Is anyone running an aftermarket radiator on their is250? Looking to replace mine with aluminum with little to no modification required to install. What rad are you running and what has been your experience with it so far? Thanks!

 

...have you looked at your stock radiator? Should already be entirely aluminum, as far as the coolant sees. While the radiator is relatively thin, the GR and UR engine blocks don't hold very much coolant, so the entire setup is already impressively efficient from the factory. When I replaced the water pump on our 250, I noted that there seemed to be more coolant in the lines than in the block, and I bet the lion's share of coolant is stored in the radiator, though someone who's actually drained the fluids on these things a couple times would be better qualified on that assessment.

I'm unaware of the existence, or market for, an upgraded radiator for the 2IS. If you're running hotter than you want, I'd start with cleaning the fins on your existing rad, check the fan function, check the thermostat for function, check the water pump for function (they get noisy when they go), and flush/refill the coolant. After all that, if I'm still hotter than I want, then I'd start playing with thermostats, but I sincerely doubt--unless you're tracking your car in the desert or going for top speed records--that lowering your coolant temps via thermostat will render noticeable results. I'm willing to be wrong there, though.

Although, you did just inspire me to start tracking coolant temps in the name of learning the engine's knock retard system...

 

Thanks for your input! To jump back a little I was seeing the temps rise at the end of last summer when in stop and go traffic on hot days. This spring I did a coolant drain and fill and all was good granted it hadn’t got as hot as the the days last summer I was having issues. Last wed we had temps in the upper 90s I ran a couple errands and left the car running with the a/c on while I ran inside. On my way home from the last stop I noticed a coolant smell, saw smoke/steam coming in through the hvac vents and noticed the temp gauge was on the high side. When I got home I popped the hood and noticed a bit of coolant on the driver side between the radiator and engine. I'm going to pressure test the system in the next couple days to see if/where I have a leak and test other cooling system components. How would I be able to test the thermostat and water pump? Heat coming through the hvac system should indicate that the thermostat is open right? Note this is a high mileage car at 204k miles and I don't have records from before 177k

 

When our water pump went, there was a rattle coming from the front of the engine. Sure enough, the factory pump had egged it's snout out and was spitting some coolant out from time to time, gathering in the pan under the engine.

As for the tstat:

 

I have never seen steam in the cabin for the exception of moisture on the evap core that got heated. That said I suspect a hose or heater core leak. You check the floor boards/carpet for moisture?

A small leak leads to low coolant as the system won't form a vacuum during cool down and thus, NOT refill the block and then they overheat.