Peugeot 4008 Overheating Slow Warmup

Greetings. The symptoms you describe, engine overheating coupled with prolonged warm-up times, do suggest a potential issue within the cooling system. Given the vehicle's mileage (141399 km), the thermostat should be considered a prime suspect. However, before jumping to conclusions, could you perhaps elaborate on whether the cooling fan is engaging at all? Furthermore, has the vehicle undergone any recent maintenance pertaining to the coolant system, such as a coolant flush or replacement of any components? Knowing this could give us a better insight.

Thanks for the quick reply! As far as I can tell, the cooling fan does seem to kick in eventually, but only when the engine's already running pretty hot. No recent work on the cooling system at all, it's been running fine until now. So, if it is the thermostat, is that a big job? And could it cause both the overheating and the slow warm-up?

Indeed. The behaviour you describe strengthens the suspicion of a defective map thermostat. A failing thermostat can indeed manifest in both overheating and prolonged warm-up times. In our experience, this is usually the case. The thermostat's role is to regulate coolant flow; when it malfunctions, it can restrict flow leading to overheating, or remain open causing the engine to take longer to reach operating temperature. While a competent DIYer might tackle this, given the potential for complications within the cooling system, I would strongly recommend consulting a qualified workshop for diagnosis and repair to avoid any unintended consequences. Be prepared for a bill of around 350€.

Thanks so much for the detailed advice! Sounds like it's beyond my limited skills. I'll book it in with a local garage and mention the thermostat. Hopefully, that's all it is. I appreciate you confirming my worries!