What thermostat should I use for a 97 D1? Also where in the rave can I find how to replace the thermostat?

 

Any auto parts store should have your Tstat in stock. The gasket is a different story but there's a Chevy Tstat gasket that works just as well, can't recall what make/model though. Or just buy the Tstat and Gasket from Rovahfarm.com
I prefer a lower Tstat, like 180* and one that will fail OPEN
-Remove radiator plug, siphon out ~a gallon of coolant.
-follow the upper radiator hose to the engine, remove hose clamp and pull hose off nipple
-remove two bolts holding nipple to engine
-remove and replace gasket and Tstat, paying attention to Tstat orientation Jiggle ball goes up
-reverse previous steps.

 

Don't just go in the auto parts store and ask for one for a discovery, you'll get a 195, which is too hot.
Good thermostat and gasket PN here: https://landroverforums.com/forum/di...rmostat-51327/

 

Spring side of t stat goes towards engine block.

 

Spring side goes toward block, and any jiggle device or vent hole goes at the 12:00 position to let steam bubbles pass. About a half a gallon of coolant will be spilled. A scanner that shows live data (like an Ultra Gauge) is a great improvement over the factory heat gauge.

Consider that in the days of old when our Buick based engine was new (early 1960's) that it was not uncommon for guys to run a winter and a summer thermostat. I would have to admit that guys in the frozen north would appreciate a 192F stat in wicked cold weather of late.

If you are swapping coolant at the same time be sure to spend some time reverse flushing the radiator and the heater core.

Page 366 of 873 in the D1 work shop manual is pretty close, but the 97 won't have that electrical connector shown.

 

The downside of the higher tstat is head gasket replacement becomes more frequent without overheat occurring. 5 years, 18mpg average (better atomization, lower cylinder carbonization with the lug torque LR fuel map) and it's time to finally change to the lower fully open temp. My gaskets are failing at the back two siamesed cylinders - 5/6. It's not my mechanical ability, I'm all about the details and have allot of experience with Rover HG's (on other folks trucks). There's no doubt in my mind the block should be decked (line bored too) but I don't have the time to take the truck off line being my dd.

Yes, it's nice and hot once the tstat is open but it takes too many miles in this single digit weather until there's heat available and the motor will not perform well until it's fully open (throttle plate heat). Because ice forms on the inside of my windscreen just from my breath it literally sounds like it's going to explode when I go from defrost to cabin heat. It has a time or two made a loud "BOOM". It's that cold out. The lake I'm on makes the same "BOOM" sound when it's contracting.

 

In the days of carburetted engines, when people ran different winter and summer temp thermostats, the manufactures, like Land Rover, specified a winter and summer temp.
Land Rover only specifies one temp for the D1, 88c. The closest you can get in the US, without getting an 88c from a dealer or Rover parts house, is a 180f.

 

The gasket is everywhere too...Felpro 12994.

The gasket fits a ton of older cars.

Click on the "Compatibility" tab.

Fel-Pro 12994 - Water Outlet Gasket | O'Reilly Auto Parts

 

Is this the right thermostat?

 

Yes, but you can also get one from most parts stores...

List: Thermostats - 1998 Land Rover Discovery | O'Reilly Auto Parts

Thermostat | 1998 Land Rover Discovery 8 Cylinders 2 4.0L MFI OHV | AutoZone.com

I have heard you should stay away from the failsafes.