[phzimmer]

We experienced 2 instances of engine overheating due to sudden radiator leaks on 2 different 08 Siennas. At the time we were not watching the temperature gauge closely enough and there were no other signs of overheating problems while driving. Both times the engines were toast.
Can anyone recommend a kit that would alert the driver with a warning light coming on when the engine temperature goes up dangerously high? Have not been able to find one online.

 

[floridanative]

Wow, what bad luck!

You can use a Bluetooth OBD reader and a smartphone to monitor exact coolant temps. You can set alarms in the app to activate with visual and/or audio alarms at certain temperatures.

This is the OBD reader I use in all my vehicles (I just leave them plugged in all the time):

Veepeak OBDCheck BLE+ Bluetooth... https://www.amazon.com/dp/B076XVQMVS?ref=ppx_pop_mob_ap_share

In our 2007 Sienna, I also use a short extension cord so it doesn’t stick down into the footwell:

ARTECKIN Full 16pin OBD II OBD2... Amazon.com

I use both/either Torque Pro (Android) and Car Scanner Pro (iPhone) on the phone. Both are worth the few $$ for the Pro versions and both will monitor the temps and set alarms.

This is what my Car Scanner Pro dashboard looks like for the Sienna.

-Mike

 

[sixto]

Our ‘04 overheated a couple of times which we caught by AC not cooling. We always have AC running so it’s easy to monitor.

The OBD solution is elegant but requires a device to monitor. An alternative is to use a trip switch for an auxiliary fan to trigger an alarm in the cabin. These switches come with probes that thread into the cooling system, get strapped to the lower radiator hose or poke between radiator fins.

These systems rely on coolant. If the engine overheats because of sudden coolant loss, you’ll lose the engine before any alarm goes off. You need something like a cylinder head temperature system.

Sixto
‘04 LE FWD 198K miles

 

[sixto]

There’s something like this which isn’t as neat as having all the features floridanative has but if the audible alert is loud enough, you can tuck it under the dash if you don’t like having one more thing to look at.

https://www.amazon.com/AUTOOL-Charg...659043263&sprefix=obd+engine+,aps,111&sr=8-15

Sixto
‘04 LE FWD 198K miles

 

[ericreyn]

Replacing the radiator at a set point in time ( mines due now) seems to be the preventive approach.
120,000 miles or so is what I have figured is the limit. I am at that now. It seems ridiculous to replace a perfectly good radiator but they seem to fail quickly and with little warning.

 

[sixto]

Do they? We had mysterious coolant loss for months if not years before I found telltale pink crystals in the radiator. It’s the plastic thermostat housing/pipe that failed without warning.

But, yeah, replacing the radiator is an unpleasant prospect on the side of the road or even in a parts store parking lot.

Sixto
‘04 LE FWD 198K miles