Intermittent overheating

[simleybarter]

Greetings.
Having trouble with overheating. Needle to the top and red light flashing. Sometimes after only 3 miles.

Sometimes it sorts it self out after a few minutes and Guage goes down. Sometimes not.

When this happens the header tank can be bubbling and the main one cool.

I have new (reconditioned) 2.1 petrol engine.
New thermostat and both heat sensors.

From my limited understanding, Issue could be either radiator, water pump or thermostat ?.

Any advice appreciated.

All the best.

[Mocki]

The system is very simple....
The headertank ( the one in the engine bay ) should always be full to the brim, and the top up tank ( behind the number plate flap) should be full to the max mark when cold. When the engine is up to normal running temp the coolant expands and is pushed into the top up tank, when the engine cools down the coolant is sucked back into the header tank

So, first check is the darlek cap , then the header tank , make sure its not cracked , usually around the rim


The flashing red light in the temp gauge has two functions ....
1. If the gauge is above 3/4 and it's flashing it means over heating
2. If the gauge is below 3/4 and it's flashing , it means low coolant in the header tank.

[simleybarter]

Thanks.
Had already seen that when looking for answers on the forum.

Checked cap tightness. secure. No cracks.
And levels ok.

Still stumped.

[R0B]

The Dalek cap could be faulty. How did you test it?

[Mocki]

But is the cap working correctly , did you find the method for testing it ?
Your cooling system is designed to run at about 1 bar or pressure and this means your coolant no longer boils at 100° C but at a higher temperature of about 115°c.
You should get a “quack” when you blow through the cap , but cannot suck back

[simleybarter]

Thanks.
I had just done a visual inspection for cracks and that it was good and tight.
Will try the quack test in the next few days.

[jacobers]

If your engine temperature fluctuates and bubbles are forming in the header tank, it might be a radiator or water pump issue. Replacing them could help stabilize cooling. 

[Oldiebut goodie]

Suspect.
To keep an eye on.

[simleybarter]

Quick update
Expansion tank cap failled the quack test.
Replacement cap seems to have sorted the problem.
So far so good. For now....
Thanks for the help.

[Mocki]

You are welcome, thanks for bothering to come back and post the results

[simleybarter]

Unfortunately over heating issue not resolved

Story so far
Bought van in Germany.
Injector problems.
Bought reconditioned 2.1DJ
Fitted, but still problems with over heating.
Reconditioned air mass flow fitted. ( Mostly resolved an odd fluctuating reving)
New water pump and radiator fitted. All oil pressure switches changed. Thermostat & Expansion tank cap replaced.
The results are, still overheating. There is a crazy amount of pressure in the expansion tank. If driving for 30 min I will have to open the expansion tank cap to release pressure. The level looks low, but when I open the cap it fills back up again. This some times gets me back on the road for a while. But some times I have to do it quite often

Have I some cinder head leak ?.

Any ideas welcome.
My wife is running out of patience.
Thanks.