Hi all,

I am trying to chase down an erratic temp situation which you can read on my original post:

https://landroverforums.com/forum/di...diators-68041/

I changed to a genuine 180-deg thermostat one year ago. Everything had been smooth sailing for the past year (stable 188- to 194-deg temps). Recently encountered some slight overheating over the past few months. Temp rises up to around 210-deg when cruising at highway speeds or when the engine gets hot. I have checked and done the following:

* Infra red thermometer shows 25-deg to 35-deg differential between top and bottom section of radiator (i.e., radiator is not blocked?)
* Replaced water pump, gasket with light RTV which was showing some slight leakage at weep hole
* Replaced with new viscous fan clutch
* Checked and no leaks in hoses
* Reflushed and drained radiator and engine, new OAT-inhibitor coolant, properly bled the cooling system, new brass bleed plug. I made sure to bleed by turning on full cabin heat. No water sloshing sound in heater matrix system
* A/C fans come up when the engine is warmed up and A/C is turned on

I am still showing the same slight overheating after doing the above. I am wondering what's next:

(1) Could it be the 180-deg thermostat needs replacement as it may not be opening fully after the engine is warmed up? Any thoughts on the longevity of the thermostats? I guess I may have to take the thermostat out and do the oven/hot water test to visually see if it would open at 180-degree.

(2) I am still using the original serpentine belt as it does not seem to be slipping.

I hate to keep throwing parts at it. Any ideas from the wise forum gurus?

 

You can always test the thermostat if you have any question on it

 

you clean that thing out? between ac and coolers and radiator, no debris in fins?

 

Yes, I forgot to mention that I cleaned out the a/c fins and radiator fins.... including un-crimping a few tiny cooling fins which has become stuck together.

 

Well, all clean and still a bit warm at highway speed, no air in lines, and coolant in resivoir.
Focus on clog in flow.
1.gunk busted loose from flush
2.stat clogged or not functioning properly. (no real life expectancy, varies)
3. Debris in hoses from work you did (I pulled a piece of that plastic tee out of my radiator, it broke while tightening hose clamp)
Maybe rtv clump on the stat

 

Make sure you are building pressure and the cap is working.


By the way, I know everybody says to turn on the heat for a bleed but practically every vehicle has constant flow through the heater core these days. Older vehicles used to have a bypass valve on the heater for diverting the coolant but now they use a diverter on the air flowing through the heater. Coolant bypass valves were problematic and having stagnant coolant sit in a heater core for half the year was a bad idea also.


Anyway, you don't have to crank up the heat on a hot day just to bleed the cooling system.

 

I recently did a 900 mile trip and noticed temps were getting hotter than typical too. My observations were that it went up to 199 when going up hills. However it also got cooler than normal when going down hill. So a wider swing was observed, by about 6 degrees each way. On a long downhill stretch in Idaho when the outside temp was over 100 I noted a coolant temp of 178!!

One thing different was this only happened when the ambient temp was above 95 F. Note I have the LR 180 stat, but the original radiator which has had green coolant since 39k. (now 159k)

Also noted that I had to clean the bugs off the windshield several times. I assume they were piling up on the radiator too so near the end of the trip I stopped at a self serve car wash and sprayed off the front of the radiator. Since I drove the last 200 miles in the morning when it was below 90 the temps stayed in the normal range of 188.6 to 194 on the freeway at 70 - 75mph.

I don't know if it is normal for the 180 stat to behave differently when ambient temps are over 95 or not, don't get to see that so often in Seattle but I don't recall it happening before. Maybe it was the bugs or possibly my old radiator which needs replacing anyway due to the small leak in the upper drivers side corner.

 

Did you have your A/C charged? That will increase heat output from the condenser and make the whole cooling system hotter.

Are you towing? That will make the transmission cooler hotter and flow into your cooling system.

Is your AUX fan coming on at 212F? It should and it should keep you below 212F at idle no matter what.

 

so your seeing a 25-30 degree difference across your radiator at idle?

 

+1, I also didn't fully understand that line.