smoke, no Mayo on the cap of oil tank, no oil mixed with the coolant, and no boiling coolant when the temperature is at 130⁰.

 

[Adurm]

Sounds like thermostat housing. My mk7 gti did it at 30k miles or so. VwoA took care of it. Within a few seconds of start up, it would overheat and go into limp mode. Sometimes i could shut it off and restart and be normal. Before i could get it fixed, the stat locked open and the car never heated up to normal temp. Fortunately it was stuck open and not closed and i could still drive it for a few days.

 

[jimlloyd40]

No white smoke, no Mayo on the cap of oil tank, no oil mixed with the coolant, and no boiling coolant when the temperature is at 130⁰.

That pretty much eliminates it being the head gasket. It sounds like it's the thermostat.

 

[Skanderkeb]

That pretty much eliminates it being the head gasket. It sounds like it's the thermostat.

New symptoms today, the car wasn't used for 2 days, coolant level was lower than what it was and when opening the Coolant Tank Cap there was still pressure inside. And when I turned the engine on, the car somehow vibrated a bit for a few moments after ignition.
It's driving me crazy, what else can it be, Before I change the Head Gasket ?

 

[Skanderkeb]

That pretty much eliminates it being the head gasket. It sounds like it's the thermostat.

I thought the thermostat comes within the water pump? which I have recently changed.
And would it create pressure in the coolant circuit?

 

[Skanderkeb]

Sounds like thermostat housing. My mk7 gti did it at 30k miles or so. VwoA took care of it. Within a few seconds of start up, it would overheat and go into limp mode. Sometimes i could shut it off and restart and be normal. Before i could get it fixed, the stat locked open and the car never heated up to normal temp. Fortunately it was stuck open and not closed and i could still drive it for a few days.

Did it also create pressure in the coolant system ? I opened the coolant tank, it released trapped air even after 2 days of not being run.

 

[jimlloyd40]

New symptoms today, the car wasn't used for 2 days, coolant level was lower than what it was and when opening the Coolant Tank Cap there was still pressure inside. And when I turned the engine on, the car somehow vibrated a bit for a few moments after ignition.
It's driving me crazy, what else can it be, Before I change the Head Gasket ?

I would not change the head gasket since you don't see smoke in the exhaust or have water in your oil. Still sounds like the thermostat but don't waste money throwing parts at it without a definitive answer. Is the temperature still fluctuating?

 

[Skanderkeb]

I would not change the head gasket since you don't see smoke in the exhaust or have water in your oil. Still sounds like the thermostat but don't waste money throwing parts at it without a definitive answer. Is the temperature still fluctuating?

Yes, still the same, flies up to 120-130 I stop, open the hood, engine is fine and fluid which should be boiling at that temperature is just fine.
How can I be certain that it's the thermostat ?

 

[jimlloyd40]

Yes, still the same, flies up to 120-130 I stop, open the hood, engine is fine and fluid which should be boiling at that temperature is just fine.
How can I be certain that it's the thermostat ?

Have someone verify your gauge is working correctly.