Technical Overheating Multi

[multi_moo]

I am on a mission to resuscitate my near dead rather wheezy multi which I love dearly.

Put simply it is overheating!

The dash temperature gauge goes up to five/six. It has never exceeded three and I need to stop (frequently) and allow it to cool.

The interior heater blows tepid and the radiator fan appears not to come on at all, the radiator isn't getting hot so I suppose it has no need.

Would anyone have any idea as to what this might be I am a little clueless with this kind of thing. Many thanks in advance

 

[Most Easterly Pandas]

Sounds like a defective thermostat

 

[momoe]

If it is the thermostat, why would the interior heating be tepid?
I thought the heating was a loop directly off the cylinder head and not affected by the thermostat - I'd check levels, does the coolant look clean? Try bleeding in case of airlocks and if the coolant is clean, I would consider the pump.

 

[multi_moo]

Thanks I will try bleeding the system through and see what happens then try and find out whether it is the pump or thermostat. Is there any definitive way of telling which it is likely to be or is this more of a hunch thing?

 

[Most Easterly Pandas]

If it is the thermostat, why would the interior heating be tepid?
I thought the heating was a loop directly off the cylinder head and not affected by the thermostat - I'd check levels, does the coolant look clean? Try bleeding in case of airlocks and if the coolant is clean, I would consider the pump.

A good point I didn't pick up on actually. Could be the pump on its way out then

 

[momoe]

Pump or thermostat? It's overheating and there doesn't appear to be any circulation, the thermostat does stop circulation up to a given temperature but only to the radiator - you've got tepid air coming out of the vents even when it's overheating so coolant isn't circulating.
Check the coolant hoses and see if the hose after the thermostat is getting hot, then try squeezing the hoses to push a little coolant through, if the thermostat hose gets hotter then I'd say the thermostat is working and the pump isn't.
Pump has been known to lose it's impeller (plastic) and you can't tell until you take the damn thing off.

 

[pig]

Are you sure it's actually overheating, or are you going on what the temp display says?
Reason I ask is because my temp gauge started playing up- it would behave normally until it got to about 3 bars, then fluctuate up and down to six bars and then sometimes go off altogether.
Thinking it was the temp sender, I swapped it out, but its made no difference.
While it's fluctuating, if I turn on an electrical load (heated rear window for instance, or even the brake lights) the display goes up and down in sync.!
I'm guessing its an earth connection somewhere that is flakey, but until the weather warms up, I'll leave it.
The engine fan is on a separate temperature sender, so if the fan doesnt come on when the display says the engine has overheated, I'd suspect an electrical gremlin like mine.

 

[multi_moo]

Thanks for all your responses. Slightly naive question but where is the thermostat and is it easily identifiable? I have had a good look and while I can spot the water pump the thermostat is a little elusive.

 

[QinteQ]

- thanks to greyB
- have a look at this very site
- pictures and a walkthrough
- replacement stat & complete module here

 

[multi_moo]

Brilliant Thank you!

 

[QinteQ]

You're welcome my friend !