Technical Engine hot, hoses hot, radiator COLD

levets

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Sorted the issue with the thermostat housing, bled the system on an incline as per the guide on here. Just coolant coming out of the bleed valves... but radiator staying cold even though top & bottom hoses hot. Fan coming on as normal.... Also heater blowing cold only.

Is it likely that the radiator IS knackered? Is it worth trying to clean it out (flush) or would it be better to replace with a new one, bearing in mind I still have to take the radiator out and put it back... still might be knackered?

any other suggestions?
 

fingers99

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Classically, I'd say thermostat. But-----------

But it'd be worthwhile trying a proprietary flushing agent and then using a hosepipe to reverse flush the rad (bottom hose to the hosepipe). With a little dexterity and the odd plumbing fitting it should be possible to do it without pulling the rad (although that's not a huge job).
 
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levets

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Classically, I'd say thermostat. But-----------

But it'd be worthwhile trying a proprietary flushing agent and then using a hosepipe to reverse flush the rad (bottom hose to the hosepipe). With a little dexterity and the odd plumbing fitting it should be possible to do it without pulling the rad (although that's not a huge job).

Hi fingers99.....

put a brand new thermostat in last week... top hose gets hot... does that mean thermo is opening?

Easy to remove radiator? Even for a beginner? Haynes manual suggests '3 spanners'... experienced DIY mechanic.. I did the thermo replacement myself, is it any more difficult?

thanks in advance
 

fingers99

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It's easier than 3 spanners. Even with a jammed shut thermostat you'd expect the top hose to get hot eventually, but..........

This weather really doesn't help with diagnosis -- for oil changes I usually let the fan cycle twice. Last night it took 20 minutes on a stone cold Punto Mk1.
 

tinytim

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Even if radiator is blocked or thermostat stuck closed or both then the heater should still work; sounds as though there is still an airlock; have you tried bleeding the hose behind the throttle body with the engine hot and the heater lever set to max heat?
 
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levets

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Even if radiator is blocked or thermostat stuck closed or both then the heater should still work; sounds as though there is still an airlock; have you tried bleeding the hose behind the throttle body with the engine hot and the heater lever set to max heat?

Yep done all that... I'm baffled now.

This is what I did...
Put car on incline...
Removed both bleed valves (one on rad, one on heater hoses)
Removed cap off header tank...
filled to top and coolant came out of both valves... topped up and let coolant run out again....
whilst coolant running out, fastened valve on heater hoses....
topped up again and when coolant coming out of rad bleeder, closed it up...
ran engine til fan cut in and switched off....

Hoses hot, engine hot..... radiator stone cold....
 

Rhardman3

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Jan 23, 2008
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Im getting this same problem. i changed my termostat about 4 days ago as i was getting a red light coming on (the overheating light sorta looks like a dipstick) it comes on then goes back off again and no heat from heater. so i changed the thermo and for about 1 day the heater worked fine. Then yesterday and today nothing.

for example today i drove 12 miles from my sons and the overheating light came on i was getting no hot air from heater i could also smell burning smell and when i finally pulled up at my house the Rad fan was going ten to the dozen.

i bled the system when i changed the termo, im using the right antifreeze in rad and the correct split between water and antifreeze.

Im starting to think its a water pump issue any ideas on how to check
 

ralphnz

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If the water pump pulley is spinning (ie belt not broken) then doesn't this mean the water is being pumped? Isn't a direct drive sort of arrangement?
 

bredsticz

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You are supposed to tighten the bleed screws in the opposite order!
One on the top of the radiator then the one behind the throttle body, try that and see if it helps. Does sound like you both have an airlock though
 

DaveMcT

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Try putting the car on an incline nose up and crack the uppermost hose clip on the radiator top hose. Any trapped air should bubble out.

But first - pull off the intake heater hose from the thermostat as its a good way to release air. Only when coolant is flowing smoothly can you say its air-free.
 

DaveMcT

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Try putting the car on an incline nose up and crack the uppermost hose clip on the radiator top hose. Any trapped air should bubble out. (y)

But first - pull off the intake heater hose from the thermostat as its a good way to release air. Only when coolant is flowing smoothly can you say its air-free.

The bleed screw on the heater hose can also be taken right out to be sure its flowing coolant only.
 

ralphnz

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OK, so how do you know if the water pump is moving the water/ working OK>? How do fins 'wear away'? Aren't they made of metal?
 

DaveMcT

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Pump vanes get worn by cavitation. This is where vacuum bubbles form and collapse against the metal. It will also corrode if the engine was run on plain water for a time. Hard tap water is the worst of all as its alkaline.

Proper coolant reduces cavitation and stops corrosion.

Before you swap the pump make totally sure the coolant system is properly bled, the thermostat is working properly and the rad isn't blocked. When they are as OK as they can be the pump is the last place to look
 

ralphnz

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I have an uno that was run on water for a while.
Replaced the core plugs, they had rusted through. It's a FIRE engine, so same as punto. New thermostat, heater works. Temp guage goes to just below halfway (95 degrees) pretty quickly and stays there.

How can I tell if water is being pumped by the water pump properly?
 

DaveMcT

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If it warms up ok and the coolant temperature is stable in traffic and at speed, the pump and thermostat must be doing their jobs.
 
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