120 series prado overheating issues

[markkab Lurker Find all posts View Profile Close markkab]

Hi all,
My name is mark just wondering if any one has any ideas or has seen this issue. I have a 1kz motor and the temp guage was going up when towing at 100kmh then when I back off the temp gauge instantly goes back to normal.it did it again today but this time I was not towing. Ive checked the basics like coolant level which it hasnt used a drop in 6 years no leaks radiator seems to have air flow. And fan seems to be turning.im not sure where the thermostat is on it to check it for restriction. Any advice would be appreciated.

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

Cracked heads are not unheard of with the 1kz.

Other than that, thermostat, radiator blocked or fan clutch not working are the first things I would look at.

Cheers Andrew

[Bushbasher Out of control poster! Find all posts View Profile Close Bushbasher]

You weren't pushing against the wind in that 45 degree heat the other day were you?

[ScoticusMaximus Member Find all posts View Profile Close ScoticusMaximus]

mine was getting a bit warm when the water pump was on the way out

[Rainman Advanced Member Find all posts View Profile Close Rainman]

Sounds like the the radiator may be blocked, particularly if it hasn't been looked at in 6 years.

[johna Member Find all posts View Profile Close johna]

Hi all,
My name is mark just wondering if any one has any ideas or has seen this issue. I have a 1kz motor and the temp guage was going up when towing at 100kmh then when I back off the temp gauge instantly goes back to normal.it did it again today but this time I was not towing. Ive checked the basics like coolant level which it hasnt used a drop in 6 years no leaks radiator seems to have air flow. And fan seems to be turning.im not sure where the thermostat is on it to check it for restriction. Any advice would be appreciated.

When you say temp goes up, by how much ? Have towed 2 1/2 ton with mine in air temps in mid to high 40's and temp only rises about 3 to 4 needle widths and is nothing to worry about. Have done 212,000 klms so far since 2003.

[markkab Lurker Find all posts View Profile Close markkab]

Thanks all flushed radiator seems to have fixed the problem..... guess I should have done that earlier.

[markkab Lurker Find all posts View Profile Close markkab]

Yeah it was going up to 3/4 have flushed radiator seems to have fixed the problem

[brissy Member Find all posts View Profile Close brissy]

Cracked heads are not unheard of with the 1kz.

Other than that, thermostat, radiator blocked or fan clutch not working are the first things I would look at.

Cheers Andrew

^^ and install a quality temperature gauge and check/replace radiator cap it may not be holding correct pressure

[ScoticusMaximus Member Find all posts View Profile Close ScoticusMaximus]

^^ and install a quality temperature gauge and check/replace radiator cap it may not be holding correct pressure

Im a big fan of extra gauges or madman/scanguage, something to monitor real temps, not just the dial, it only starts moving when its really hot

[404pug Avid PP Poster! Find all posts View Profile Close 404pug]

Also, my mechanic tells me that he has replaced quite a few Prado radiators at about the 6 year mark with corrosion att he bottom on the OUTSIDE . ie the aluminium starts to break up. This could mean less efficient cooling. About $250 aftermarket [ $700 ish genuine].

[SimonW Junior Member Find all posts View Profile Close SimonW]

My 1kz radiator failed in year 10

[Bushbasher Out of control poster! Find all posts View Profile Close Bushbasher]

1800km through 47 - 49 degree heat yesterday and scan-guage reading 94. Think my cooling system is working fine.