Hilux 4x4 Forum

Hi Guys

I am a new owner of a 2006 Hilux 4l V6 Auto 4x4 DC with 229000km. I have noticed that the temp gauge goes up under load on the highway. If I put the cruise control on at 130km/h and I am driving into the wind and going up hills the gauge will go up 3/4 or if I put my foot flat going up hill the temp gauge will go up slightly above normal. It takes a long while for the temp gauge to normalize. In town I have not noticed the temp going up at all. I have bled the cooling system as the first time I noticed the temp gauge going up was after using the heater, and I thought there might be an air bubble. The cooling system has not lost any coolant and as far as I can see and the system pressure seems to be ok. My question is does the temp gauge verify this much as the book suggests or is there a problem?

Regards Cookie Monster

At that km you should replace the waterpump and while you are at it the thermostat
And fil it up with the toyota antifreeze. The waterpump a good quality after market pump and the thermostat, antifreeze from toyota

Thanks Mossie do you think that might be the issue?

There are a fair number of possibilities here, but on the face of it an airlock seems to be an unlikely cause.

I have come across motors that have that problem and need to be bled but such motors are generally from decades past and usually have a bleeder screw / valve. In such cases the design of the water jacket in the head has less than optimal flow through an area that has high points where air can remain trapped. However, if that were the case, such pockets would allow the formation of steam, resulting in expansion and forcing coolant out at the radiator cap.

Don't open the cap if the motor is hot, but if you can see coolant flowing across the top of the radiator through the cap hole, then it's probably not the pump or thermostat although a weakness in either or both could be contributing factors. The fact that this happens when the motor is under load, more often than not indicates a radiator problem. Could be that it has partial blockage and flow is restricted, or the fins have corroded and are no longer able to transfer the heat away quick enough. With an older vehicle this is a very likely cause as is a poorly functioning visco fan. Check them both.

Having mentioned the problem started with using the heater, it could be co-incidental, but you could have a faulty valve. I don't know what yours looks like but if it has two pipes (in and out) then it's not the issue. If it has three pipes (in, out and bypass) it's possible that the valve has not fully opened the bypass (heater off position) and flow is restricted. When the problem occurs again, put the heater on (you don't need to put on the fan as well) - if the temp gauge drops, this should tell you that the 3-way valve is faulty. I hope that's the problem and that's all it is.

Good luck.

Thanks guys I dropped my baby of at Algoa Toyota this morning hopefully will get feedback today or tomorrow. I just hope it's not the headgasket! They will be doing the 230000km service and attending to the brake shudder as well.

Maybe time to pull iut the radiator?

A mate almost lost his Pajero'a engine due to a partially blocked radiator.

As I type this, I am busy cleaning up the radiator and intercooler of our Freelander - 220 000km and you will not believe all the crap that was blocking the radiator. I guess around 30-40% was blocked.

The last few weeks I smelt the car was running hotter than normal. I believe I caught it in time.

At this stage I am drawing to a conclusion that vehicles aproaching 200 000km, the radiator should be pulled and cleaned.

My 0.0000000000000142 bitcoin worth.

Hi Guys

Just an update on my overheating Hilux. The fault was traced to a seed and mud build up between the radiator and the condenser. The Hilux had it 230 000km service as well as the front disc and pad replacement and the a radiator replacement at Algoa Toyota. I have over 200km and she is running 100%.

Next Question has anyone thought of adding a additional electric fan to help with cooling?

Good to hear that you got it sorted and the cause was a simple one. Make up a seed net with some shade-cloth and keep it behind your rear seat so that you have one if needed in the veld. You can see now how useful they can be. It starts with seeds, moths and the like and then dust / mud packs up and restricts air-flow.

The second fan has been done before and in fact I did it to my first SFA Hilux. I mounted a Merc W123 series electric fan in front of the air-con radiator (condenser), but I wired it up to come on when the air-con was being used. That way I didn't have to install a termo-switch to control it and it made a big difference to the air-con. Connecting it to run continuously is unnecessary and creates unwanted strain on the alternator. The alternative is to fit a switch in the cab and select when you need to use it.

Mud Dog wrote: ↑Wed Jan 03, 2018 12:24 am ....................but I wired it up to come on when the air-con was being used. That way I didn't have to install a termo-switch to control it and it made a big difference to the air-con. ..........................

The only problem with that is that on a Toyota the ECU disables the A/C system when it detects excessive water temperature and then the extra fan is useless at the point you really need it most. So I would have the option of an override switch on top of the A/C trigger. BTW never mind having an extra fan for the engine, it does wonders for having cold air in slow traffic or being stationary

The ECU bit I didn't know about. Mine was done on an old SFA - no ECU, but then yes, an over-ride might well be the way to go.

Knuppel wrote: ↑Tue Jan 09, 2018 10:49 am

Mud Dog wrote: ↑Wed Jan 03, 2018 12:24 am ....................but I wired it up to come on when the air-con was being used. That way I didn't have to install a termo-switch to control it and it made a big difference to the air-con. ..........................

The only problem with that is that on a Toyota the ECU disables the A/C system when it detects excessive water temperature and then the extra fan is useless at the point you really need it most. So I would have the option of an override switch on top of the A/C trigger. BTW never mind having an extra fan for the engine, it does wonders for having cold air in slow traffic or being stationary

so is that why my aircon stops working when its super hot and you need it the most ?

That would most likely be the case, but it's a better option than overheating the motor. Despite this, it might still be a good idea to fit a pancake fan in front of the radiators and couple it up so that it comes on with the A/C. Also regularly check that the radiator fins aren't blocked with insects / debris so that airflow remains optimal and that the visco fan is in good order. The more efficient the cooling system, the less chance of the ICU isolating the A/C.

Just as a point of interest is that in December i was towing a trailer loaded with the Prado in 44 degree heat with the aircon on and it never switched it of on the ecu, but the Prado does have the additional cooler fan in the front of the radiator which helped a lot in my view. So maybe wiring in a fan will produce some great results.


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