overheating

[fraz]

Hi guys

Im back again.
i did antifreeze on mistral on friday and afterwards everything was ok we went away for weekend but on our retrn on Saturday night the temperature shot up and the heater started blowing cold air.

i have felt both hoses going into the bulkead at what i presume is the heatr and both of them are hot suggesting to me that water is going through the heater but stills blows cold

also if i sit with it with the radiator cap offf the water heats up and throws itself out.

could this be caused by the thermostat or even the water pump.

how can i test both of these the water pump has no leaks

help
fraz

 

[Thermostat]

Fraz,

Firstly does the water level rise and fall when the engine is running at a constant speed ?
if so then you still have air in the system.
try this first not forgetting to top the level up when needed it usually takes about 45 mins to do.

you could try massaging the top hose while the engine is running, this normally forces the air out and water around the system.

also have the heater on hot and run the fan untill you get warm or hot air coming out and then check that the water level is roughly stationary.

Hope this helps

 

[fraz]

overheating still

Hi Guys

my mistral is still overheating if i leave it ticking over the gauge stays where it should be but if i drive it along the road a wee bit the needle shoots up.
i have replaced the thermostat but no matter what i do my heater is blowing cold.

Help required im going round in circles

could this be my water pump although it looks ok could the bit inside have stopped turning and how do i test this

cheers
fraz

 

[Terranosaurus]

When the needle "shoots up" does it throw all the water out too or does the level remain the same?

Is the radiator getting hot? Put your hand on it when the engine is up to temperature and see if it is how.

Is it using any water at all?

 

[fraz]

when i sit ticking over with radiator cap off the water level remains the same with guage at half way

when i put cap on and run along the road for 5 mins the needle goes to nearly red then drops back as bit

i can remove the cap when i get back but there is loads of steam and the radiator takes a lot to fill it

radiator still feels cold

heater is still blowing cold air

fraz

 

[Terranosaurus]

Have you ried running with no thermostat? Its not totally unheard of for brand new ones to fail.

I'm also wondering if it could be the head gasket. I had similar symptons on a (pre sprinter) Merc van years ago. The gasket had gone between the cylinder and a water way. At idle there was insufficient pressure to force combustion gases into the water ways but when driving the increased pressure was enough to force the water out of the rad past the pressure release cap - not sure what the heater was doing on that occasion.

 

[fraz]

just as i suspected all along i just wanted convincing

took of the waterpump and in the back of it there was no impellor thingy to drive the water around just a twisted lump of tin

will have to try and locate a new waterpump tomorrow

hopefu;lly will cure

dont understand how this happened though as the thermostat had jammed open at the same time


Straaaaaange
Fraz