Overheating

[Elstro1988]

Yet another annoying problem's come to light.

The misfire has mostly gone thanks to saloonwoody's much-appreciated help (stuck and knackered points) and the points are going to be replaced...however, now this pain in the ass of a car is deciding to intermittently overheat...

Around town and speeds up to 40-50 mph, no problems whatsoever, drives and runs perfectly nicely, so driving to work isn't an issue.

However trying to stay at 60mph is a nightmare as it heats up rapidly and the speed drops. No problems with acceleration generally. Coolant is full. It used to squeak from the belt in the past but since the points got pulled apart the idle speed is fine but the the squeak has gone. Is it the belt or do I need a new water pump? There's no water leaking from the rad from what I've seen either.

I am going to take it for a proper service, but does anyone know what might be causing the overheating?

[mowgli]

jammed thermostat, possible but unlikely
gummed up radiator, very likely
head gasket possible
knackered water pump, possible

get the whole cooling system flushed out (remember to have the heating set on hot to clear it out too)
take all the hoses off & blast the system out with a hose pipe.

[Nova_Tek]

Odd one to be honest... start and run the engine with the coolant expansion cap off and let it get up to temp (safety first remove the cap slowly but don't remove if the coolant is hot/under pressure), check the return pipe to see how the flow of water is. It needs to be a consistent flow without any break/intermittent flow. If it's not constant than the water pump isn't up to the job hence bad cooling.

The stat generally jams open and more often than not would not allow the coolant/engine to get up to temp rather than the other way round but like Mowgli has said it is possible.

Flushing the rad first and clearing it will eliminate that, if it is still the same then it's probably the pump. While you are flushing you could even change the stat as they are cheap to buy.

[Elstro1988]

Right, an update.

Full service, points and condenser replaced.

Accelerates up to 60 and over fine in most roads, but up hills, it still really struggles to maintain speed, even for the 1.0 because it never used to be this bad. I was perhaps exaggerating when I said it was overheating...it went up to the middle line and slightly over. Never once hit the red. It just seemed harder work than normal to get up inclines.....according to Halfords Autocentre, nothing wrong with the cooling system.

Is it still worth flushing out the cooling system?

New filters, HT leads, etc put on, oil change.

[marc69]

Sounds unrelated but a distrubutor that doesn't advance will cause the car to overheat. I had this with a 1.0 ohv.

If the ignition timing is not advancing (again distributor) the car will have no power when under load and as the ohv is low on torque, hills will be the biggest challenge.