AX -overheated

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Jaf
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AX -overheated

Post by Jaf »

Sigh. 1.1 petrol, 1994. Red warning light came on. Got recovered home. Took thermostat out (it’s a bit slow but does open) and ran engine without it, got up to temperature but radiator fan didn’t cut in. Bypassed fan switch, fan works. Not sure if engine was hot enough for fan?

Leaks from the thermostat housing, suppose the thermostat forms part of the seal, so the system wasn’t air tight. I am hopeful Head Gasket is ok, I know they’re delicate! Will get thermostat, fan switch and thermostat-to-radiator hose tomorrow.

Question on the fan switch: there’s 3 ports for wires on the switch but only 2 wires. Stupidly didn’t notice! Any ideas! Or can I buy a 2 wire switch?

Thanks!
Jaf
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Re: AX -overheated

Post by Jaf »

Oh I missed out something. The alternator, which I replaced the brushes on only a couple of weeks ago, is shrieking like a banshee and the light is flashing. Am stupidly hoping it just got very hot and will shut up!
Jaf
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Re: AX -overheated

Post by Jaf »

Update.

New thermostat had no seal, grrr. Didn’t fit, double grrr. Chopped the middle out of the old one and put it back (will order another one).
Fan switch works (2 pin one).
Hose fitted on fine.
Ran her up to temp, just on the drive (I don’t have neighbours to annoy). All fine so *think* head gasket is ok.

Alternator. Well how strange. Was merrily complaining and flashing the warning light until it gave an almighty shriek and started working properly again.

Ha ha!
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xantia_v6
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Re: AX -overheated

Post by xantia_v6 »

Have you checked that the alternator belt is tensioned correctly?
Jaf
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Re: AX -overheated

Post by Jaf »

Yeah the tension’s good. It wasn’t a loose belt squeal, hard to describe, more like a metal rubbing noise. I took the belt off to check the bearing, it seemed ok. I’m *thinking* that the alternator bearing got very, very hot.
Burtdog6450
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Re: AX -overheated

Post by Burtdog6450 »

Hi I had exactly the same issue the other day and the warning light came on and then split the thin pipe about 10mm diameter which goes from the thermostat around top of the radiator and back down to the expansion bottle , can’t really investigate any further until I replace the split pipe anyone have a part number or diagram of the part I need thanks , I’m guessing just an air lock hopefully as it’s been stood a while the engine seems good since it’s cooled down

Oh mine is the AX gt twin solex carbs 1991 model

Regards Nathan
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white exec
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Re: AX -overheated

Post by white exec »

Hi, and welcome.

That pipe splitting will have removed the pressurisation of the cooling system, leaving it prone to boiling/overheating.
If you renew the hose, with luck that will be a fix.
Let us know how you get on.
Jaf
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Re: AX -overheated

Post by Jaf »

Hi Nathan. I got my hose from a spares shop, they had lots of shaped bits to compare.

I seem to have got away with the overheat! Hope you have too.

Got a weather warning of 47 for Monday !!!
Jaf
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Re: AX -overheated

Post by Jaf »

Question: anyone know if the passenger heater matrix contributes to the engine cooling with this car? I’m sure I remember putting the heater on in previous cars to help with engine cooling.

The passenger heater is absolutely rubbish so I’m assuming the heater matrix is bunged up.

Engine is still running hotter than I’d like, even without a thermostat (though this is my first summer driving this car and I’m used to cold-running Xantia). The engine radiator is teeny tiny and only has a one speed fan and putting the passenger heater on has no effect, presumably as the heater matrix doesn’t work.
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white exec
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Re: AX -overheated

Post by white exec »

Hi Jaf,

The heater matrix is always in circuit, and with the thermostat closed the circuit only consists of engine block/head, water pump and heater matrix. The matrix (if not blocked) will be at the same temperature as the engine. If heat from the matrix can escape (i.e. if heater flaps are open), it will contribute to engine cooling, but far less than the main radiator. When the thermostat opens, the rest of the circuit (i.e. radiator) comes into circuit.

You should be able to check whether the heater matrix is blocked by disconnecting the hoses to it (in the engine compartment), and running a garden hose through it to flush it out. You could also try blowing through it (a clean hose!) to judge whether there is any real resistance there.

Don't rely too much on the accuracy of the dash temperature gauge. Buy yourself an infra-red non-contact thermometer gun (cheap enough on Amazon), and use it on the cooling system and cylinder head to assess the actual temperature.
Jaf
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Re: AX -overheated

Post by Jaf »

Thanks Chris. I’m sure my dad had one of those temp guns...I’ll have to find it.