Hi There,
we have a weird issue,
coolant loss out of the expansion tank cap,
suspected head gasket, but no bubbles in tank, compression test ok, hydrocarbon tast didn't show any,
replaced thermostat because temperature rise was really weird,
van now runs at a steady 77 degrees Centigrade,
eventually worked out how to bleed the system fully with pipe from heater bleed valve back to expansion tank,
if I leave this in place during tick over then the system just pumps water all around the system and no expansion takes place obviously because the cap is off, can drive the vehilce like this as long as we keep an eye on the temp gauge (installed an obd connected one) and the other eye on the coolant level.
if I replace the bleed cap and the pressure cap then expansion happens immediately, then there is air in the system again, and bleeding needs to take place again,
My question is around the egr system, is there a cooler and is it possible the egr cooler (not sure where this is) could be pressurising the system?
regards
Stuart