Navara runs hot uphill

[user 50884]

I’ve got a navara automatic with the yd25 engine that seems to run a bit hot uphill. But only on days when it’s 35-40 degrees outside. It does not happen at night time.. the most I managed to get the temp to was 116 which is just under the red on the gauge.

I’ve replaced radiator, thermostat, coolant flush, checked hoses and for leaks (I do not loose coolant). Checked clutch fan and electric fan.

The previous owner seems to have replaced the cylinder head, water pump and exhaust manifold.

Would a blocked cat or dpf be likely?

 

[Old.Tony]

Shouldn't be affected by the cat or DPF. Forget the electric fan.

Things I'd check:

* Inspect the fan blades. Cracked roots will allow the blade to twist, reducing its power. This could also (easily) cause the fan to eat out the back of the radiator, so it's first on my list.

* Driving lights. I had a pair of rectangular IPF 800 driving lights plus a light bar, and if I mounted the light bar below the top of the bullbar, the engine got hotter more quickly. I moved the light bar above the bullbar (temporarily) and the problem went away. I now have just the light bar, the two IPF spotties are gone, and I have no problem.

* Proper operation of the viscous hub. I know you checked it, but make absolutely sure that when the engine temp is at 91C or higher, and the engine is turned off, the fan should stop at the same time as the motor. If it doesn't, that's your culprit right there.

* Park the car nose-up (about 10-15 degrees is good) and idle the engine for a minute before shutting it down. Let the engine cool enough to open the radiator - check for coolant. Air sometimes gets trapped inside the coolant path and stops the system from functioning as well.

* Dragging brakes. Drive the car around (level ground is preferred for this) then stop and check the disc and drum temps (more likely the drums). If they feel warmer than you'd expect, it might be time to check them out. We've had guys report theirs were full of debris in the past (mud, usually).

That's a start anyway, the most common things are there.

 

[Chapster]

Hi Perrka,

As he does Tony has covered the main bases.

While waiting to get to the bottom of it, I reckon it might be wise to run the Torque App (or similar) with an alarm set once coolant temp reaches a certain level. I have mine set to I think 100°c, though others may set theirs higher. I am pretty gun shy though after having already replaced my motor after a seemingly innocuous overheating episode.

And that's the key thing here: it's somewhat accepted wisdom the YD25 is not a fan of heat and, to make matters worse, the in-cabin gauge is notoriously unreliable. You could easily cook your donk before the temp gauge tells you there's a problem.

Running the app would be a good, but not perfect, safety net while you resolve your overheating issue.

If you lose coolant, an app alarm (like the temp gauge) has its limitations and you may want to consider installing a product like Engine Guard or Engine Watchdog, both of which take their reading not from the coolant sensor (which can run dry) but the head itself.

Apologies in advance if I am telling you how to suck eggs. Just thought I'd mention it.

Good luck.

 

[Old.Tony]

^ Torque is a brilliant app. My alarm is set to 105C, which is the temperature that the ECU brings on the electric fan to assist in cooling. That's not a danger point - you can safely let it go to 110C, but I prefer to be cautious in case there's some lag in the sensor/updates or a minor voltage fluctuation causing a slightly lower reading.

I usually don't let it get to 105C anyway - up a steep hill (Thunderbolts Way is an often-travelled road for me) I let it hit 102 and I'm backing down the gears, so that it peaks at 103.