A10 overheating, stock thermostat and radiator cap values (Read 209 times)

[jonh]

Hi,

I'm having problems with my A10 engine (F10 F-II 100A) over heating at the moment. She's fine on a run (with air flowing through the radiator) but tends to overheat very quickly when stuck in traffic. She also seems to overheat faster the longer the journey - she can idle in traffic as soon as she's up to temperature initially fine but once I've been driving for a couple of hours if I get stuck in traffic she will overheat. I've just flushed the cooling system through (a bit gunky but not too bad) and replaced the water pump and belt. Now I'm turning my attention to the thermostat and radiator cap. Going from memory I think the thermostat fitted is an 87c one. Should I replace it with a 82c (is that the original value?). Also what should the pressure on the radiator cap be ?

Cheers,

Jon

[jonh]

Anyone ?

[gainsb1]

Hi. I'm not familiar with your model but does it have an electric fan? I had just the same issue on my 100a E10 and found it to be the temp. sensor. Fitted a new one with a manual switch over-ride (just in case) and hey presto! All sorted.
I'm a firm believer in starting with the cheap and simple and working up to the cheapest and not-so-simple.

There again, I also had the same issue with my 120Y and found that to be the rad; which looked okay after a flush out but a replacement from Will (Datman) sorted it.

Maybe this helps?

Leigh (Area rep)

[jonh]

Hi Leigh,

Yes it has an electric fan. I've replaced the temperature switch in the bottom pipe which controls the fan but it doesn't kick in until the temperature gauge is very high (I don't know when it should switch on). I don't know if the switch is working correctly or not but I got it from Will if memory serves. Unfortunately the housing which the switch screws into disintegrated and I had to epoxy it back together again so I don't want to risk changing the switch again any time soon. I had thought of fitting a manual switch to be on the safe side ! Or were you talking about the temperature sensor in the block, I haven't changed that one. Do you know what rating your radiator cap is ? I'm not sure if mine is the correct cap but it's got 13 on the top which I assume is 13psi which is 0.9bar. Is that too high ?

Thanks,

Jon

[gainsb1]

Yes. It was the temperature switch on the radiator pipe. You can take a lead from each terminal (2-core) and run the lead through to the dashboard where you can easily fit a toggle switch or similar. Just flick it on when needed. If you temporary fit this and then flick the switch and the fan doesn't kick in, this would suggest a dodgey switch/dodgey switch with epoxy resin. Although, seeing as you had a new switch from Will my thoughts would be to try the thermostat next (cheap) then if this doesn't work you might like to replace the radiator (not as cheap).

Good luck.

Leigh (Area rep)

[bananahamuck]

So does it physically boil over or are you saying the gauge reads it is overheating? If gauge, maybe try a different one,, or buy one of those cheap infra-red temp finders, to rule out that.

[jonh]

Leigh, the fan runs when I bypass the switch. I have had the fan running from the thermoswitch before but it only kicks in when the temperature gauge is at the first of the top two marks (very hot). With the fan running the engine runs a bit cooler but still not back in the centre when I'm doing over 50mph. I've replaced the thermostat (it was an 82c one already) but that hasn't made any difference. I had the radiator re-cored when I got her roughly six years ago, when the coolant was replaced the radiator looked pretty clean. I currently suspect that the heater matrix is blocked though - I hear a bubbling through it when I change gear (sudden change in rpm - causing a difference in the flow from the water pump).

'Bananahamuck', no it's not boiling over (I'm not loosing coolant) but the gauge sits in the middle until I do more than 50mph and then goes up almost to the highest mark (I'd say 80-90%).

The fuel economy has dropped perhaps 30-40% in the past few weeks too. Recently I've replaced the oil, the plugs and leads and rotor arm, fitted electronic ignition, the air filter is clean as is the fuel filter and I've also replaced the water pump, belt and thermostat. I've also had her tuned (she was running very lean before this - 0.1% CO). I'm wondering if the drop in fuel economy is a side-effect of the over heating or the over heating is a side effect of her not running efficiently. There are no nasty noises and the wheel rims don't feel hot after a run so I don't think the brakes are binding or anything like that, she isn't pinking and doesn't seem to have any less power than normal. I'm really at a loss to know what is the matter.

[gainsb1]

Well now.... It looks like it is simply a dodgey temp. gauge. Either replace it or forget about it. Classic car temp. gauges are notoriously inaccurate, unlike the modern ones. My Mum has an X-prefix Renault Clio and it doesn't even have a temp. gauge... just a light that comes on when a certain temp is exceeded. Further proof that seeing a needle climbing up tends to worry people.
You could try running it without a thermostat, although you might notice a drop in fuel economy as the engine will take longer to get up to the right temp.

Let us know.

Leigh (Area rep)

[jonh]

The temperature gauge sits quite happily in the centre up until about 50mph but above that she starts to overheat. I think the gauge itself is working correctly.

[dirtynails]

you should check the battery voltage while driving over 50 mph. could be an overcharging problem sending the temp gauge up.not unknown to happen with corroded wires on the voltage regulator. fuel gauge should rise as well though.

[jonh]

Interesting thought, any suggestions how I measure the battery voltage whilst driving ? The fuel gauge only drops as I drive ;-) !

[dirtynails]

Clip meter to any power point inside the car,radio,cigarette lighter,fuse box or even the interior light. Voltage isn't fussy!!! In addition though there is separate
voltage stabilizer in each gauge(i think-it's been a while-& my memory isn't getting any younger!) & they should run at around 7 volts so it still might be a clock problem.

[jonh]

Sorted it ! There was a partial blockage in the lower pipe running through the radiator switch housing. The engine is running at a normal temperature again :-)

Thanks for all your suggestions.