High engine temperature

Question

I have used a Nissan Micra K12 1.0(CR10DE) that I've bought recently. It is running hot all the time no matter I'm driving it or not. I have checked the thermostat and found it removed, before that I took it for diagnostics scan due to hard starting and high fuel consumption and I was told to replace the crankshaft position sensor (replaced with no positive effect). What is the problem and how to fix it?

Answer 1

If I understand correctly, your thermostat was removed? In that case, have a new one installed.

Aside from that, there could be lots of reasons for your engine running hot:

• A blockage in the cooling system, e.g. if there's something blocking the radiator or one of the pipes have collapsed.
• not enough coolant.
• losing pressure in the cooling system, e.g. if there's a leaking pipe.
• a broken waterpump - this is my guess. The waterpump pumps coolant around the engine. If it's broken, there won't be any flow.
• the engine is running too lean (not getting enough fuel)
• the thermostat stays closed. Not your problem, but maybe for someone else.
• Not enough oil or the wrong type of oil.

Answer 2

One of the simpliest solutions is to check coolant route:

1. There can be air in hoses, add some coolant while revving engine (it will pump liquid and you can fill air with a liquid)

2. Check tubes for bend, it can stop liquid flow

Not sure crank sensor can cause heat, but o2 sensor can. If your AFR is lean it can produce more heat. Anyway, please provide exact coolant temp and environment temp, as if you are in Africa then even boiling water in radiator is ok ;)

Answer 3

The removal of the thermostat on an engine will cause poor circulation of the coolant and cause overheating on its own, especially at the furthest cylinders. On the Nissan K12 the timing chains have always have had a tendency to stretch. (They are a simple single link chain.) This may be contributing to a wrong diagnosis of the crankshaft sensor. Your cooling system needs to be professionally flow checked, to include a flow check on the radiator.

Answer 4

I believe the overheating may be due to absence of a thermostat which was removed. But how about the the high idling Can it also cause overheating of an engine?