C5 BlueHDI 180 cooling issue

[Narardaru]

Hey guys!

I have found an issue with my car today and now I am really scared to drive it

When I bought the car the coolant tank was really gunked up so I immediately changed it. All was good. But I noticed that the level is dropping substantially. I have been topping up because I didn’t want to open the engine in fear of it being a head gasket or cracked block. Once after a long and spirited drive I decided to open up the bonnet and saw that antifreeze has been sprayed all over around my expansion tank. I thought that maybe thats where it all is going, so I bought a new cap but still the level was dropping.

Fast forward to today, I bought a testing kit for exhaust gases in the coolant system. The same one that I found out that my old E46 was burning coolant.

But while I was waiting 40 minutes for the engine to warm up the upper hose wasn’t even budging. Only slightly warm from the engine. The radiator was stone code. But at the same time the lower radiator hose was hot and also the expansion tank’s coolant was getting some temperature. The return pipe was starting to return to the expansion tank.

My guess is that the thermostat is completely stuck closed and only the coolant from the bottom hose somehow manages to go to the radiator from the block.

What do you guys think? When I was searching for a thermostat for my engine (if someone can confirm the part number) i found that it was only sold with the housing as one unit and it costed something around 500 euros, which I wouldn’t want to give only as a “maybe”.

I have noticed that my car stays around 95C at idle when doing errands and that pretty often the heat turns on from the vents when driving. Probably my guess is some backup mechanism to keep the coolant cool.

What are your guys’ opinions, I would love to hear them

Thank you!

[RichardW]

Blowing coolant without overheating is a good sign of head gasket troubles unfortunately.... Does the tank stay pressurised when the engine has cooled down / does it pressurise quickly when the engine is started from cold?

[Narardaru]

I really hope not

The tank stays pressurised even for a few days without driving. And it only has pressure when the coolant is starting to get hot.

I am just wondering or moreover looking for a confirmation that the thermostat is broken, since the lower hose is hot and the side from where lower hose is is where the overflow pipe that goes to the reservoir is. But the side of the thermostat (the upper hose) is stone cold and the radiator as well. Even when reaching operating temperature and starting the fans, the radiator is cold, but the lower hose is hot.

[Narardaru]

Also might I add I was doing a test for exhaust gases in the coolant and no bubbles or discolouration of the fluid occurred. But during the test I found this issue.

[RichardW]

If the tank stays pressurised for days, then almost certain the headgasket has gone. If the stat was shut closed, then it would overheat pretty quickly. I am pretty sure that on my 3008 1.6 HDi the radiator is up flow, i.e. the water enters hot at the bottom and comes out the top cold.