V6 Overheating - suspect water pump

[Simon Jones]

Good result . At least now you have replaced most of the system, so it should be good for years to come. Might we worth trying to measure how much water the old one holds for reference as it could be used as a test to check for blockages for other owners. Next time someone fits a new genuine rad, perhaps they could measure it too for comparison.

[ThisIsTheSea]

Thanks Simon! I will try and get some scientific findings from the old radiator.

I tested both the old and new thermostat this morning in boiling water. The new one opens faster and better than the original so definitely was worth doing anyway. As for the pump.... hmmmm... could have got away without doing that I think! Pretty much the only thing I didn't do was the hoses, but they are all in good condition so I will give them a while longer.

The cooling system runs so well now that it takes absolutely ages for the fan to come on and then after about 30 seconds it goes off! Job done!

[mikeonb4c]

Yay - problem solved!!

I took the old radiator out this morning. Poured water in through the filler and it all ran out through the top inlet - nothing from the bottom. It took the easiest route of escape.

At lunch time the new radiator turned up. Flushed it with cold water, put my hand over bottom outlet, filled with water and then removed my hand and it drained in approx 8 seconds. A vast difference from the 1 minute 15 seconds I got with the old rad. Amazing. Fitted it, bled, 40 minute test run and it's as cool as a cucumber.

I didn't fork out for the genuine Mazda radiator - I bought the cheapest Chinese one I could find on eBay. Works fine. I'm happy.

Thanks to all that contributed advice and suggestions. So, so relieved that I've finally solved it!

Excellent. The smart money was always on the rad I think. I've seen this before on Bongos at my mechanic Adrians place. Makes you wonder how many are running around undiagnosed, and how many diesel gasket/head failures may be linked to it, especially if a failing temp sensor isn't switching on the fans.