An interesting observation which I would like to share... as well as a puzzle....

I changed to a new radiator, water pump, 180-deg thermostat, temp sensor about a year ago. My temps according to Ultragauge was 188-deg to 194-deg (cruising) and up to 205-deg (idling at stop light).

1) The headgasket blew a week ago. I took it to a reputable independent LR shop to get the head gaskets changed. The shop was not familiar with the 180-deg thermostat. They replaced the headgasket, machined heads and also changed to a new 192-deg thermostat. I collected the car upon completion of the job. Drove her for a week. Ultragauge is now showing 205-deg to 215-deg (cruising) and up to 221-deg (idling).

2) I subsequently requested a change to the 180-deg thermostat today. Observed Ultraguage showing temps back to 188-deg to 194-deg (cruising) and up to 205-deg (idling at stop light).

As I observe #1 and #2 (180-deg vs 192-deg thermostat, that is 12-degree thermostat opening difference)..... there is a relatively wider delta in the respective coolant operating temps at cruising and idling.

What are your thoughts as to the cause(s)?

 

I have had 2 different auto parts stores tell me they can not sell me a 180 thermostat for my disco as it is not the right one and they can't sell it to me. I went to a different store.

I suppose it is possible that the engine computer may try to enrichen the fuel mix if the engine is not up to temperature, but I don't think 12 degrees would make a big difference, but it could make a difference when it comes to overheating or pressure increase due to temps.

 

I'm not a LR expert, but you really shouldn't be getting the "cold" fuel map at 188+ degrees. That is normal operating temperature (my VW sits at 190, according to the not super accurate gauge, but the middle number on the gauge is 190).

 

Isn't that some kind of violation of a constitutional right, or something?

I've had them say "hey, that oil isn't for that car", or "well we need your phone number for the receipt", or we can't sell you that.

Both are obviously nonsense and I've walked out with the product I went in for.

 

I get the exact same readings from my 2003. I'm currently attempting to find the issue behind that 6-8 degree spike up to 203 when coming to a slower speed or stopping after a good drive. If one of these stores has a loaner infrared heat scanner then I'm going to start with efficient radiator cooling then work my way from the condenser to the fan clutch to the thermostat. Everything but the radiator is new but that spike over a few, short seconds can't be normal or good for the motor. Something must be faulty. I have been called neurotic but better for me to be "neurotic" than to neglect small details like this and end up searching for another used motor just like it next year

 

I'd just pony up and get an inline thermostat installed -- I get 185 degrees at the MAXIMUM (sometimes 190-192 in the summer), and no fluctuations in temperature higher than 2 degrees when coming to a stop.

Anything above 200-205 degrees, with the stock engine, is going to eventually get you a slipped piston sleeve. I'm serious.

 

Strange. I'm on a 192 state till I can buy the parts for the in line mod and I run 195-203 all the time, never spike. Of course, I do have an electric fan, but even with the old mechanical I never really went over 205.

 

Far as I know, mr. Slipped Sleeve likes to come to the party fashionably late, say about 215. I haven't put a whole lot of thought into that in-line stat as I still have a problem somewhere in the permanents of the cooling system and I certainly need to rebuild both driveshafts and get some new plugs and wires, then valve cover gaskets before I do anything else. So much for TVs, cool new denim pants or the like on my Xmas wish list. I'm in the process of sending my aunt and grandmother a list that includes Ujoint and RotoFlex part numbers. UGggh!!

 

Haha I know the feeling --- No more ski gear for me, it's just U joints, air springs and meter hoses

But on the real, I'm reasonably certain you don't have to worry about the rear driveshaft, most people just rebuild the front shaft because it's the one with the double cardan joint, AND is close to the catalytic converters so that's what dries out the grease.

If you're willing to try the valve cover gaskets yourself, there's an excellent writeup online - it's just a lot of work, but the work itself isn't really difficult at all.

If you wanna switch up the cooling system, I'd say throw the inline tstat in when you swap out the radiator - it's seriously not crazy expensive, and totally worth doing. Also, throw an electric fan in there too. You will have temperatures that will let your truck run until 200k and beyond :}

 

Just in case you were wondering, LR designed the system to run that hot intentionally, so they could eke out and extra few points on the emissions scale.

At this point running a cooler Tstat wont do much other than prolong the life of your engine and head gaskets.

If we were worried about emissions and mpg we would have never purchased these things!!

On a side note, I know people buying up VW TDi's as they are a steal of a bargain right now... Extra horsepower and more polluting... pfffftt.