I've read through many overheating threads but couldn't find an answer so started a new one. The XG ute has had a new radiator and a new water pump fitted, but the coolant temp/overheating light still comes on when the needle hits the 'N' of NORMAL (gauge is same as EA-ED). Is this the normal point for the light to come on? It's been happening for just over 2 months now, prior to that it was fine, needle never even got to the N I don't think. And even after a new radiator and pump fitted last week, it has made no difference.

Things done so far in order:

Radiator flushed, cleaner added, re-flushed and 50/50 mix added.
New thermostat (opens about 92°) fitted, made it worse, light came on after a 1-2km of normal driving.
Fitted old thermostat (opens about 84°) back and light comes on after 10-15km of normal driving.
New radiator fitted. No change to outcome.
New radiator cap (20psi?) fitted. No change.
New water pump fitted. Nothing changed.

In my time of owning the ute (4yrs+), I have never seen the gauge hit the 'N', or the light come on untill about 2 months ago. Also the coolant in the overflow tank rises up when the rev's rise, then settles back when at idle. This isn't normal is it? Never really took notice of it when it was running fine. Is it normal for the light to come on when the needle hits the "N'? Why with the standard thermostat (92°) does it heat up/overheat so quickly?

Head gasket is most probably blown. Go get a combustion leak test done.

Does it have thermo fans? I've seen cars overheat pretty quickly when the thermo fans are eithier not working or plugged in backwards. Other than that, is the clutch fan operating correctly? do you have any water leaks? is there any milky crap in the oil or water? is it running on 6 cylinders? Is the ignition timing correct?

I'd be checking some of that stuff next.

Gab

Thanks BEAR80, but the head gasket is fine. Leak test was done, and all's good. Head was replaced 8 months ago, AU gasket used. Coolant level was always good, no leaks.

Thanks Gab, no thermo fans. Clutch fan is working 100% fine. No leaks. No milky crap in the oil or water. Running on 6 cylinders perfect and Ignition timing is correct.

Anyone know at what tempreture the light switches on? I might hook up my multimeter's temp sensor into the outlet hose and see at what tempreture the light switches on. After all we've done, I hope it's not something stupid like a faulty dash temp sensor, that would be how embarrassment! But I'm not willing to keep driving for long distances just incase it really is overheating.

Question for the EA-ED and XG owners, where does the temp needle normally sit on the temp gauge? Below the 'N' or above?

replace the coolant temp sensor

+1

condensor clean?

When was the last time you cleaned the condensor... Over a slow period the normal operating temp on my car will creep up... And every so often I'll blow the condensor out... You would not believe the amount of insects and dust that gets jammed in them... New radiator ensures that isn't blocked, but if the air cannot flow through the condensor then it can't get to the radiator to cool the water... Cleaning mine makes a world of difference...

To clean the condensor we innovated a tool to be able to do it with the radiator in the car... But basically you just used compressed air and blow everything back out of the condensor toward the bumper... Out the way it go wedged in... Without the tool you'll need to take the radiator out or get enough clearance to get the air nozzle down between the radiator and condensor to clean the whole lot out...

Make sure nothing important is in front of your car... It will become covered in insects otherwise...

My car (ED with EL cluster and computer) runs just above the bottom normal line on the gauge... I also run the tridon high flow thermostat suited to that model...

The water level goes up and down as you rev the car that tends to imply you have water circulation and nothing is blocked water wise... Ever has the welch plugs out and checked the bottom of the block to ensure it isn't full of crap? Nothing funny that may have happened when you changed the head gasket?

Failing to ensure you have unrestricted water flow and unrestricted air flow through the front of the car (that is oil coolers, condensor and radiator as the radiator is last to get the air) then i'd be moving on to looking at the electronics... Two parts to the system... Sender and gauge...

From the Ford manual for EA-ED items are:

->Loss of coolant
->Belt tension incorrect
->Radiator fins obstructed
->Thermostat stuck closed
->Cooling system passages blocked by rust, scale or other foreign matter
->Water pump inoperative
->Fan drive clutch defective
->Ignition initial timing incorrect

The only mention the sender in the "my car runs cold" section...

Your ute has the 6 gauges? Later production (EB onward equivalent)?

if you measure the temp sender resistance to earth you should get the following:

Cold marker -> 221ohms
R to M region -> 70ohms
Hot marker -> 39ohms

But N is closer to cold by the looks of it so the lamp shouldn't come on... Manual doesn't spec the resistance for the lamp to come on... Seems odd though... The more I think about it the more it seems electronic...

Cheers,
Tim

Next on the list. Where does the temp needle sit on your EB and EA mate?
Yep, cleaned it before and after radiator was out.
Thanks Tim, all of the above is done, or checked out ok. Put both the new and old thermostats into a pot with my multimeters temp sensor and bought them to the boil, both open fine and that's how I got the opening degrees in my first post.

Coolant system has been pressure tested and was all good. So the coolant rising and falling in the overflow tank with the rev's is normal?? I thought it wasn't. It goes from being at MIN, to right upto the cap from idle to 3500 revs. So the coolant temp coming out of the engine should be about 85° since that's about where it opened when I put it on the oven, and remain at that temp and to about 95° maximum yeah??

sits on the line between the blue bit for dead cold the normal when driving. so pretty low. but i got thermos. so in traffic it gets to between the R and M then thermos cut in and it drops down to the L

So I bought a new temp sensor. I inseted the multimeter temp sensor to the top hose, and the light comes on at 84° with old temp sensor (just as the thermostat is opening as tested prior). The tempreture then drops down to about 77° and slowly climbs up. This is at idle. Installed the new temp sensor for the light/gauge and the multimeter once more. Again the light comes on at 84° and same situation as above!! New sensor didn't make any difference! Why on earth would the light come on at 84°?? That's not even close to overheating is it?? I would have thought 100°+ would be closer to a overheating issue. Even with a 50/50 mix coolant.

The local auto coolong/radiator specialist has no clue as to what is going on. I have no idea what to do next. I could choose to ignore the problem, but as I said, in the 4+ years I've had this ute the temp light never came on, and needle never got to the N. So something is not right, and I don't want to risk overheating and possibly doing more damage. HELP!

So you didn't multimeter it like I said? Would've saved you having to buy a sensor... Just needed to check it's resistance...

Next I would try swapping out the instrument cluster and see if that has any benefit... See if you can just borrow one to try though... Must be costing you a fortune to just suck it and see...

Or... Try inserting the values of resistance I have mentioned, but your gauge is working fine isn't it? Just the light is acting up? Try swapping a whole instrument cluster just for the sake of trying something...

Cheers,
Tim

i've got the perfect idea. if it isn't overheating. and the temp gauge works okay. pull the globe out of the light.

Is it doing this on the highway or at low revs?
A common overlooked item is the bottom hose internal spring disintegrates and the hose sucks in as you drive restricting flow and causing overheating issues.
Also ditch the thermostat and get a Dayco DT13C or Tridon TT233-170 , both open around the 70 degree mark and will stay open.
Also is it really hot??? get a cooking thermometer and test the watr temp in the reservoir in context to your guage, it may not be hot at all and only a dodgy sender. Mine barely runs on the guage on its best day with AC on