Bypass Aux radiator 6 years on

[gmac78]

I would have expected the coolant temperature to be rising with the fan kicking in if this bypass was causing an issue. Certainly with the normal homefry my temp was always 2 or 3 notches under the 90 degC even when giving it some stick. The only time i would see the temp rising and the fan kick in would be idling or slow moving traffic. Perhaps if the bypass is plugged it will help keep the car cooler for longer when in slow moving traffic which to be fair makes sense. I will certainly plug the bypass to see if it makes any difference, i don't think it will but i'm intrigued now so must experiment.

[Nj]

The water will take the path of least resistance, so you can end up with higher flow through the bypass hose, and lower flow through the radiator.

Just pondering this. Does that also mean in the standard setup there's a possibility that a % of the water is going through the aux radiator and back to the return with minimal cooling, where it would be cooled more if it was forced through the main radiator? So if all the water was forced to go through both radiators that would provide maximum cooling, rather than having some go via either of 2 routes?

I'm about to do a timing belt and water pump change, and change my main radiator (again, since the last one was dead on arrival but I didn't know until I fitted it) so I'm wondering if my aux radiator is in mediocre shape if it's potentially acting like a bypass with minimal cooling?