ho hum,,more hijet cooling problems


been reading the forum and most people seem to have similar problems that my 1300 hijet has,,,when driving on motorway speeds,the faster i travel (up to an indicated but highly unlikely 80 mph)the colder the temp gauge shows,infact it goes below the scale,but when stopped in traffic within a minute the temp rises sharply to about 3/4 when the fan kicks in,sometimes as soon as i move off again the temp drops like a stone,,but no matter where the temp gauge shows i have no warm air from the heater !! system has been bled twice,its not using any water or oil,rad caps have been checked and seem ok,,,only getting around 25 mpg at a steady 60 mph on motorways,,,someone please help as i love this little van and had big plans for it but at the moment its just not suitable for my use,,,could the EFi system be chucking to much fuel in as it thinks the engine is still cold and could my coolant woes just simply be a knackered thermostat ??? and can someone please tell me where the thermostat is before i start tearing it apart ?? !!!! many thanks


Fortunately, I've never had a problem with this in my Hi-Jet. The overheating problems were always on the old versions with the smaller engine sizes.

All you can do is use a process of elimination. Those erratic indicators that you describe make me think that either the water pump is faulty, your thermostat is stuck shut and needs replacing, or a sensor or two needs replacing. It sounds like the circulation of the coolant is a "stop-start" flow. Something is blocking the flow of circulation.

My experience of this is related to my Mazda Bongo. Going through the same hell as you. You need to check that no air is getting into the system via any hose leaks or the like as well. You've probably already done this.

good luck...

checked system,its airtight

checked system,its airtight with no leaks,,been messing with cars for 22 years and never had anything like this problem,,,think its gonna be a case of trial and elimination