Checked the voltage with my handy WalMart cigarette lighter volt meter. 12.5 volts without the lights on. That's not good... Ordered an ultra-gauge last night.

 

Swing by a parts store for a free charging system test. Alternators are three-phase generators, they have separate windings and diodes to make DC out of AC. So if a few diodes are blown, you can have a 120 amp alternator turned into a 40 amp alternator. If running, the Wal Mart tester should show above 13.2 with everything that came stock on the truck turned on (lights, wiper, AC, etc.).

 

Update... Got my Ultra Gauge last night & kinda set it up this morning (thinks I'm getting 1361 MPG's & haven't figured out how to correct that out yet ). Okay, the temp (after warm up) runs a consistent 188.0 @ 55MPH, rises to 192.1 at 45 MPH, but in traffic & speed somewhere between 0-30, the ultra gauge reads between 195.6 & 215.6 depending on speed & distance between stops. I let the truck idle at the house & watched the gauge till it got to 220 degrees, but even with 15 minutes of idling, it never passed that 220 degree temperature on the ultra gauge (well, when I turned the Discovery off, it went to 224 degrees for about 3 minutes & dropped to 221, etc. however, the factory peg (dash) gauge was just all over the place 212 degrees can be in the middle or clean at the red. I also noticed the electric fans are not turning on as they used to. With the AC on, they run fine & can hold a paper towel to the grill, and I know at one time they would come on if the temperature got to a certain level, as was the case when I bought it because they would still run after I shut it off for a few minutes & shut off by them selves, but they are not doing that now... I looked but couldn't find the panic temperature where bad things begin to happen? As I said, I know they work, but what temperature should the fan turn on due to temperature? Is there a separate relay that handles them coming on for additional cooling?

 

My D1 will run in today's temp from 183-187F. I have a 180F stat. You may want to look at radiator being sludged up. The temp will be lower on bottom rows, by more than 10F, from top rows. You can get it rodded out.

 

LR radiator is just rebuilt. New LR thermostat, new hoses, new LR sensors, new antifreeze, Didn't change the fan clutch, but it feels like peanut butter when cold, roars for about 1/4 mile when I start to drive, and spins about 1/4 turn & stops when warm. So, your temperature never goes over 187 degrees? At what temperature do your cooling fans come on w/o the AC on then? Is 220 terminal?

 

I don't drive without AC on, so have not monitored that. 220 is not terminal, but it is not right. My temp will go over 187 when driven and slowed down, but stays under 200 at idle. Spring for a $10 180F stat. Check the serpantine belt route. Be sure stat has spring end inside the engine block.

 

Radiator, thermostat, hoses, sensors, & coolant are 2 weeks old. All new LR parts (-) the rebuilt radiator & professionally installed. Found one of your old posts that talked about the ECM turning the fans on at 230 degrees (or something to that effect during a search) I did have to leave it idle for a really long time to get the 220 degree thing to happen. As I said 195-215 degrees is the norm in stop & go traffic. Since the radiator was rebuilt, could I have been taken & they just painted it?

 

All radiators obey the same laws of physics. They have to radiate the heat. With truck warmed up, engine off, measure fin temp from top to bottom on a vertical line. Should be no more than 10F difference. It is about 5 F on my rodded out D1 radiator. If clogged up, lower rows will have less coolant flow and lower temp. If serpantine belt is routed wrong and fan blades reversed, you could have problems.

 

Thermostat can also be "bad" and not opening at correct temp, you can test in a pot of water on the stove. If the thermostat was slid over to the side when mounting, it may not leak, but will allow water to always flow, instead of staying in the radiator long enough to cool off. Usually shows up as coolant temp under the rated stat temp at 30 - 40 mph. Again, the spring end of stat goes inside the block.

 

Taking it back to the shop today. See what they can find.