So I've done everything that I can think of to cure my overheating problem to no avail. I started with a coolant system clean and flush then replaced the thermostat, put an electric fan on it, replaced the water pump, the coolant temperature sensor, and put a new two row radiator in it. Everytime I've been sure to bleed the air out of the system. There is no oil in the coolant and no coolant in the oil. There are no bubbles in the radiator. I'm out of ideas here.

Axle

Could the gauge itself be bad? Though you'd either have to put in another gauge in another spot, or replace the whole cluster I guess.

Got a seperate gauge on the A pillar. It's getting up to over 260 and won't cool down. Even at idle.

Axle

Did you pressure wash the fins of the radiator to get out all the mud and bugs?

Sorry..just saw the two row install.. Try running it with no thermostat and see. I have purchased some bad NEW thermostats from time to time.

--Just some ideas--Turn on the heater with the selector to the extreme red-the temp guage should go down-IF NOT-your divert valves are DEFUNCT. Dril several 1/8 " holes in a NEW thermostat. If you have aftermarket bumper/lights/crossbars, you are probably restricting DIRECT air flow-FIX--good luck --JIMBO

Spend some time running a slow water stream through the AC condenser and radiator it self. Mud is a bitch, take you time. If you loosen the top two mounts off of the rad you can seperate it from the condenser and wash it out better.

He already installed a NEW upgraded radiator. Should be pretty clean.

ooops, missed that part.

OK, here's a shot in the dark. I worked on DesertHB's Xterra, and found the timing belt really loose. Could actully take it off without loosening anything! He was also overheating. We thought we were going to have to take the heads off, etc.

Anyway, we ended putting a new water pump on it, as the old one was questionable, some play and whatnot in the shaft. Then we installed a new belt, with the proper tension on it, and zoom(!) it not only ran better, but didn't get as hot any more. When we ran it up hills, a/c on, dogged it, et cetera, she got warmer, but never like she did before.

I'd wash out the a/c condensor, but double check the tension on the t-belt. A new one is cheap, and if does fix it, then we're on to something.

I put a new timing belt on it last fall along with a new water pump right before I deployed but didn't replace the tensioner. Really think that'd have something to do with it?

Axle

Nah, the tensione wouldn't have anything to do with that. I forgot you already did the belt! I think you even told me that to.

Will it actually get hot enough to spit out coolant?

No, that's the odd thing about it. It's reading up to 260* but I'm not getting any sort of coolant smell from it. The new thermostat not working is the only logical thing I can think of right now.

Axle

Not trying to be a jerk, but could it installed backwards. I haven't changed it on the X, but I know on some vehicles it can be accidently installed backwards and that would cause the problem. Just trying to think simple.

thinking out loud for a moment...

you mention that you've got a separate guage, how do you have it patched in? is it possible you have a bad sender?

it's odd that you'd be running THAT hot and not at least spit SOME coolant out the overflow...

i'd think that if the thermostat was stuck, the temperature wouldn't level off, it would just keep going up until it eventually "blew it's stack" and vomited up all the coolant...

I put a new temperature sending unit in and am using the new gauge in place of the factory one. I just unhooked the factory wire and put mine in place. This is temperary until I can get the CLICK I was going to get it when I ordered my gauges but since I was in Iraq at the time and couldn't check for myself I was unsure of what size to get. I asked for help here but never got an answer as to what size I needed. Gotta go back now in a few days so it looks like it's going to have to wait till I get back this winter to get finished. I got another new thermostat to try in the meantime. Hopefully I just had a bad "new" thermostat.

Axle

Ok, I put a new thermostat in it today and I'm STILL overheating. At this point I have absolutely no idea what to do about it. All I know is that I'm sick of working on it for the same problem.

Axle

So the new sending unit and the gauge are designed to work with each other, right?

Do you have a OBDII scanner that can show you the ECT sensor value?

Yeah, same values. It's reading way hot on the factory gauge and sticks around 260* on the new gauge.

Axle

Very weird. You're either not getting sufficient coolant flow through the radiator (i.e. stuck thermostat or poorly performing water pump) or you're not getting sufficient airflow through the radiator (i.e. electric fan doesn't pull enough CFM through)

Does it run super hot at idle? You mentioned you have an electric fan. What kind is it? How is it mounted? If it's not shrouded, it may not pull enough air through the radiator.

Try removing the thermostat to see if that helps.

Ok guys heres a poke at it. Have you, or had someone use a block tester on it? If not, do so, you may have a blown head gasket that is causing this. I have seen it with other makes. I know you stated you did not have the other symtoms like bubbles, but it does not matter. Still might be a blown head gasket. You may also presure test with a pump that screws onto your radiator where the cap fits. Pump it up to your cap pressure, watch the pressure for a drop, then as you run the motor see what goes on. The pressure should never go above the cap pressure rating. There is also an adapter to check your cap.

I hope this helps! Good luck.

Well I'll try the pressure testing when I get back home. Gotta go back to the desert for a few more months. I was just hoping to be able to fix it while I was home on some R&R.

Axle

be safe!!