Finally got around to swapping out the coolant and thermostat, dexcool was in it and service records indicate that at least relatively early on in its life it was swapped out regularly, but who knows how long ago the last change out was as the records fade fast. I flushed it with distilled water and Prestone flush/cleaner before flushing that out, swapping out to a 180F (or so I'm told...) thermostat and filling it with Prestone and a bottle of water wetter. Before I was running 195 on the highway and up to 211 stopped at the lights in town, the 211 seemed a bit too high for me, I'm not fond of needing the aux fan to turn on in everyday traffic. Now I'm running 193 on the highway and 204 stopped in town- I'm going to call it an underwhelmingly mild improvement. The t-stat I used was the motorcraft one from autozone and although it's labeled as a 180F, I'm not entirely convinced it is given the temperature patterns. My gut tells me I should have put the water wetter in a while ago and seeing just what that would have done as I'm not sure my efforts really did much (other than get the dexcool out).

I've bled the system the last two mornings before taking it for a 30 minute drive and plan to do so for the next few days to make absolutely sure I get all the air out. Long term plans are to leave it for now and go with a different t-stat next time as the temps aren't alarming.

 

Where did you purchase the thermostat? Similar discussion here: https://landroverforums.com/forum/di...e2/#post727747

 

Your temps are bang on Enjoy

 

Isn’t water wetter for water ??
it doesn’t do much as far as cooling effect Trust me I tried


WaterWetter is a unique wetting agent for cooling systems which reduces coolant temperatures by as much as 30 degrees Farenheit . This liquid product can be used to provide rust and corrosion protection in plain water for racing engines, which provides much better heat transfer properties than glycol-based antifreeze.

 

You can add it to water/antifreeze mixes as well. It's my understanding that it works by improving the ability of the water to adhere to a surface (the so called "wetting ability") and therefore improve heat transfer. I'm not 100% convinced but thought I would give it a try. I was a very bad scientist about it, changing 3 variables (water wetter, t-stat, and coolant) and then wondering which one is effecting my system. Ultimately I'm satisfied with my temps and I'll probably report back in a few days with any updates.

 

We just had a big discussion of thermostats in my inline thermostat mod thread and I would say that 204 is below the max of what most people experience with the 180 degree OEM setup. Many people, including myself, saw temps up to 208+ at idle with the stock setup and 180 degree stat. Some people are able to see idle temps around 195. Maybe they are excellent bleeders, got a cooler thermostat, or some other aspect of their truck is running cooler somehow.

I think chasing lower idle temps than 204 with the stock setup is a fools errand. I tried for 2 years and gave up and went with the inline mod. Keep in mind that the stock temps for these Discos was around 230 at idle so you are doing better than that. Although I like the inline mod, there is no evidence that running at 190 instead of 204 at idle is necessary or beneficial. It stands to reason that a decrease in temperature and reduction in fluctuations would be a good thing but we don't actually know that.

 

the stock set up idle 230 degrees when you shut off engine that coolant gets even hotter
no wonder these engines had high failure rates

 

I have a 177k mile 2004 that I've owned for just over 2 years and have driven about 10k miles. I've drained and filled the cooling system multiple times, at least four and always with Dexcool at 50/50 concentrate, most recently in early March after having the engine out for a refresh. I installed a new water pump at that time. In 2018 at about 170k I put in a 180° degree thermo (gray body) from Lucky8 and then a $60 delivered Ebay radiator about 1,500 miles later. I've never had an issue bleeding the truck, never parked it on a hill with the nose as high as I could get it or dismounted the reservoir tank, never spent days filling thimble-fulls of coolant through the T, never fondled the hoses trying to burp it or hired a shaman for a cleansing ceremony. I'm not denying that people have had their share of issues or claiming that this whole scenario is fiction, but I think it has more to do with a problem with the particular vehicle in question or the process being done incorrectly somehow. Or maybe I'm just lucky over and over, which I strongly doubt. For what it's worth, this reality does exist.

The only thing I do differently is I fill the system through the reservoir without the two hoses on top of the thermostat attached. Once coolant starts coming out of the thermostat I connect the two hoses. I think this helps get all the air out of the radiator, since you're filling it from the top down. Then I remove the bleed screw and slowly fill the reservoir until it's up to the mark on the side, finally topping up through the bleed screw itself. The last time I had to add a bunch of coolant through the bleed hole until it was full since the engine was completely dry. I start the truck and turn on the heat, adding coolant to the tank as required. After about 10 minutes I get heat. Done. One anomaly this last time was that I couldn't get the level in the reservoir to stay at the mark. I would smell coolant under the hood and fearing I had a problem I would add more to the tank. After a couple days of the level continually settling to the tape mark I put on the tank, I gave up adding fluid and just drove it. The coolant smell went away and the level hasn't moved in over 1,000 miles.

Here's a graph of the last 130 miles in the truck that I compiled from the OBDII output. It was about 5 or 6 trips over the last week that I stitched together, and the dropouts in the red line are I where the breaks in travel were. This graph is combined stop and start driving, a couple highway jaunts, back roads, etc. There are over 15,000 data points in the graph and the median number is 188.1° with a peak of 199.4°. Most times when I look down at the gauge in OBD Fusion I see 190°-194°. The one variable we haven't seen in this is the summer weather in Philly. I'm sure that will raise the temp a few degrees when sitting still and the pavement is 135° instead of the 50° or so it is now.

 

The longer you idle the more your temps will rise. Nothing will ever change that. Airflow thru the radiator is drastically reduced at idle. You could come off the freeway where you've been running 188-193 at 65MPH for 7 hours straight, stop for a quick bite at MCD's and while in line it would be 193, 195, 198, 200, 202, 204, 206, 208, 209, and possibly all the way up to 210-215F which is totally within the temp range they were made to handle. 99-04 D2's rolled off the line doing 220F at idle no doubt about it probably up to 230F, but Ultra Gauge, ScanGauge, or any OBD2 bluetooth device = DID NOT Exist!!!!!! I had 2 03's and I got 160/189K out of and never touched a single HG on either one. Age of our D2's is not getting any younger, and unless you've had it new from 99-04 most everyone's D2 is 2nd, 3rd, or 4th hand (if you're lucky) so who knows how it was maintained up to that point??? Was the coolant ever topped off during a TBH plate leak or was it even noticed? Did they put the proper antifreeze in it and not have issues with two different types mixing??? Was the system ever flushed? Was the 20 year old thermostat ever changed??

So many things can be factors, but I guarantee once you roll out of MCD's the engine temps would eventually creep back down. If you had a newer Hayden 2991 fan clutch it would probably engage until you speed up to help quickly cool it down. The #1 thing you want to do is monitor your temps NEVER rely on the gauge!!! Get an actual live data temp reading!! Then #2 you want to see if when it starts to climb if it goes back down. I personally monitor it, but up until the 210F range I'm not even worried. Then say if I get in the 215F range I'll slow down, or just watch it, and if it goes past that pull over and investigate, but if the temp drops you are perfectly fine. D2's have temp swings. They'll start out 182F, 186F, 188 to 193F, and then it could hit 202F cruising at 65-75MPH, but on a good condition cooling system it should then level off, and drop back down into the 188-193F range.

 

Not that my .02 matters as I've only done this procedure once but was this past weekend.

I pulled the lower hose and let it drain.
Put the hose back
Bleed screw removed
I used a board under the overflow to help hold it up on top of the battery box cover.
Filled with distilled water until it was coming out of the bleed screw hole - still showing coolant initially.
Plugged that up and cranked the truck and let it run with heat on high for a few mins.

Repeated the process above through 7 gallons of distilled water until pulling the lower hose showed clear water and liquid coming out of the bleed screw was also clear.
Topped off with a gallon of concentrate - which reminds me, I need a little more.
What I've read was that draining from the lower hose then filling with concentrate puts the system at about 50/50 mix.

I had zero issues - no re-bleeding or adding coolant in the bleed hole.....
PO had a 180 thermostat installed and I idle at 185 regularly - I've only seen over 200 when on a long grade uphill heading to the NC mountains in the summer at 70mph.