Keep it cool & get warm
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  1. #1
    bob
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    Keep it cool & get warm

    Probably common knowledge amongst the clever people -

    The lousy heater on old Renaults needs a higher temperature thermostat to work properly - at least in my experience. But that will make it boil in the depths of summer - WRONG. It runs cooler.

    I guess that the higher temperature thermostat allows the radiator to cool down a bit longer and it therefore takes longer before the thermostat is fully open all the time.

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    It can take a while to find an alternative unit but I have found that it's worth the effort.

    Bob

  2. #2
    VIP Sponsor David Cavanagh's Avatar
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    Bob, What model old renaults are you talking about?
    David.
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  3. #3
    Simon's Avatar
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    I'm curious too, as one who has hammered a 12 across the Hay Plains in 35 degree heat, then had comments about how warm the heater is on cold nights, I reckon the 73/75 degree thermostat is spot on. If that is not old enough, the 73 degree 'stat on my R4's works well enough too. On limited runs so far, my 8 seems to be fine as well with a 75 degree 'stat. All are running coolant, and have clean systems. So it may be worthwhile having yours checked before the summer, Renault only recommend the 83/86 degree 'stats on the cold climate cars.
    1963 Renault R4 Van
    1964 Renault R4
    1967 Volkswagen 1300 Deluxe
    1969 Renault 8 Gordini 1300
    2002 Land Rover Defender Td5 130 - ex-CFA Region 4
    2005 Renaultsport Clio 182 Cup

  4. #4
    bob
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    David & Simon,

    The old fella was a 12 wagon (76?). Ran hot in summer and no heater in the winter. All flushed out and no change. I had similar problems with a 504, a flush out revealed all sorts of garbage in the system (a little air injected into the water soon shifts the muck). The 504 improved a little after cleaning but still got a bit hot in summer.

    Both cars improved out of sight with the higher temperature thermostat. I'm no mechanical expert this is just my results of "hands on".

    We had a 505 after that lot which was OK - heater was too hot if anything. I think it had some sort of thermostat on the water tap which took over your thoughts and actions.

    Our current transport, a 20, has a dog of a heater. I haven't got to this one yet but it will probably get the same treatment (save up for the next batch of anti-freeze first).

    Bob

  5. #5
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    Hi Bob,

    One of my cars is a '76 R12 wagon, and it has the best cooling system of any older car I've owned. In fact, I remember the first 40 degree day I encountered, when my stock BMW 320i got really hot, and the injection started playing up, the old Ren didn't even go above half on the gauge. Furthermore, the heater is fine - except for the crappy fan.

    I did read somewhere that the Aussie R12's had 'African spec.' cooling.

    One thing though - it slowly got worse and worse, so that during winter I had to get the radiator rodded out. Even though the rad. was 60% blocked (as the repairer advised), it was still only overheating in above 33 degree temps. Now it's back to its old self - the gauge runs constantly just above cold. And that's in traffic when the temps are above 30 like recently over here. A simple flush is not enough sometimes - the sludge has like a calcium buildup in it, and it won't budge. A rod job only costs $50.

    The rad man DID, however, mention that mine had a really good rad, which had close together corrugated fins and large pipes. When I asked if I needed a new core, he said to "hold onto this one as long as you can..."

    Maybe it's not the hotter thermo rating that did the job, but either one that's simply working properly (ie. opening wide) OR that's of a better design and allows fuller flow. In both cars

    Cheers

    Stuey


    2003 PEUGEOT 206 GTi

  6. #6
    Simon's Avatar
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    Stuey,

    Correct with the radiator, the AUS spec 12's are basically a poor road, tropical climate car, hence the bigger radiator and really good sump guard. The cold climate radiator ends where the fan shroud end on the left hand side, also thay have a shorter top hose.

    Simon
    1963 Renault R4 Van
    1964 Renault R4
    1967 Volkswagen 1300 Deluxe
    1969 Renault 8 Gordini 1300
    2002 Land Rover Defender Td5 130 - ex-CFA Region 4
    2005 Renaultsport Clio 182 Cup

  7. #7
    bob
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    Interesting, I've never had a radiator "survive" rodding. They allways "had to fit a new core" - obviously, there's a good bloke or two out there, you have to be lucky I guess.

    On the thermostat and hot weather, I think that the secret is not so much that it opens but that it closes, or doesn't open as much. A slower flow through the radiator must allow the water to cool a bit more. Once it opens fully, and stays open, the water will be flying through and the whole system will slowly heat up. The higher temp thermostat seems to offer greater control.

    The heater is pretty personal I suppose, some like it hotter or cooler than others - perhaps my heater cores have all been crook ?

    Keep chatting.

    Bob

  8. #8
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    Bob, I believe the theory is that a radiator will exchange heat faster where the temperature differential between the water and the outside air (ie. the temperature gradient) is greater, which is why they use colder thermostats in hotter countries.

    I've never fully figured out the theory, though. After the thermo is open, the rating would make no difference at all, because the radiator has a fixed capacity for heat exchange under given conditions. And they all open well below the boiling point of water, which in an engine is over 100 celcius.

    Cheers

    Stuey


    2003 PEUGEOT 206 GTi

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