My main complaint with the stock tstat setup is this. It heat soaks and absolutely saturates the heads until it opens up. With the tstat closed, there is precious little coolant flow through the block and heads (only the heater core is getting flow, really). Your coolant sensor is right beside the tstat on the LIM.
While the tstat and ECT sensor are seeing about 190* (just before opening of the stock tstat), the coolant that is just sitting still in the heads and block around the cylinders could be reaching 250+. It's just stopped soaking up heat and letting the heads get super hot. If you're viewing the temp on a digital gauge (since the dash gauge is sluggish to react), you can see at the point of the tstat opening the coolant temp spikes as all this super hot coolant comes out towards the radiator. Now, what's worse is in winter after all that super hot coolant is gone it's replaced with super cold coolant from the radiator. This alone can crack parts.
The bottom line of all this... get a drilled tstat, even if it is only stock temp. This will keep coolant from just sitting still. Yes, the car will take longer to heat up (about 50% longer, as I am realizing after installing a drilled Saturday) to full temp. But, to me it's worth it to keep sudden shocks to the system minimal. Can you imagine what it must be like for your engine to have some parts with coolant sitting at over 250*F then suddenly get jammed with -15*F coolant?
Originally Posted by Sabrewings
My main complaint with the stock tstat setup is this. It heat soaks and absolutely saturates the heads until it opens up. With the tstat closed, there is precious little coolant flow through the block and heads (only the heater core is getting flow, really). Your coolant sensor is right beside the tstat on the LIM.
