Oh yeah, why I don't trust my engine cooling system

[89ARIES]

Because even a 20 degree different in outside air temperature makes a noticeable difference on the scale. The gauge has always acted this way since I got the car. While idling, it climbs up to 2/3rds, maybe a little more, than takes its sweet time
coming back down to half. Yet, in cooler weather, even driving uphill, the gauge could be around 1/4th of the way up the scale or less. Yet, in warmer weather, in 93 degrees driving uphill up a freeway, not really that steep but some incline, it
started creeping ever so slowly up to 2/3rds even while cruising at 65-70 mph. So, I had the cooling system flushed this summer, but it didn't really make much of a difference. Now, even though I know the engine isn't quite overheating, my concern is that the fluctuations are putting stress on the headgasket. So, another member with this same phenomenon with his 89 Reliant 2.5 told me the cooling system sucks, and for me to get a 2nd engine fan and double corded radiator. I have driven other K-cars, including turbos, where the temperature gauge stayed nicely at 1/2 and was never a threat. Also, NO one has been able to tell me how the temperature gauge behaved or was suppossed to behave on the 89 Aries 2.5 when it was new from the factory. That would help.

[Pete in NH]

Guy,

Take a look at the core of the radiator, the area between the two side tanks. If the fins between the horizontal cooling tubes crumble like old, dried leaves when you touch them, that is very likely your problem. The original radiators used paper thin fin material, I’ve never seen such thin material. It’s not uncommon on old high mileage K’s to have the radiator fins go away. This gradually decreases the cooling ability of the radiator. My old 84 Aries developed this problem and I just replaced the radiator in my 86 Reliant over fin rot. Everything is back to normal now, gauge goes to half scale, fan comes on and it goes back to 1/3 scale.

Radiators are fairly inexpensive at rockauto.com about $65, The bad news is they are made in China like 95% of all new radiators these days