Increasing coolant concentration to raise coolant temp?

[FCD]

So around 2016 i had the radiator on my '75 Capri completely rebuilt, it now has a 3 row aluminium core, ( originally 2 row ) which is great for the hot summers here in Spain, origially the cooling system capacity would be 9.4L, now i believe it's closer to 10 ( 2.46 vs 2.64 US Gal ), but now that it's getting cooler it takes forever to warm up until you get it on the highway and put your foot down, even then it rarely gets to the middle of the gauge, i tried a hotter thermostat, small improvement but not much, i went from a 180F to a 190F Thermostat, both tested in a pot of hot water before installing, the water pump is only a year old, and the fan clutch also is not very old and works as it should, i am running old school G11/G48 Blue coolant, the same Silicated stuff VW, BMW and MB used to recommend, so i am considering buying a 1.5L bottle of concentrate, draining 1.5L and adding the whole bottle of concentrate in there , the concentration right now must be somewhere around 45-50%, if i'm not mistaken this should reduce the cooling hability of the coolant a little bit and raise the mix to maybe 55/45 or something like that?, oh and the coolant temp sensor is new too and correct.
What do you all think of this idea?

 

[captainbeandip]

I probably don't know what I'm talking about here, but a higher concentration would reduce heat transfer ability. Yes, that means that your engine and water temperature would get hotter, but it also might mean that the amount of heat available to heating the interior of the vehicle might go down.

Besides that, the thicker mixture would be harder on your water pump.

These are both just guesses, so take them as you will.

 

[Jetronic]

cars take long to heat up, if the interior heating is on. Increasing the coolant concentration won't fix that. You will get hotter engine components though as you increased the nucleate boiling point.

Louvers to reduce airflow through the engine bay might be better, or making an undertray could have a similar effect. An electric fan also helps, vs a clutch driven fan.

 

[TomYoung]

I would suggest an inspection of your cooling system, and a drain and fill with in-specification coolant in the recommended concentration. I am pretty sure that if the cooling system worked at one time, heated up adequately, and does not now, that coolant concentration is a fix. I also would test the coolant that is in the system, since you don't know the capacity. You are working on a 50-year-old car, with a coolant system modified eight years ago. I would want to know if there is corrosion or a blockage in the system. I would also like to be sure that oil is not mixing with coolant, in even a small amount. I would like to know if the heater core is intact, plugged, corroded and if the water pump is in good order. Again, I think that you want the best modern version of coolant in the car (coolants have changed and improved) and think that changing concentration is going down the wrong road.

 

[FCD]

Well, the coolant spec from 1975 i think hardly matters anymore and is long outdated, after a long time researching i found G11/G48 to probably be the best, also recommended to me by people with other Capris like mine, i can assure you the cooling system is clean, i've changed the coolant every 2-3 years or so and it is spotless and as i said the water pump is only a year old, interior heating is not that much of an issue here except on the coldest days of winter which aren't that cold anyway.

3 Years ago i had to pull the whole dash out to change the blower motor for the heater core including the heater core and flushed it and nothing really came out, i can roughly estimate the coolant capacity to be about 9.7/9.8 litres as draining the whole system leaves little change from x2 5L jugs of 50/50, there is no indication of oil in the coolant or viceversa.

 

[bullwinkle]

The thermostatically controlled electric fan is a GREAT way to help with this issue, plus there would be some fractional gain in HP & MPG brcause of it. It's almost standard on newer (non truck) vehicles here-helps with the warm-up times too.

 

[FCD]

The thermostatically controlled electric fan is a GREAT way to help with this issue, plus there would be some fractional gain in HP & MPG brcause of it. It's almost standard on newer (non truck) vehicles here-helps with the warm-up times too.

I know, but i'm kind of a purist and want to preserve it as original as possible you know

 

[daniel327]

Stick an empty beer carton in front of half of the radiator during the cooler months. Don't forget to remove it before summer.

 

[zrxkawboy]

^^^quickest and easiest fix

 

[Snagglefoot]

I had a 76 Capri. Great car. I’ll just put this out there. Unlike most cars the thermostat for this car is on the front of the block but not under the top “ water neck” where the hose attaches. Weirdly, it’s possible to put the thermostat under the water neck by mistake. Would you like to provide a pic of where you installed your thermostat?

 

[FCD]

I had a 76 Capri. Great car. I’ll just put this out there. Unlike most cars the thermostat for this car is on the front of the block but not under the top “ water neck” where the hose attaches. Weirdly, it’s possible to put the thermostat under the water neck by mistake.

It is on the Cologne engine indeed, mine is a 3.0 British Essex V6 , the thermostat is on top as on most engines and the distributor is at the front, this engine was not offered in the US.

 

[whizbyu]

It is on the Cologne engine indeed, mine is a 3.0 British Essex V6 , the thermostat is on top as on most engines and the distributor is at the front, this engine was not offered in the US.

View attachment 252455

That engine compartment looks cleaner than my kitchen.

 

[Chris142]

Sounds like the new thermostat is bleeding coolant past it when it should be closed. Pretty common on aftermarket thermostats. Try blocking part of the radiator instead of goofing with the mixture.

 

[FCD]

Sounds like the new thermostat is bleeding coolant past it when it should be closed. Pretty common on aftermarket thermostats. Try blocking part of the radiator instead of goofing with the mixture.

I've tried several makes, including brand New old stock Motorcraft thermostats to no avail.
What i have done in the past is change the radiator for one i have from a 2.0 Pinto engine Capri, it fits directly in place of the original one and that does help it warm up faster as it holds at least a litre less than the original one, but it's kind of a pain in the butt to do that , i'll try adding more concentrate first and if that doesn't work i'll just block off a part of the rad and that's it.

 

[Snagglefoot]

Ok, on the US version, the thermostat is to the right of the water pump.

 

[oil pan 4]

So around 2016 i had the radiator on my '75 Capri completely rebuilt, it now has a 3 row aluminium core, ( originally 2 row ) which is great for the hot summers here in Spain, origially the cooling system capacity would be 9.4L, now i believe it's closer to 10 ( 2.46 vs 2.64 US Gal ), but now that it's getting cooler it takes forever to warm up until you get it on the highway and put your foot down, even then it rarely gets to the middle of the gauge, i tried a hotter thermostat, small improvement but not much, i went from a 180F to a 190F Thermostat, both tested in a pot of hot water before installing, the water pump is only a year old, and the fan clutch also is not very old and works as it should, i am running old school G11/G48 Blue coolant, the same Silicated stuff VW, BMW and MB used to recommend, so i am considering buying a 1.5L bottle of concentrate, draining 1.5L and adding the whole bottle of concentrate in there , the concentration right now must be somewhere around 45-50%, if i'm not mistaken this should reduce the cooling hability of the coolant a little bit and raise the mix to maybe 55/45 or something like that?, oh and the coolant temp sensor is new too and correct.
What do you all think of this idea?

Yep I've seen it several times. Cooling system is overheating, dip a coolant test strip in and it's maxed out 70+% drain off some coolant and replace with water. Now it tests 50 to 60% antifreeze and no more overheating.

 

[Snagglefoot]

You can use a laser pointed infra red temperature gun to get a real temp at the thermostat housing rather than rely on that 50 year old temp gage.

 

[FCD]

You can use a laser pointed infra red temperature gun to get a real temp at the thermostat house rather than rely on that 50 year old temp gage.

Hmmm, yeah, i have one, but god knows where, i'll have to dig it out and see, but it's a cheap one that i bought off Amazon so god knows how accurate it really is, but I'll give it a try i guess.

 

[AdmiralYoda]

The thermostat determines the minimum operating temperature and the fan, either mechanical or electric, determines the maximum operating temperature.

If your engine is running cool it doesn't mater what the fan or radiator is doing....ZERO coolant should be flowing to it as the thermostat keeps the coolant in the engine.

 

[FCD]

The thermostat determines the minimum operating temperature and the fan, either mechanical or electric, determines the maximum operating temperature.

If your engine is running cool it doesn't mater what the fan or radiator is doing....ZERO coolant should be flowing to it as the thermostat keeps the coolant in the engine.

The thermostat sure opens, but it takes a good while before the temp gauge gets to the middle or near to the middle, some people tell me not to worry, others say it's too cool, in the summer it's a different story ofcourse, it warms up rather quickly, and you can leave it idling all day on a hot day and it does not overheat.