Looked around and didn't see anything the same as what's been happening over the last couple weeks. 2006 LR3 4.4 with 125k

First noticed something wrong with the fan going full blast at most times over the last half dozen or so short local drives (I live in a small town and we take the outback for longer trips). Thought it was strange but hadn't sat down to troubleshoot it and the gauge was never more than the halfway point--it's usual position. But yesterday it full on overheated on a 15 minute drive: temp gauge up to the top, smell of hot engine, etc. It also seemed to lose power. I pulled over pretty quickly and let it cool down. Coolant full in the bottle but not blowing out and oil level at the mid-way point. There didn't seem to be any coolant in the oil or vice versa. Let it cool for 15 minutes and drove towards home when the gauge went to the top again in about a mile. Pulled it over and walked home. Drove it the last mile home quickly this morning stone cold (well, 75F).

Pulled codes with it in the driveway. P0217-00(68) "Engine coolant over-temperature condition" and nothing else. Not super helpful. Cleared that. Pulled out the t-stat and disassembled it, inspected it and put it back together. It's super clean with no issues with the rubber or sealing surfaces. Zero muck or dirt so if that's any indication of the cooling system, it's good. I started it and idled it for about 15 minutes with the reservoir cap off and the coolant temp seemed to level out at about 206 so I took it for a spin. About 10 minutes in, fans galore but still 206F, then I look down and the gauge is all the way up again but IID still says 206. I headed home and ended up with 253F coolant and 242 oil temps. Yikes. It was definitely bubbling coolant through the reservoir so I feel like I know the thermostat is working.

Battery and alternator replaced in the last year, alternator appears to be putting out 14v plus or minus but I wouldn't think this is electrical as there actually is overheating occurring. I replaced the reservoir maybe 6 months and 1500 miles ago with no issues. Any idea what could be causing this? TIA.

 

Hmmm.....only time I experienced this, I ended up replacing the thermostat and that was that.

 

Are you down any coolant? Do you have any leaks? Off the topic of my head the list of overheating causes I would run down are:

1. water pump failure (would cause overheat with full coolant);
2. head gasket failure (would pressurize the coolant causing a leak);
3. leak resulting in low coolant;
4. radiator efficiency / clog type issue (maybe, seems a stretch?); and
5. thermostat failure (failing closed).

There may be more ideas that others might have.

If you have not lost any coolant, I would look first at items 1 and 5. I know you said you cleaned the thermostat, but you might want to test it in boiling water outside of the car. If the t-stat is operational, then I would ask whether there are any whines coming from the water pump. Changing the water pumps on these cars is not hard, and if you have not had it changed at that mileage, you may wan to consider changing it. With a new gasket they are under $40 on ebay.

If you are down on coolant, I would look at #3 first (dye + UV light is really helpful at finding leaks).

I purchased my LR3 with an overheating issue at 199,000 miles. In my case there was a clear leak as the system would not hold pressure and once the t-stat opened the coolant would billow out in a white cloud. The plastic water crossover pipe had fractured in my case.

Good luck with it. While it could be various items, the issue that to me fits your symptoms the most -- assuming you're not down on fluid -- is water pump or t-stat failure.

 

Thanks to you both. More google research later, I wonder if I'm not dealing with air in the system. I may try to bleed it before I do anything else. There's no new noises and I'm not actually DOWN coolant and in fact if anything, there's more in there than I remember. Definitely holding pressure as well. It's not frothy or oily in any way but I'm super wary of a HG failure. So far though I don't see any evidence pointing to it.

I guess the good news is that if the bleeding doesn't work, then at least the t-stat and pump are under $100 combined. Are the $40 WP's really decent?

 

You're welcome. I'd find it a little strange to have air in the system randomly. I think testing the thermostat in boiling water is a great idea. I'd bet a beer that's the culprit, based on the info you told us. I went through all of these issues just over a year ago...water pump leaking, thermostat failed, had to replace the coolant reservoir because the nipple on top where the hose attaches broke! I did have to burp it after refilling the coolant, but that was clear. The over-temp issues were due to the t-stat. Also, as long as a person is fairly on top of it and pulls over quickly, it's not that easy to blow a head gasket on this engine.

In my case, my wife had taken the '06 out to the store, in the snow on one of those uncommon snow weeks in the Seattle area, when the t-stat failed. It got hot and was in limp home mode. She freaked out and called me. I drove to meet her in our '05...put her in that to drive home, and I nursed the '06 back. I wasn't sure how long she had driven it hot and was pretty concerned about the head gasket....it was fine.

 

I'm with houm_wa, I have trouble seeing how air would get into the system absent some other failure (e.g., a leak). By the way, there's a youtube by Doug from Atlantic British that's excellent on how to burp the LR3's coolant system.

 

Add me to the list betting on a failed thermostat

 

I was more worried about a head gasket being the cause of the overheating rather than a downstream effect. Now I'm a little more worried because....

I removed the thermostat and reinstalled the housing. This should (tho correct me if I'm wrong) rule out the thermostat being stuck closed. Temps rose to 240F and hovered there. Seemed to bump up a bit if I drove and drop back to that if I idled. Idle was high, about 1150. Fan going crazy and a bit of a rough idle. This is why I'm worried about a HG at the moment. I'm not noticing white smoke or any dilution of the coolant though. At some point I owned a leakdown tester and I may need to break that out.

I did test the thermostat saucer in a pot of boiling water but it didn't have the housing so I think it's not a valid test. I didn't realize it's just changing the length of the stud coming out of it and since it wasn't in the spring loaded enclosure, it couldn't do it's thing. But again, I'd think with the thermostat entirely removed from the vehicle, I'd expect it to be running as cool as it's capable of.

Are there any tests I can do to rule the water pump in or out? Thanks all for the input, I appreciate it.

 

I'd put in a new t stat anyways, it's a cheap enough part to just do it.

Did you get the air out of the system after removing the t stat and doing your latest test? Opening the housing will introduce air. Also even doing the full air bleed steps with the throttle body T and overflow bleeder you can still have air trapped. What I've had to do is bleed the air out then if it starts overheating on the first drive, pull over and loosen the coolant reservoir cap. This will burp remaining air.

for additional tests if the above checks out, I'd do a leak down test. If it's still overheating and that passes then probably the water pump.

 

The local o’reilly’s surprisingly had a t-stat in stock so I picked it up. I re-assembled with the new parts and dropped it in boiling water. Did not really open much, which surprised me. But I went ahead and installed it. This time I also pre-filled the hose downstream of the t-stat and then for good measure injected more coolant mix into the throttle body coolant bleed valve. Between those two, there was maybe 2/3 of a gallon of air displaced which I’d think is kind of a big deal. I’ve been out on a couple drives and have burped and refilled it (very little added) once each and it’s sticking around 210F now. That’s progress! Can anyone let me know what’s a “normal” temp in 80 degree weather?