Car overheating with 25% coolant slightly?

[KrisZ]

The length of the trip should not matter. If the cooling system is operating properly, it is irrelevant if you do 100km or 1000km at once, the temperature should not climb.
Also, 50/50 mix is the proffered mixture rate, as the radiator pressure cap rating was chosen by the manufacturer with the 50/50 mix in mind. If you put more water than coolant, the boiling point will increase, unless a higher pressure cap is used.

 

[mightymousetech]

The coolant mix is not the issue. Pretty much every race car is run with pure water as coolant is not allowed, never an issue. You have a failure in the cooling system somewhere.

 

[BrocLuno]

My guess is the Thermostat is not functioning 100%. May be partially sticking so slow climb in temp. See if you can find an all SS marine grade T-Stat for that engine ...

 

[vintageant]

Not entirely on subject, but I have found that WaterWetter helps significantly in my old cars, except the Beetle, of course!

 

[mightymousetech]

Originally Posted By: BrocLuno
My guess is the Thermostat is not functioning 100%. May be partially sticking so slow climb in temp. See if you can find an all SS marine grade T-Stat for that engine ...

This would be my guess.

Pull out the thermostat and take a look, any scrape marks means it is sticking.

Look for shiny scrape markings on the wax capsule portion.

 

[FCD]

Will check the thermostat

all the ones i have are quite old so might aswell order a new one as they are cheap.

 

[Eddie]

I thought 50/50 was also for corrosion control as well as a coolant. Ed

 

[andyd]

use 50/50 coolant and if you're gonna replace the t'stat get one guaranteed to fail open. Did it use any oil?

 

[B320i]

Strangely, the recommendation in the OM for my BMW is a 60:40 mix, although I'm not entirely sure whether that's 60% water or 60% coolant. I've erred on the water side because its hot in Australia - not even a twitch on the temperature gauge.

What's stranger is BMW sells coolant in a 50:50 mix.

OP - check your thermostat for properly operation, and for a worn out water pump. I'd also be watching for any consumption issues in the coming weeks.
Last, but not least, is the engine fan on the Capri clutched or directly driven?

 

[FCD]

Originally Posted By: andyd
use 50/50 coolant and if you're gonna replace the t'stat get one guaranteed to fail open. Did it use any oil?

I checked the oil a couple times during the 1600 Km ( 1000 mile ) road trip and it did not change at all, i changed the valve stem seals a year ago, i will look at the t-stat soon, and maybe pu t in a different one as i have a bag full of them of 3 different opening temperatures.

 

[kschachn]

Originally Posted By: B320i
Strangely, the recommendation in the OM for my BMW is a 60:40 mix, although I'm not entirely sure whether that's 60% water or 60% coolant. I've erred on the water side because its hot in Australia - not even a twitch on the temperature gauge.

What's stranger is BMW sells coolant in a 50:50 mix.

It would be a 60% coolant mix per the BMW container instructions.

And pre-mixed BMW coolant? That must be an Australian thing as it isn't available here in the US. A search on Google doesn't show any availability of pre-mixed BMW branded coolant, are you sure about that?