ACDelco thermo switch

[Iceni John]

I have an ACDelco thermo switch 6402920 on my passenger-side thermostat housing, connected to a red "Hot Coolant" warning light in my gauge panel.   I tested it this evening and it works  -  however, I'm not sure at what temperature it turns on the light.   ACDelco's website doesn't even show the 6402829 as a current product, and PCI doesn't list it either.   An eBay listing of one of these switches shows "AC215M" stamped onto its body  -  is it therefore a 215 degree switch?   Does that sound right for a DDEC 6V92?

I've never had this warning light come on, but I had the DDEC amber CEL come on once when I almost overheated last year, so I think the CEL is triggered at a lower temperature than the "Hot Coolant" light.

Thanks, John   

[chessie4905]

If you "almost" had the light come on, it might be a good idea to install a set of misters. Cheap insurance. Also assuming your cooling system is in good condition.

[chessie4905]

If you "almost" had the light come on, it might be a good idea to install a set of misters. Cheap insurance. Also assuming your cooling system is in good condition. I know that Napa used to have a thick catalog that listed various sensors and their temp triggering point. This info may be avail online with some searching.

[Oonrahnjay]

If you "almost" had the light come on, it might be a good idea to install a set of misters. Cheap insurance. Also assuming your cooling system is in good condition. I know that Napa used to have a thick catalog that listed various sensors and their temp triggering point. This info may be avail online with some searching. 

     Good point, Chessie but John has completely rebuilt his cooling system in the past few months.  He's put in new radiators, water pump, fan and fan drive, etc.  He posted about testing on hills in hot weather with NO issues so I think that it's a good guess that his system is in good shape.  And considering the timing, it would also appear that the light "almost" came on when he was dealing with his old, deteriorated system.  I think he's trying to work out his warning system for the future.
     Your principle is very valid -- we need to do everything in our power to avoid overheating engines and make sure that every warning/overheat prevention system is working properly all the time.  Even the "good" cooling systems can suffer a temporary or sudden problem that could kill an engine in seconds.

[luvrbus]

The light is triggered at 205* and shut down is 215* the DDEC is a remarkable animal when the light comes on @ 205*it reduces the available HP trying to help save a engine   

[Iceni John]

If DDEC warns me at 205 degrees and shuts down the engine at 215, there's little point in also having a maybe-215 "Hot Coolant" light and buzzer as well.   At 215 degrees my engine's toast.   I think I'll repurpose that 1/2" port in the thermostat housing for something more useful.   (Like what??)   I've already got some mechanical temperature gauges for each side and for the radiator outlet, but I'm sure I'll find something to put in there!

Thanks, John