Thermostat or Water Pump? Telling Cooling Faults Apart on a Diesel Van
by Both cause overheating but the repair cost differs enormously. How to separate a thermostat fault from a failing water pump using hose temperatures, a bench test and live data.
Author: Bilal | Vans Guru
Writer & Editor at Vans Guru.
Bilal writes and edits Vans Guru. He researches and develops the technical guides published on this site, drawing on manufacturer and workshop technical literature, established repair references, and patterns reported by people who actually work on these vans. Vans Guru is a research-led information website, not a garage: Bilal doesn't carry out repairs or inspect readers' vehicles, and these guides aren't a substitute for a qualified technician diagnosing the van in front of them. Spotted something that needs correcting? Get in touch through the Contact Us page.
Head Gasket Symptoms on a Diesel Van (and What Mimics Them)
Head gasket failure gets diagnosed far too readily. What genuinely confirms it, which cheaper faults produce identical symptoms, and the tests worth doing before authorising major work.
Van Losing Coolant With No Visible Leak: How to Find It
Coolant is never consumed, so if the level keeps dropping it is going somewhere. A methodical guide to finding hot-side leaks, internal losses and cap faults on a diesel van.
EGR Valve Faults on a Diesel Van: Test, Clean or Replace
The EGR valve is blamed more often than it fails. How to tell a sticking valve from a wiring or sensor fault, when cleaning is worthwhile, and why the intake manifold matters too.
Diesel Injector Problems on Vans: Testing Before Replacing
Injectors are expensive and frequently replaced unnecessarily. Cylinder contribution testing, leak-off tests, why coding matters, and the high-pressure safety rules that are not optional.
Vauxhall Vivaro Overheating: How to Diagnose It Properly
A structured diagnostic approach to overheating on all three Vivaro generations, from reading the pattern of the fault to pressure testing, fan checks and knowing when to stop.
DPF Warning Light on Your Van: What It Means and What to Do
The DPF light is a request before it is a fault. What each warning stage means, how to clear it properly, why regeneration fails and when it stops being a driving problem.
Van Will Not Start: A Structured Diesel No-Start Diagnostic Sequence
Does it crank or not? That single question splits diesel no-start diagnosis into two very different paths. A structured sequence through both, plus the start-then-stall pattern.