Hilux 4x4 Forum

Morning all. I have just bought a 2009 kz-te Prado with 254000km on clock . It's in immaculate condition. Never been off road , as there is not one dent on bash plate..
It's just had injectors replaced and a water pump.
It was done in December.
Question.. drove her home , parked in garage. Next morning opened coolant bottle cap and there was a fair bit of pressure. Is that normal ?

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To my mind, no. But it does probably mean that there are no leaks in your cooling system, so that could be positive.

Is there a cap on the radiator itself as well? Could be that it's not allowing the coolant to return to the radiator from the bottle when cooling down and contraction takes place. I would replace that cap if there is one - inexpensive item. If you're not loosing coolant and there's no indication of overheating then I don't think there's anything to really worry about.

I hope that it is not the case here but pressure in the system when cold could indicate a blown head gasket. Just check carefully if it is using coolant.

Thanks mud dog and mars.
There isn't a radiator cap that I can see. It has plastic covers over the top. I presume there isn't one.
I am meant to be going on holiday this wknd for 10 days . Will cover over 1500km.
I haven't driven it again. Since I got it early this wknd.
Will a pressure test determine whether or not I have a cracked head or blown gasket ?

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A pressure test should show a leak. They can also test for exhaust gases in the water. Do you smell exhaust gases when smelling the coolant in the bottle?

A dead giveaway is losing coolant and a tendency to run hot.

The 120 Series Prado KZTE is a pressurised cooling system with the cap on the expansion tank and not on the radiator. So there should be some pressure in the system when cold also, however it should not be so much that it pops the cap off when opening it cold.

The system is basically "sealed" as the expansion tank is part of the pressure system and only when to much pressure / heat will it blow coolant out the small overflow pipe.

If there is no indication of overheating when driving normal, I will not be to worried, as those engines are strong, and if there is a problem should manifest quickly.

Funny enough, the 120 KZTE engine has reported much lower failure rate than the 90 series prado's and the Hilux KZTE's. Even in Australia not a lot of problems with these. Just lazy but great allround.

If you look in the picture you will see the cap sitting behind the radiator on the bottle and these type of pressurized cooling systems are used mainly in engines that are turbo charged and high temperatures to absorb. The D4D motors are also using similar design.

Thanks Johan. That is valuable feedback. I also think it's stronger than the kz-te bakkie. In my opinion , purely because it has an intercooler. Which I'm looking at putting on my kz-te bakkie. I just took it for a 5km drive through some small hills on the farm, mostly in 1st gear. Temp didn't really get to the just below half mark. Sat at just over a third.
If I get a chance , i will take it to Silverton anyway. It just means a 2 hour drive. Good thing I love driving

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Hi Malcolm yes the Prado 120 has more torque than the KZTE. 5km will not warm up the motor enough on farm speed driving so about 1/3 does sound right. Best is to take it to the guys and have the gas test done and take it from there, but I hope and doubt that yours have big issues. Also if the cap needs to be replaced, don't buy anything except the correct cap from Toyota. They seldom give trouble but best is to be safe and get the correct part.

For the Hilux the best is to source a front mount intercooler, and fit it in the front.

A lot of small changes has been made on the KZTE motor that is in your Prado compared to the first one's in the HIlux.

Thanks Johan. I will order a cap.
Yes I also thought that as my kz-te is 2001 and Prado 2009.it looks like a better motor from the outside.visually looks better put together .

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JohanM wrote: ↑Wed Jan 30, 2019 1:06 pm The 120 Series Prado KZTE is a pressurised cooling system with the cap on the expansion tank and not on the radiator. ......

The system is basically "sealed" as the expansion tank is part of the pressure system and only when to much pressure / heat will it blow coolant out the small overflow pipe.

That's why I asked if there was a cap on the radiator. To my mind, I don't think you have a problem .... if there was a cracked head, blown gasket or any leak then the pressure would dissipate through such. Additionally, unlike Johan, I think that a five km drive in low gear should have reached operating temp quite early on, especially if it wasn't in the cool air of early morning / late afternoon .... at low speeds there is no 'ram' airflow, only from the fan. I think if there was a problem it would have shown up. Just keep an eye on the coolant level in the expansion bottle.

Thanks all for your input . My mind is at ease some what. But I will most definitely keep an eye on it. Thanks again for your time

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If you replace the cap you can just as well replace the thermostat as well. Always good to replace it as it is a very important part of your cooling system.

Check the colour of the coolant. If it is a charcoal/greyish or black, the cylinderhead is cracked.

Fill up the expansion tank with water to the neck of the tank start the engine with revs on 1000 rpm keep eye on water in tank, level will increase and overflow for a while no problem but if there is bubbles coming out let it tested with gas analyser .

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Thanks for all the feedback. I have now been driving it for a bit. There is still a reasonable amount pressure in the bottle. But she seems to be using a bit of water. On start up she still smokes white smoke for a couple seconds. Still working out where the water is going as it is still pressurised. Oil is still good and clean.
What should I be getting tested to find out ?

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Swing past Silverton and ask them to do a carbon monoxide test on the coolant. That'll tell you if you have even a small leak between the combustion chamber and water jacket. Since your oil is still clear, that's where it's likely to be if there is any leakage. Other possibilities are areas of the coolant reticulation that you might not see easily, like the heater radiator / pipes behind the dash or any external pipes that are not in plain sight.

Thanks mud dog. I'll get that done when I manage to get town

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I hate to be the prophet of doom but it is starting to sound more and more like a blown/cracked cylinder head. I certainly hope not. The cylinder is under very high pressure on the compression stroke so it is not strange to have pre/combustion gases forced into the coolant. This will usually happen long before the channels between the water and oil are compromised.

Thanks Mars .
What's the process of getting it fixed ? Is it a massive expense ?

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Hi Malcolm

There are two issues. If the head gasket blew because of overheating (causing the head gasket to warp) then it would require the removal of the cylinder head and having it skimmed and to replace the head gasket. The parts are not as expensive as the labour. Quite a bit of work to get the cylinder head off.

If the head cracked then you would be best advised to replace the head with an AMC unit. I am not sure exactly what they cost now but it is quite expensive. At least you won't have any issues with the cylinder head again and it is universally accepted that it is money well spent.

Before you start panicking. Have you replaced the thermostat? A thermostat that does not open properly anymore also causes the system to run hotter thus causing higher pressures. The coolant will find a place to escape if the pressure in the system is higher than spec. You will need to fit a new thermostat in any event. They are cheap enough.

Is the radiator clean (inside and outside)? Even if you are going to replace the head gasket or cylinder head you would be well advised to have the radiator cleaned and flushed.

Also check the visco fan to see if it "tightens up" when hot.

Usually a car running hot is a combination of factors due to wear/age that contribute. The only exception is the known issue of the KZTE head cracking. (Although I am not sure about the KZTE engine used in the Prado and if it is any different.)

Thanks Mars.
I have t yet replaced anything , I haven't had a chance. I have just returned from a 1700km trip with a full car and trailer.
She used a bit of water but nothing major. Half a cup every 400km or so.
I still need to get to town and change thermostat.
I just had a quick inspection of engine bay. There seems to be a bit of seapage of oil where the intercooler pipe joins the common rail. I haven't been able to get under her for a full inspection.
Awesome four wheel drive though. That centre difflock is something special.

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Hi all . Narrowed it down to cracked head and blown head gasket. It was all very early signs.
Thanks again for all the info and help

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Eish! Replace with AMC head and if no gasket supplied, get a decent quality one, maybe the one supplied by Toyota.

Sorry to hear that. If you do it properly you will have many 100s of thousands of trouble and worry free kilometres.

I drove my Kz for 14 000km since discovering some water usage until head replacement, just topped it every morning and never had any issues.

Thanks gents. Unfortunately I didn't put an AMC head. I really would of liked to , but the extra 4k was just too much for what I could afford. I figured that with an intercooler and the amount I will be using the car , it should be ok. It is my private car and my wife has her own vehicle. I'll only do about 10000km a year , the rest of the year I'll be in a work vehicle. Which is also my kz-te , 2001 4x4 double cab.
Have a huge amount of play in the front diff that I need to attend to, it's the right front side shaft where it goes into diff. Very nervous to open it and find out what's lurking in there, in the meantime I'll be running around in 22R SFA.
. Fingers crossed..

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I bough a R4000 head from Heads for Africa and it worked well - an AMC is nice but was double the price.