1KZ Cracked Head

[Farmer Lurker Find all posts View Profile Close Farmer]

Hi all,
We have a 2005 120 1kz with about 250,000 only had it 12 months and it over heated the other day to just below red line. On inspection the coolant was low, overflow tank empty:???: I've had it pressure tested and its holding no probs. tk test tomorrow...what ever that is. It used bout half a liter of water driving the 30 ks to the mechanics but no obvious signs of leaks and bubbles in the radiator.

Question is ...is there any other ways of diagnosing the problem without actually removing the head.

Mechanic said there was a slight water stain under the water pump but given the quantity of water I'm losing we doubt it the cause.


Any thoughts.

[scottkz Senior Member Find all posts View Profile Close scottkz]

Not a good idea to keep on driving it..... Few hundred ok but more the water will start piting the Pistons

[Farmer Lurker Find all posts View Profile Close Farmer]

Thanks Scott, wasn't aware

[Farmer Lurker Find all posts View Profile Close Farmer]

It was the radiator cap! Guess I'm one of the lucky ones

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

How'd they determine that ??.... Cheers Steve

[scottkz Senior Member Find all posts View Profile Close scottkz]

You are indeed lucky ! Water has a higher boiling point under pressure.... So if the system holds no pressure the water is allowed to get hotter

[Farmer Lurker Find all posts View Profile Close Farmer]

water was not obvious in the engine bay and there was no drips underneath which baffled me initially. Mechanic started with pressure test - no drop. then tk test - nothing. Mechanic took it for a run and on return felt the end of the overflow tube (the little black elbow bit) which was a bit damp. ordered new cap, took it for another run and water level didn't drop....happy days.

we were freaking out at the potential expense and family been stuck at home with no wheels...... my 3 year old gave the car a cuddle when i got home. love our prado

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

I hope that was your problem but I'd still be keeping an eye on the level. I had the TK test done on mine and at first showed nothing. Had thermostat replaced, probed and rodded the radiator, checked viscous coupling on fan, new radiator cap. Was still coming out radiator cap into overflow bottle then would overfill that then spew out on the ground which indicated pressure but from where ?? We had done TK test. Then figured while running around town no issues what so ever get her out in the highway/freeway doing 100/110/120 then pull up she'd be bubbling and gurgling out the overflow. It was at this point we decided to do the TK test (bit dangerous being hot but wanted to be certain) bingo come up showing exhaust gases in the test which indicicated either cracked head or damaged gasket, I knew which one is was going to be. Cracked head 4k later. Reason the TK didn't show up first time was engine wasn't hot enough just running around town, give it some and get her working was enough for the head to expand enough where the crack was and let the gases flow lol. I hope yours is as your've pointed out and was just the cap......cheers Steve

[Farmer Lurker Find all posts View Profile Close Farmer]

Good advice Steve, I will be definitely keeping an eye on it. To get home I did take it for a run down the express way but am still a bit wary. Thinking s low coolant alarm would be a good investment...now where was that thread?