I have a Mazda 5 2009 Diesel CR19 143bhp with electric doors model. It has done 128,000 miles. I live in the UK.

Since last week, I noticed that the cabin heater would turn cold whilst driving even on the hot setting.
When I switch off the car, I hear the engine fan start up for about 10 seconds. Note - the engine temperature gauge on the dashboard is always in the middle.(never going to H)
When I open the bonnet, I noticed lots of coolant leaking around the expansion tank lid and dripping down.
I also noticed that the expansion tank was nearly full of coolant, nearly at the top just below the lid. (it is well beyond the "full" level indicator on the expansion tank).
When I open the radiator cap, it gives a pssss pressure sound - I have to fill about 1 litre of coolant.
I then drive about 15 miles, the cabin heater is hot and then slowly goes cold, etc etc - and the same above happens again and again.

Can somebody help me on how to resolve this issue?

Many thanks for your help.

 

Book it in with your mechanic. Could be something easy, could be a blown head gasket.

 

Thank you for your reply Grim_reaper. I took it to the mechanic. This is what he did, Hopefully it helps someone in the same position as me:

He kept the car on for about an hour (idle). Engine did not overheat - temperature gauge stayed in middle. Pipes were very hot. Radiator was still cold. Car heater was on. Then he asked me to put foot on accelerator pedal. Radiator went warm. Engine fan came on. He said he was happy - water pump working. He said it was probably a faulty radiator cap as I have never replaced it in 128000 miles.He replaced with a new radiator cap that I supplied for £6.99 from Eurocarparts. Refiled the missing coolant - 1.5litres, removing air bubbles patiently whilst topping up.

I have driven it for 30miles and did not notice any leaks when home. I will monitor all week and provide feedback here.
He said that if it still leaks, I will need to leave the car with him so he can perform a pressure test. He did not charge a penny even though I offered. Good honest guy. Hope this helps

 

Quick update. Coolant is still leaking from the expansion tank. It's not as much as before, but I have seen a few drops trickling down from the expansion tank.
Also, I notice a build up of coolant in the expansion tank well above the full line.
Any ideas from you experts before arranging another booking? thanks

 

As previously mentioned, these engines are well known for faulty head gaskets

Get a combustion gas leakage test done on the coolant..

 

Quick update. The garage tested and confirmed that combustion gases are getting in the coolant, and now causing soapy bubbles in the expansion tank. They confirmed that the Cylinder Head is faulty. They said that the cost will be £1600 and no guarantee that the head does not crack on removal. The car has a value of only £500 (costed £24K 11 years ago!), so this is completely cost prohibitive and no guarantee.
Very upset with Mazda as you would expect better build quality than this. I really looked after this car and was expecting alot more out of the engine yet!
I have the electric doors, tv, rear dvd's in both head rests, front/ rear sensors, rear camera, full leather, usb's, front dvd, terrestrial tv, satnav, blutooth etc etc.
I dont know what I'm going to do?
The mechanic said to try steel seal first. In his experience it has worked sometimes but no guarantees!
Any recommendations on what my options are as I really dont want to scrap this car as the body is very good as well and still drives smoothly despite this issue? Thanks

 

It's confirmed that combustion gases are getting into the coolant from the head gasket. What options do I have? Thanks

 

Price up a second hand engine.

 

Quick update. I tried Steel Seal as recommended by the garage but that did not resolve the problem after draining and putting in new prestone coolant.
I then located a 2nd hand engine off ebay for £650, 56000miles. All good. Fitting was £450 at the garage. Total was £1100
But before I bought it, I wanted to do a second opinion as to whether there were definitely combustion gases in the coolant - wanted to see for myself. Every garage was too busy, so I ended up buying my own kit, and tested it, and to my horror, the blue liquid did not change yellow, even after 5 minutes. I couldn't believe it. This meant that my Cylinder Head Gasket was OK.
I then read up on the net that white frothy bubbles in the coolant could also be caused by a dodgy thermostat that sporadically opens and closes causing a churning and bubbling effect.
Bought one for £7 from Eurocarparts. Paid a different Garage £40 to fit it. Replaced the coolant again. It's been 2 days and so far so good. The white frothy bubbles have gone and the coolant level has stayed the same. Thermostat was the issue. How bad. Got my car back!
I just wanted to share to everybody ... big lesson learnt. PHEW!