What are the reasons the temp gauge will barely ever hit halfway? Its about 20 degrees here in Ohio but even after driving 15-20 mins it still wont halfway. The heat as well does not blow nearly 90 degrees when set to it. Also, with new spark plugs, spark plug wires, fuel filter and pump, sometimes my car will only start on its second crank. Bad ignition coil?

 

Probably has a thermostat stuck open. As for not starting first time, that could be a number of things. Start with checking thermal time switch wiring and operation-make sure grounds are clean and making good contact. There is a very good link on cold start diagnostic if you look back through some threads here. I don't recall thread title but believe it was in jag lovers. Maybe someone else can chime in

 

Gotcha, the car never hits halfway and when it does it goes back down a hair. The heat works but doesn't blow nearly as hot as usual. Can that rule out the cts?

 

And do you know exactly where the thermostat is in these cars? series 3

 

They are right under the thermostat cover that the arrow is pointing to in the picture.

I just grabbed a straight six engine picture but I am sure yours won't vary by much.

Not sure about access since I don't have a six.

Also, are you absolutely sure your coolant is topped off in the radiator? Not the overflow tank, but the radiator.

Other problems could be valves that allow engine coolant to enter the cabin heat radiator binding, not actuating. I am not sure there are any in your car, but what little I know about Jaguar, they over engineer. If they can put a valve in, they will.

Also, on lots of cars there is an air blend door that flaps back and forth under your dash. Turn on the air conditioning it flaps closed the heat side and vice versa. If you are stuck on the "summer" side, you are up a creek until you get it freed up or get an actuator.

An easy trick is to warm the car as best you can (take a drive) and turn the heat on full. When back home, grab the heater (coolant) hoses that go into the firewall and check if they are close to being very warm - both in and out hoses. If both are warm the air flapper thingie may be stuck.

 

Forgot pic

 

Test #1: Charge your battery overnight. Get it real angry and ready to serve. See if it takes two starts.

Test #2: Turn your key to on. Listen for the fuel pump to run for a second then shut itself off. Turn key off and then on again and listen again. Then start. See if it takes two starts.