Help please - 1HZ landcruiser overheating!

[Robbos_Toyotas]

Hi all
My uncle has an issue with his hzj75 landcruiser overheating. The thing is running great, has a new radiator, new injector pump, water pump etc etc but it just overheats when you start to work it hard.

For example, towing a car trailer up a hill last night it almost boiled - and the temp goes up almost instantly! But then as soon as its not working as hard, it comes back down just as quick!

its been happening for a while now and is starting to become a nuisance...

Is there any problems i should be pointing the finger at? timing perhaps?

Thanks
Blake

[fixeruperer]

thermostate ?

being diesel its has no ignition timing only fuel timing.

[Bananaman]

I'd have thought something relating to the thermostat not opening fully with the symptoms you describe, i'd replace it just in case if you haven't already, cheap insurance

[2jzhilux]

possibly a crack in the head
around the precomp chamber
they do this quite a bit

[Robbos_Toyotas]

yeah i was thinking either cracked head or thermostat - for his sake i hope it isnt a cracked head as 1HZ aint a cheap motor to fix...

[2jzhilux]

id definately try thermostat first though(cheaper than head)

[Robbos_Toyotas]

turns out it has a new thermostat - so i guess its not looking good for him...

[BeRad]

engine been freshened up lately?....or hasnt been given a good work out since he got it or something?

[Cruiser97_80]

Does the fan get louder when it gets warm, because it should.
Fairly common problem with the viscous coupling fans on 75's.
2 ways of fixing 1. buy a new coupling, 2. You can buy the special oil that goes into the fan coupling from toyota, 1 bottle is 10ml or something like that just add 1 bottle 2 what ever is left in the coupling. This is a fair bit cheaper but does not always work. If you want extra cooling power add 2 bottles, but this will make the fan work hard all the time will make it sound like an aeroplane taking off when giving it a bit.

[Robbos_Toyotas]

nah it runs a huge ass commodore electric fan, which is doing more than its job at cooling the motor down. its also got a 10" fan on the front to aid...

[Robbos_Toyotas]

engine been freshened up lately?....or hasnt been given a good work out since he got it or something?

nah this has been happening and we've been trying to fix it for a year...

[off-road]

Sounds like everything has been done except head. Symptoms are same as blocked radiater (on the outside fins-they get full of grass seeds up here.) but if radiater is new its probably not that.

[Robbos_Toyotas]

Sounds like everything has been done except head. Symptoms are same as blocked radiater (on the outside fins-they get full of grass seeds up here.) but if radiater is new its probably not that.

nah brand new 4 core radiator a week ago.

How can i test to see if it is a crack in the head? Will a compression test show it or do i need to take the head off?

[lojik]

If head is cracked then you could be getting combustion gases being pushed into the water.

A shop can put a meter over/in your radiator filler and test whether combustion gases are present in the coolant mix.

[Robbos_Toyotas]

If head is cracked then you could be getting combustion gases being pushed into the water.

A shop can put a meter over/in your radiator filler and test whether combustion gases are present in the coolant mix.

will a compression test show it tho? i have a test kit of my own therefore i dont need to pay a mechanic thats all...