Forum:
A recently bought a 2nd hand diesel hi-jet, the van seemed to run ok but I thought I’d put it into a local garage for a service. The mechanic informed me that when he removed the radiator cap under the drivers seat water sprayed everywhere which meant that either the thermostat had gone or the head gasket. He said he’d removed the thermostat and to keep an eye on it, 2 miles from the garage the temp gauge shot up to max (where before it never went beyond normal) and it keeps doing this although sometimes it will drop if I put the fan heater on. Mechanic now doesn’t want to know. Any idea’s please? From a complete numbnut who can't understand why when everything was ok before this guy looked at it its now always showing overheating on the temp gauge.
Overheating.
Some engines do not like having the thermostat removed, the stat may act as a flow diverter to ensure proper water circulation to rear of the engine (this was so with a lot of early Leyland Heavey Diesels, 680's etc), if the stat is removed the coolant will take the shortest route possible to & from the rad thus the rear of the engine does'nt recieve proper cooling & so the engine over heats.
The fact that your vehicle did'nt overheat before the stat was removed suggests that the pressurisation maybe linked to another fault ( if indeed there was one). Would suggest you fit new stat & start again.
hijet overheating
I have recently put an 850 petrol in an ex diesel and am using the diesel rad. I too had terrible problems after the swap as the engine was getting very hot where it was ok with the diesel.For some reason hot water was reaching the bottom hose at the rad but the rad was staying cold(my rad has both inlet and outlet at the bottom!!!)anyway after lots of struggling I found that if I removed the top hose where it joins the metal pipe going to the rad and held this pipe high and filled it with water then blew down the pipe until water came out of the metal end(thermostat removed) it seemed to do the trick.Just one thing if you look above the radiator top(from the front of the vehicle) you should see a little rubber bung thing poking out from the body behind the rad. with a spring clip round it.I believe this is the bleed for the heater and needs bleeding too as this is a high point.I think the hijet runs hot anyway so I haven't bothered to replace the thermostat.As an added precaution I have bought an adjustable thermostat kit(£24) from www.nfauto.co.uk which allows me to set the fan to come on earlier. Hope this helps
A.Gilbert