Strange cooling/heating problem got me stumped!

My 300 disco is acting strange.
Did a thermostat and water pump change, gen parts. New coolant, bled up ok.
Water pipe into matrix is hot, water pipe of of matrix is Luke warm. Heater blows warm , unless you race the engine and it will get hotter.

Why.....????? Hahaha

The viscus fan seems to over cool at idle, could that be it???? The gauge reads up to normal temp fairly quickly but I know that's not much to go by.

I have searched but can't find anything that matches my symptoms.

300tdi's always over cool, and the only reason you dont get as much heat at idle, is because the water pump is running fairly slowly, when you rev it, the flow will increase.

You are correct though, the engine is massively overcooled, thats why many people add electric fans, to get better efficiency without the weight of a fan on the belt! Hope ive helped!

Cheers chap, I've just bought a fan spanner. Might whip off the fan and see if it helps. I like the idea of keeping the fan. If it is the fan I will buy a new one.

Mudron said:

Cheers chap, I've just bought a fan spanner. Might whip off the fan and see if it helps. I like the idea of keeping the fan. If it is the fan I will buy a new one.

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Ran my 300 without a fan for 12 months, never got too hot even towing

sounds like a flow restriction as its warming up properly . now dont laugh my mgzr has had similar issues this month and i found a blockage in the return .

check the flow through the matrix with a hose pipe is a good idea ...

you could also check the flow from the engine with some see through pipe and no pressure short test . engine running

I think flow is the likely cause. Hot water leaves the cylinder head, to the matrix, then from the matrix to the lower rad to water pump pipe. The pipe out of the matrix is Luke warm to cool but the pipe into the matrix is hot. Might try flushing the matrix.