Observations on the 308 cooling system

Are you telling me there is a difference in the radiator between a Euro car and a North American car??

 

+1

I've done this modding some time ago and it works -I've put in a VW Golf switch bought at Busdepot-. That was my thinking; there's a little retardation between real engine temp/radiator temp readings, so when the real heat wave arrives to the radiator there's no effective time to cool down everything, and is worst if you are stuck on a traffic jam. So the needle starts to climb.

My 2 cents

 

But only changing the fan temp switch won't fix the issue. That was probably the first thing I ever changed on my 308 way back in 1997 and it didn't make a bit of difference in the past 15 years.

The only think that did was an oversized aluminum radiator. Mine has only been in for two weeks and temps are cooler outside but so far so good.

 

I've installed too an oversized rad but after that, changing the fan switch has improved my cooling system efficiency clearly -on traffic jam-. And I'm living in Spain with very hot summers...

And we have to discuss about the big deep radiator cores that we love to install on our cars... They are OK for track days and races, but not so good for everyday driving. We need radiator cores not so thick in order that the fans can do properly his job, blowing fresh air through them when idling, stuck in traffic. Too thick radiator cores do not help on that function. Thick core radiators works like a charm when we're moving, cooling even too much -in some cases, like on mine-.

 

This hits on it, make sure you have a good 1.1 BAR cap in place!

 

I may be getting a little too much of a good thing. I don't have many miles on it yet (less than 50) so it is WAAAY too soon to know anything, especially since it is cool outside right now.

But, on the highway the water temp gets pretty low. The first pick is around town before a highway run. The second is at speed a few minutes later on the interstate.
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I thought the thermostat would open and close with the temps enough to keep things "normal" but that's getting a little low to me, especially since it had been up to temp just moments before.

Or is that ok on the highway?

 

That's fine on the highway. Engines are dyno broken in regularly at 160-170 temps.

 

My 77 runs like the second pic. all of the time. rarely goes to 185 and rarely do my fans turn on. Oil temp follows the water temp.

 

That's good to know but, man....

It has NEVER run that cool on the highway in 15 years even in the winter. That big fatass radiator really works. I was going to install some Hayden fans but screw that now.

You did good, John. I should have done this years ago

 

My carby runs at 195 when cool, when its hot out or driving hard the temp goes to 225, that is where the fans kick on, and its drops back down inbetween 195 and 225 but sometimes will stay at 225 for a while.

 

I'm very pleased it came out well!

 

I would say perfectly normal -
since overhauling my cooling system and welding in a high perf net into my stock radiator,
my car has been running in the same temp range for the last 4 years or 15K miles (without ever overheating)

 

Welcome to the new temp zone with John's radiator. It takes time getting used to the new needle position but it's great. I would recommend the autobleeder to lower the in-town temps too but I know I will get tromped on.

 

That needle in the secont pic is actually to the left of the mark. It is difficult to make out but if you look closely you can see that it is. VERY different from what I am used to with this car and I have been staring at that gauge under every conceivable condition going on 16 years now. It will take some getting used to.

 

I also had a highway reading very low, too low it turns out, the thermostat was failing and the first sign is extremely low temps on the highway in this season. The low temp with the radiator is normal but too low isn't. The t-stat should keep the engine temp the same regardless of outside temps!

 

Same for me running on the highway, with the needle very below from 195, like in the second pic.

 

I have been watching this thread and a few others and have noticed a few things. But first let me say I have a new found respect for all my 308 brothers, I can see the passion that you all have for your cars some of you with some automotive back ground and some not as much, regardless of your back ground you guys work so hard on improving your 308’s and I applaud that. So I would like to offer my help if I can, first thing first the ideal temp is to maintain 195 degrees right……ok so what has changed from the 308 model to modern day cars? Also why is it that when driving down the express way it runs cooler then driving in traffic? The only answer I have is air flow……modern day cars use variable speed cooling fan……. Were the 308 only has a one speed fan. My idea is easy install a 2 speed fan and a 3 pole thermo switch. This like modern day cars will help maintain the ideal cooling temp of 195. What do you guys think ?

 

I don't necessarily agree that all 308's should run at 195*. The modern FI engines will run at 210* which seems to be the ideal engine temp which produces the least amount of pollutants. Also modern FI systems can adjust to give you the best A/F ratio. Now back to the 308. I am not familiar with the FI engines but I do know that my 77 carb car runs well at 160* which is the thermostat that is in the car. It keeps the engine at 160-170 in almost all driving conditions . I can count the number of times on maybe both hands that my temp gage has gone to 195* in the last 30K miles I have owned the car. Some will disagree but this works for me.

 

I can understand fans and fan speeds cooling the engine faster or slower once they are switched on but that has little to do with temperature control per se. Again the thermostat is the device that controls temperature. It then depends on the cooling system (fans and radiators) to provide a cooling function when called upon to do so. It shouldn't turn them on unless the temperature has risen too high and fluid is circulating in the radiator (hence the fan switch in the radiator). So if the engine temp is dropping to low it means that fluid is circulating thru the radiator when it shouldn't ( fans are off) because the thermostat is not working correctly allowing this. And now the temperature at the engine is too low. Therefore although the intent was good the suggestion of a multi-speed fan will have no effect at all on the problem of cold running engine in cooler weather. IMHO of course

 

Sorry guys maybe I should explain what i was referring too, the issues of 308’s running hot (not over heating) in traffic in high ambient temperature is what I was referring too, therefore the idea of a 2 speed cooling fan is to maintain normal operating in high ambient temperature in traffic.

 

Agree. A 2 speed might actually extend fan motor lifespan. Also may be the reason some cars (F40) the fans come on sequentially depending on temps.