I know, that’s why I’m so perplexed. But it has not done this since my cooling system refresh, and I’ve not had the heat on since then. The reason I don’t think mine is the fan clutch either is due to the fact that if I rev the engine to even 1k RPM for 10 seconds or so, it drops. It has always done this a bit, but if I am idling and not moving, that says the fan clutch must be working doesn’t it?

What’s crazy is last weekend when I took it out and played for a few minutes fairly close to the house it idled for probably close to 20 minutes and didn’t get over 195 while I aired up the tires. I’ve also done some non-scientific testing and let it idle in the driveway from time to time and might climb to 197 or even 201 and then go back to 194 or 195. The moment I put it in gear before the end of the driveway it’s at 188.

All that tells me the water pump is good too (I have a flowkooler sitting on a shelf for if that becomes an issue). The last thing I’m going to check is the return hose to the radiator and keep trying to burp it some more (it sat overnight ad a pretty good incline with the cap loose and I just went out and checked it and it looks like the level dropped a bit, which tells me there might have been some bubbles in there. I have zero coolant loss either. I did have some drips from the TB heater and even have one on the shelf at the ready for install (I was terrified it was a head gasket until I traced- and yes I’ve done the exhaust gas test to double check), but that has more or less self healed. I do wonder at times if there is a mild clog in the system…

 

So I’ve been letting it run for 20 minutes or so with the heater on after taking it off the incline. It won’t go over 194. If I rev it barely over 1k, it drops to 183 or 185 in 10 seconds or so.

I think it was bubbles.

Of note, I am still getting a scoshe of a water rush sound when I touch the throttle. Any ideas?

 

I'd say a more accurate idle temp would be to take at least a 15 minute highway drive and then pull off to a parking spot. Let it idle for 10-15 minutes and watch temps.

 

I just got back from a drive. It’s behaving perfectly again. It won’t get up to 201 at lights and when it got to 195 at a light it was at 188 at the other side of the intersection. Problem solved.

For Brandon, I say you have bubbles. Try what I did if you can and let it sit overnight.

Another method Tom from GBR told me (and only do this if you are comfortable doing it) is to pull the cap and plug up the overflow hose and actually blow in the expansion tank while cracking the bleed screw at the main junction. I’ve done that on all the other Discos and it worked perfectly. This is the first Disco I’ve had issues bleeding.

 

I just picked up hose to delete the throttle body heater (5/16" for future searchers, just run from the intake manifold nipple to the expansion tank) and will report back if this alleviates the gurgle. The TBH is the only spot I have a leak, so reasonable to assume it will.

 

Reporting back - I removed the TBH, tested again, and temps are holding solid between 190 and 194 now at idle. The leaking TBH was letting just enough air in the system to create an air bubble, which I guess was the cause. Glad to have my faith in new disco parts somewhat restored with the cause not being the recently-replaced fan.

 

I guess I should re-prioritize doing my TBH if this comes up again.

 

Why are you guys still messing with the factory thermostat system. Proven unreliable, difficult to bleed, and causes issues like this. Get an inline and you will never worry about any of this crap again.

 

My idle temps occasionally get to 212 in summer heat after a highway drive. Never really above 201 ever when moving at any speed. Typically 183-194. New fan clutch this past summer. Almost new coolant system. 180 inline kit.

 

I always a baseline of a machine until I get to know it. I definitely agree the in line solution is better, but again, wanted a baseline.

But I also have never had appreciable issues with the OEM design- unless I screwed something up, and since mine is not a daily, I can live with it. If in the future I end up in the system again, I’ll be doing an in line, but I suspect I’m good for a couple years or so.

I did drive it to work this morning and it went to 201 at a long light. Otherwise it wasn’t over 188 during the whole drive and the heat was on the whole way.