Morning fellow Disco drivers. I’ve got a daily drive ‘03 with an Atlantic British top hat motor. It was installed around 2010, two owners ago. The past two owners have been Land Rover techs.

I’ve been consulting @Extinct on my temperatures and we’re both kind of stumped at this point. I’ll preface this all with the fact that the truck does NOT overheat, loses no coolant, throws no codes, and runs extremely well.

the issue:

• High running temps. When it’s over 90 degrees out, and the AC is on my coolant temps run 188-203. That’d be excellent for a factory thermostat, I’m running the Extinct Inline with a 180 thermostat.
• I live In Birmingham, AL. It’s very humid here so low air density in the summer + very hot weather.
• Interstate driving, temps stay 194-203 cruising 65-75mph. As expected, more engine load = more temp. Most of the time up hills it hangs in the 195-201 range. It comes back down to 190-194 cruising down a hill.
• Around town temps usually stay below 190 even in 95 degree weather IF I stay moving. If I get stuck in traffic, or idle a bunch, temps rise to the same level the run on the interstate and stay there (194-203)
• I’ve yet to see it over 203 degrees.
  
• It just seems like it gets to a point where it can’t reject any more heat. I realize it’s not overheating. I’m fine accepting the fact that this is a non issue, I’m just very confident It should be staying around 100 degrees over the ambient temperature.
  
• Ive tested without the thermostat element, temps are the same. Maybe 1-2 degrees cooler (probably just do to less flow restriction from no thermostat element).
• Without the AC, it stays much much cooler. Temps are what I would expect when the AC is not running (100 degrees over ambient temp on the nose). The AC compressor is new (replaced a year ago).

​​​​​

recent maintenance and replaced parts

• This truck was very well maintained. I bought it because 1) Top hat motor and 2) it was already a daily driver.
  
• coolant hoses are all less than 2 years old.
  
• it had Dexcool in it when I bought it. But it had been flushed recently. I know Dexcool has a bad reputation but to my knowledge the more recent formulations do not cause sludge buildup.
  
• I replaced the radiator in response to these temps a few weeks ago. I ran water through the system and switched to the coolant I had on hand, BMW blue coolant.
  
• there’s no air in the system. I bled it with a power bleeder we had on hand (I’m a part owner in an motorsports focused shop).
  
• I replaced the coolant bottle cap. The seals had started deteriorating.
  
• i assume the water pump is new/ came with the AB motor. AB motor only has about 25k miles on it.
  
• Extinct Inline thermostat kit with 180 element.
• Fan clutch is original but works fine/ has lots of resistance when hot. Plus that wouldn’t help interstate temps anyway.
  
• I have a factory brush guard that blocks off some of the grill. I removed it, tested back to back with and without. No change in temps.
  
• As mentioned above, it loses no coolant, doesn’t smoke or misfire, doesn’t throw codes, and has no noticeable coolant leaks.

So, any thoughts? Am I being too particular? Should Injust be thankful that it runs well and stop over analyzing things?

Or, is there something I haven’t looked into? Has anyone else had similar temps?

Note: In cooler ambient weather it never gets this hot. It stays under 190 ALL the time with temps below 80 degrees or so.

​​​​​​​Any thoughts would be great. I’m also happy for you to tell me to kick rocks…

 

My 04 with a Turner engine runs the same way. Almost the exact temps and scenarios you mentioned. The whole cooling system was replaced 25k miles ago with the motor install. Extinct 180 inline kit and HD fan clutch. I wouldn't worry about it at all. As long as you are under 200 90-95% of the time you are golden.

 

You may have some debri build up in block, disconnect hoses from top and bottom of block , block the bottom outlet and pour some radiator flush into block from top , let it sit for a while then flush with garden hose with lot of water in both directions few times until its perfectly clean,( if you can open drain plugs on block even better), but don’t sweat over it.
i used to drain and flush the block every 2 years & even though my temp was always on cool side and I had inline t-stat setup , I would immediately notice a few degree drop in temp after flushing block,
if you have not done that recently then try it out.

 

you're fine. that is a bit higher than me (nashville) but it's not excessive. Certainly better than mile 1 on these trucks when new.

 

Sounds similar to what I experienced and mentioned in this thread on my old Disco a while back: https://landroverforums.com/forum/di...highway-84061/

What you are describing is, in my experience, "normal" for this engine and cooling system with the inline mod, etc.

That said, compared with other vehicles I have experience with, I still don't like the variability of temps with this cooling system, even with the inline mod. I'm playing around with other options for my newly acquired Disco.

 

Here's an issue I haven't seen mentioned yet...at one point, I found that my A/C condenser fan was seized, and the condenser coils behind it were clogged, causing my temps to rise while Hwy driving. Basically, the fan and clogged fins were causing an air flow restriction to my radiator, not allowing it to do its job at 100%. I replaced the fan motor and cleaned out the condenser fins, and the problem was fixed. Here's a cheap way to replace it, https://landroverforums.com/forum/di...option-112156/

I also replaced the clutch fan with an Electric unit, and my temps are much more stable now, but that may be more than you are looking to do, if not, check out this thread. https://landroverforums.com/forum/di...fusion-112185/

 

@Mntnceguy The condenser fan is working properly, it spins freely. One of the first things that I checked - I had that issue on my last Disco. Great thought though.

I have not replaced the fan clutch, and while that won’t fix my highway temps my guess is a fresh clutch will help temps stay lower around town for sure.

 

Good thought. I did a coolant flush when I swapped out the radiator but didn’t think to flush out the block.

I think the truck did sit for a while after the AB motor was installed. Maybe some coolant built up during that time and is causing some slight clogging or something.

 

Gotcha. Good to know. It’s under 200 95% of the time for sure. I can only get it to 200 on a long uphill on the interstate, and climbing the hill to my house (low speed neighborhood road, super steep long hill). But it usually won’t sit around 200. It’ll get up to 203 at the most and float back down to 194 pretty quickly.

 

You're absolutely fine. Don't even bother messing with it. In a perfect world, I wish mine ran at 194 all day long. No more, no less. That would be ideal. Mine like yours, can run from 175-203. Depending on load, AC, outside temp, road grade, speed, etc. I've flushed, replaced coolant, tried different thermostats, cleaned condenser fins, etc. No change. I've finally stopped obsessing over it. As long as it's under 210, it's fine.