So after replacing to brand new genuine Land Rover parts on my coolant system minus the radiator as that is only 3 years old, the damn thing still overheats. I didn't see it go to the red as I get scared and shut off the vehicle before it does but right now in Texas it's colder than a witch's titi, so I thought it would be because there's frozen water or something. I put in the pink prestone for land rover coolant with a gallon of distilled water because I lost coolant bleeding and some that had spilled out of the reservoir. Anyways so I turn it on and it took maybe 5-10 mins to warm up then the temperature would rise up to the line. Aside from looking at the temperature gauge on the dash, I also have the ultra gauge plugged into the OBD2 port. Damn thing rises all the way to 244-251° F at idle very odd, another odd thing I discovered is that when press the gas peddle to get to go up to 2000+ rpm the temperature drops down to 235.4° F and it stays there. I release the gas peddle and once again it rises then I repeat the first step and drops back down. I said screw it and took for a spin, under 2000 rpm, I'd say around 1700-1900 rpm the temperature rises to 244-251° F. I give it more gas to go up to 2000+ rpm and the temperature falls down to 239° F. I'm like so tired of messing with the damn engine, I'm just gonna bite the bullet and do an LM4 chevy swap. I mean the whole kit costs $5400+, that's close to if not cheaper than a remanufactured 4.0 L engine. I had wanted to keep it original or whatever but like screw it, idc. Oh and before anyone starts asking questions about what my question is, read what I just described. There's no question, but here's one if you really want one. I have all that going on, what do you guys think it is. I'll reiterate and add some additional information about what I've done so far. The coolant system has been bled properly.
With the engine cold
1.I open the reservoir cap
2. remove the bleeder screw
3.lift the reservoir tank
4. fill the tank and watch as a steady flow of coolant flows out
5. put the screw back on.
The head gaskets were replaced back in 2017, I bypassed the heater core hoses by attaching a U hose. I'm using an Ultra gauge.​​​ All coolant parts are new besides the radiator, top hose and the tiny hoses that go to the tank and radiator. That's it, unless I'm missing something. Oh the fan clutch is not genuine land rover, I actually got it from AutoZone.

 

Have u used an IR temp gun on the hoses to verify temps? Temp sensors can go bad, does it blow coolant out the expansion tank? With temps in that range "if" it's accurate under the hood would sound like a pressure cooker. Is the top hose rock hard? If so you're probably got exhaust gases getting into the cooling system. You can rent or buy the tool & fluid to check for that, but if it's that bad you'd likely smell fuel/exhaust gases in the coolant reservoir.

Also "if" those temps are once again accurate you've got yourself a set of warped heads at least.

Fan Clutch from Auto Zone is a good unit I use them myself with no issues.

 

No, but I'll buy one to verify. I actually changed the coolant sensor as well, it's a brand new genuine Land Rover part. Normally I do see coolant leaking out but it wasn't the case this time. I didn't completely fill up the tank, but it's sitting about half way. I don't hear anything, but then again it's not loud enough to for me to investigate, and before the hoses actually got really hard like they would balloon. I checked them and they weren't as bloated like last time. I was actually thinking of performing that test next, well if the heads are actually warped then the mechanic shop that did my head gaskets did a horrendous job then.

 

If the temps got up to the temps you mentioned = that's when they warped no doubt.

 

QUOTEAh well then I guess I'll do the head gaskets myself, shouldn't be to hard. Thank you for responding and giving me some insight.

 

Your thermostat s defective, and most of your coolant is bypassing the radiator. When you rev the engine the flow increases enough that some is going through the radiator. I recommend the inline thermostat mod as a first step, then you can figure out if the hg are blown.

 

Head gaskets are pretty easy.

 

Crap on a cracker, the thermostat is brand new too. It's the genuine land rover 180° F black thermostat. I'm not sure what the inline thermostat mod is, is that where I drill thru the thermostat itself? Yeah I rather avoid the HG if possible right now.

 

Yeah Atlantic British has a break down video which the process itself is pretty straight forward.

 

Slap the thermostat in a boiling pot of water n watch it. If it opens = not stuck. If it doesn't move = stuck shut it's as simple as that. Process of elimination.