Stepwgn Coolant Loss

The persistent check engine light coupled with coolant loss suggests a potential issue beyond simple air pockets. While head gasket failure is a possibility, presenting as exhaust gases entering the coolant system and pressurizing it, a less catastrophic cause might be at play. Begin with a thorough inspection of the radiator cap for proper sealing; a faulty cap can fail to maintain system pressure, leading to coolant expulsion via the overflow. Furthermore, scrutinize all coolant hoses, including those connected to the heater core, for evidence of seepage or weeping, even if minor. A pressure test of the cooling system, performed with a specialized hand pump, can identify small, otherwise undetectable leaks. Have you observed any white smoke emanating from the exhaust, particularly upon startup, or an unusual sweet smell, characteristics of coolant intrusion into the combustion chambers?

Thanks for the detailed response! I haven't seen any white smoke or smelled anything sweet, so hopefully that's a good sign. The radiator cap seems okay, but I'll definitely give it a closer look. Where exactly should I be checking for these weeping hoses you mentioned? Are there any specific areas that are more prone to leaking on the Stepwgn?

Given the absence of telltale signs indicative of head gasket compromise, proceed with a systematic examination of all coolant hoses and connections. Pay particular attention to the lower radiator hose, a common point of failure due to its proximity to road debris and engine heat. Furthermore, carefully inspect the hoses connecting to the thermostat housing, as well as those routing coolant to and from the heater core behind the dashboard; access may necessitate partial disassembly of interior trim. Although a visual inspection is crucial, bear in mind that minor leaks may evaporate before manifesting as visible drips. Given the complexity and potential consequences of cooling system malfunctions, consider a comprehensive diagnostic assessment by a qualified technician. They possess specialized equipment, such as combustion leak testers, to definitively rule out head gasket issues and pressure testing equipment. Early detection and rectification of underlying problems can preclude further escalation and more costly repairs. A cooling system pressure test performed by a professional can pinpoint even the most subtle leaks.

Thanks so much for the advice! I checked all the hoses I could easily get to and didn't find anything obvious, so I decided to take it to a workshop. Turns out it was just a leaky hose clamp that was causing a slow coolant leak. They replaced the clamp, topped up the coolant, and pressure tested the system. Cost me 52€ – much better than a head gasket job! Appreciate the help.