I'm trying to weigh the pros and cons of upgrading to a 180-degree thermostat that was designed for the Td5 (I have a gas/petrol V8 -- this one: THERMOSTAT ASSY DII & FREELANDER 180 DEGREES FAHRENHEIT, PEL500110, RNQ028 - Rovers North - Classic Land Rover Parts) versus installing some other inline thermostat, where you get a generic t-stat and housing, drill out a small hole in it and install it.

It seems like the stock 180-degree t-stat is a better choice because it's just plug-and-play. Are there any advantages over that for a different setup? I don't understand the cooling system all that well, but as far as I understand it, the coolant travels from the lower radiator hose and then into the engine if the t-stat is open, but if it's closed it goes through the other pipe back into the radiator. I'm not sure if I understand how a different setup would change the flow and make it better/worse.

Any advice much appreciated.

 

Actually, if the stat is open it flows both through the rad and it recirculates still hot coolant, so the plus of the in line is that all the coolant must go through the rad.

 

So let me get this straight -- when you do the inline, you effectively eliminate hose #2 in the following diagram and the T intersection just becomes a straight pipe with a bleeder valve? Discovery II Cooling & Heating - Rovers North - Classic Land Rover Parts

 

Inline
Stabilizes coolant temps. Doesn't work on a bypass principle.

 

Pretty much, but the thermostat also moves to the top hose.

 

Oh, I see. So you essentially bypass the thermostat in its original position, using a new longer bottom hose. Then you take out the T connection and put in a new thermostat and bleeder valve in its place.

 

Another stupid question: the direction of coolant flow has to be from the bottom hose through the water pump into the engine and out the top hose, right?

I'm just trying to conceptualize whether there's any difference in where you put the thermostat.

 

Correct. Heat rises.

You want to mount the thermostat as close to the manifold outlet port (hose) as possible. Your goal here is to measure coolant temperature and meter coolant flow appropriately based off block temp. This is predominantly the most ideal location to obtain accurate readings using a spring / temp controlled stat.

I've been running a 180* in-line for a few months and have zero concerns. If I had to nit pick, I would persuade you to run a 190* in cold climate. It's dipping into the low 20's here in Philly and my 4.6L runs on average 183.2 - heater output is fine, truck heats up to comfortable temp.
I would be more satisfied seeing my temps in the 190-194.0 range, but I'm too lazy to swap in a 190

 

The thermostat has to be in the top hose because the coolant flows in the top of the radiator and out the bottom. Placement definitely matters because if you put it after the radiator then it will get cooler coolant since its been cooled by the radiator, so it will open a lot later and overheat. The only reason the factory rad works there is because of the bypass which puts hot coolant directly onto the stat.

 

Bingo.