TD Prado overheats

So where does the sensor for the gauge go? Is it using a screw in VDO type or a thermal probe in a hose somewhere?

I used the hoses that went to and from the throttle body heater. Figured I don't need that in WA. :-)

So basically there are two small coolant hoses, one that comes from the block and into the throttle body. The other comes out and returns back to the block.

I just disconnected them, screwed the probe into a brass "T" peice and clamped the two hoses to that. Then I just put a dob of silicone over the inlet and outlet of the throttle body heater. Never noticed any difference whatsoever from disconnecting the throttle body heater either. Was an easy installation. Hardest bit was getting the probe through the firewall as I already had air hoses and 2 bits of 4 gauge electrical wire going through, not to mention the dozens of smaller wires that I had to put through. LOL

Here's a pic of the throttle body for you:

She's not really that hi tech, the motor's similar in age (design wise) to your old 80. Mine's a 95' and they started using the 1kz-te in the surf's in 93'.

If it had a cast head it still may have cracked from being overheated, but they are generally a little more robust as they the alloy is generally a little more brittle.

The question I'd be asking is why did it overheat? I doubt the cracking of the head would have caused the overheating, more like what ever caused the overheating resulted in cracking the head.

Blocked radiator, stuck thermostat, water pump???

"cast iron" that should have been.. :-)

Of course, that's my worry. Getting hot is a symptom, so where's the cause?? Off to Hume Off Road (ACT) on Saturday - sharpening the credit card now.....

The alloy gods may be smiling and it may only be the gasket.....

The surf has a different radiator to the prado, so I'm not sure how relevent this info will be, but these are the typical causes of overheating for 1kz-te surfs.

Radiator blocked. (obvious one).
Viscous fan not working correctly (even if it sounds like it is, it may not be fully locking in and slipping)
Gearbox - ATF low or working the gearbox too hard (in the surfs the bottom tank of the rad is where the heat exhchanger/atf cooler is).

Generally with all of those it's normally only hard acceleration for long periods that causes it to overheat, but there will be no warning that it is getting hot until the guage all of a sudden shoots through the roof.

The prados have a 70 degree C thermostat so your running temp should be around 71/72 degrees c. Depending on how efficiantlly your rad is working your rad shouldn't get heat soaked until about 30 degrees c+ outside temp cruising at 110kph++, even then all that will happen is your running temp will increase up to what ever temp the viscous fan is set to cut in, then it'll drop back down again.

When there is something up the bleep ter it get's heatsoaked and runs hot (not that you would know as the temp gauge would still be on half). Then it doesn't take much (just a longish hill or some soft sand or whatever) to bring it over the edge.

For example, the surf has a 90 degree thermostat. It sits at 91 normally, highway cruising 30 degrees + it stits at about 98/100 degrees, if there are hills, overtaking or the outside temperature get's hotter the viscous fan cuts in at about 102c then it roars its nuts off until the temp drops back down to 95c and cuts out, it'll cycle like that on and off all day if it has too.

But I can still get it hot if I'm overtaking up hill or doing some really boggy sand sections because the temp goes up so fast the viscous fan doesn't get a chance to lock in in time and I have to back off until it does and then the temp drops back down again.

Don't know if any of this helps, hope it does! ;-)

Qualified mechanic did have a look - me - since 1982.....

However, don't really feel like crawling around under the bonnet anymore (unless someone is paying me!)

Well, limped it home, couple of stops to check/top up the water. Radiator cap off and the heater running to dump a bit of heat - lucky it's approaching winter in Canberra (apparently). Oil is not contaminated and no indications of water getting into anything else. It didn't lose a lot of water on the trip and the temp stayed just below centre gauge where it always sits. Slight bubbling in the radiator, not geysering like I've seen a Disco with the same problem do.

Fingers crossed on a head gasket 8~/

Bought second hand a few months back, one owner with full service history. It was used as a tourer, sequential receipts from all around Australia every 5000ks(can track where they went!), but it was never used to tow a van as there is no towbar and no indication of one ever fitted. No indications anywhere of previous problems, just one of those mechanical things that can occur.

I would be interested in any info and claims people have had against Toyota for craked heads if this is the case. Of course, the dealer warranty isn't worth the paper it's written on "DOES NOT COVER DAMAGE DUE TO LOSS OF COOLANT" well DUH, what's the main cause of engine failure???