Installed water pump and 160 thermostat today

[pedot99boxster]

Originally Posted by JFP in PA

Yes, we have seen this both on cars with full instrumentation (after market coolant and oil temp gauges), but have also seen it using PID scanners as well.

The steady state I refer to is the equilibrium temperature the car settles at when running at a steady highway speed (50-60MPH) on an average day (say 68-75F air temp). I think that you are overlooking the heat transfer capacity of the cooling system in these cars, and the throttling effect of the stats; stuck in traffic, a car with a 160 stat will eventually get warm and kick the fans on, but it takes longer than with the 186 stat. Once either car gets moving, both will settle back to a steady state condition, with the 160 stat car settling at a lower temp (usually around 175F or so). This is the impact of the heat transfer capacity of the cooling system. But the car with the 186 stat settles at a much higher temp, often north of 210F. If you put both a 160 stat and an 186 stat in a beaker of heated water as I mention earlier, you would note that at around 170F the 160 stat is wide open, while the 186 stat is still closed. As the water gets hotter, eventually the 186 stat starts to open, but is not fully open until well past 200F, restricting the coolant circulation up to that point; so it is "throttling" the coolant flow. So even though the car has the capacity to transfer the heat out of the engine at steady state, the throttling of the 186 stat restricts the coolant flow and keeps the coolant hotter at the same speeds and air temps.

The inaccuracy of the dash display is actually two fold; it is inaccurate across much of its "band width", but it is also non linear (it does not "sweep" equal amounts for an equal amount of coolant temperature change). On a car showing 180 degrees on the dash, it is not unusual for a PID scanner to read 210F, yet both the scanner and the dash are getting their information from the same sensor in the engine. In essence, the temp display is little more than a "not over heating/over heating" idiot light replacement.

Hi, i believe my water pump on my 986 is bad, lost allot coolant last friday temp. indicator was blinking, checked underneath and suspected the water pump, there's allot of stain around the hose under the pump. pressure checked it to about 10-15 psi but no leaks visible. also noticed when the engine temp get to about 186 deg. the engine blower doesn't come on then about 200 deg. the radiator fan on both front comes on. thinking about doing this water pump and thermostat replacement on my own. did you have to remove the front engine mount to replace the water pump?
where did you get the parts?
Thanks
Ferdie

[JFP in PA]

Originally Posted by pedot99boxster

Hi, i believe my water pump on my 986 is bad, lost allot coolant last friday temp. indicator was blinking, checked underneath and suspected the water pump, there's allot of stain around the hose under the pump. pressure checked it to about 10-15 psi but no leaks visible. also noticed when the engine temp get to about 186 deg. the engine blower doesn't come on then about 200 deg. the radiator fan on both front comes on. thinking about doing this water pump and thermostat replacement on my own. did you have to remove the front engine mount to replace the water pump?
where did you get the parts?
Thanks
Ferdie

We are a shop, so we have parts deals through multiple sources. While removing the engine mount is not necessary, many doing this on the ground find it gives them better access.

[pedot99boxster]

Hi, i believe my water pump on my 986 is bad, lost allot coolant last friday temp. indicator was blinking, checked underneath and suspected the water pump, there's allot of stain around the hose under the pump. pressure checked it to about 10-15 psi but no leaks visible. also noticed when the engine temp get to about 186 deg. the engine blower doesn't come on then about 200 deg. the radiator fan on both front comes on. thinking about doing this water pump and thermostat replacement on my own. did you have to remove the front engine mount to replace the water pump?
where did you get the parts?
Thanks
Ferdie

[pedot99boxster]

bad water pump?