Imports and over heating.

[Ben]

Im not sure what the bigger toyota engines are like for over heating? But the 2.4TD and 3litre (1KZTE) imports suffer with over heating and cracked heads.

According to Roughtrax website its to do with the viscosity of the fluid in the viscous fan.

This is what the website says:-

Previous couplings fitted to Japanese Imports had a different fluid which caused the fan to spin less as their speed limit is approx 50mph, in the UK the couplings were filled with fluid that would cope with our 70mph speed limits. This is information that RoughTrax has obtained from Toyota Tech.

Id never thought of it before, but something must be to blame for all the cracked heads which imports seem to suffer from.

http://www.roughtrax4x4.com/?doc=16&cid=149&vid=918

 

[Rob]

That would explain why there are 2 different viscosities of viscous fan fluid available from toyota

 

[Dan W]

Do you think this applies to all import Toyotas? I only ask as my 3.0 litre surf recently has had the head done but it doesn't mention the different fluids issue on the kzn130 viscous fan page.

 

[Zeusv8]

My kzn185 3 ltr cracked too, no likey motorway speeds!

 

[Graham]

Perhaps the way forward is to remove the troublesome viscous fan.
Replace it with an full size electric fan.
Then fit a two thermo-switch's, one in the lower radiator pipe and one in the upper, connected in parallel, so either activates the fan and a dash mounted running indicator light, set at your chosen temperature.
As a back-up, I would have a second fan feed from a toggle switch.

Gra.

 

[Crushers]

no, it is the basic head design.
number 4 cylinder develops vapor buildup and the head cracks
i have run fixed fans in the past with the cracking still occuring, the viscous fan is not the issue ... of course if the sillycone is breaking down then the issue doesn't help the overall demise of those heads

 

[adrianr]

ON subject of fans in general Gra - i recall JW commenting that he tried elec fans on his 80 and removed them since the airflow with the viscous unit was far more effective.

 

[Jon Wildsmith]

The ATF temps stayed much higher with the electric fan fitted as well.

 

[Cptsideways]

Codswallop I'm afraid, at 50mph or 70mph the fan will be free running in the wind anyway.


To give you some Idea my JDM 80 IHDT has the viscous removed since January, it tows all day long in any weather & the water temps never get above normal. I'll stick it back on off road stuff but otherwise the airflow through the rad whist driving does all the cooling it will ever need.

 

[Ben]

Codswallop I'm afraid, at 50mph or 70mph the fan will be free running in the wind anyway.


To give you some Idea my JDM 80 IHDT has the viscous removed since January, it tows all day long in any weather & the water temps never get above normal. I'll stick it back on off road stuff but otherwise the airflow through the rad whist driving does all the cooling it will ever need.

Are you relying on the standard temp gauge?

 

[clivehorridge]

If the rad's not blocked that's OK while you're doing 50 to 70 mph but when you're in traffic, you will boil up. The fan is for traffic, not pretending you're a spitfire.

When the gel in mine dried up, it ran too hot in traffic meaning boiling up on a 40 degree C + summer day, but was just fine on the open road. My problem was it cost almost 300 Euro for a replacement.

The new one works perfectly now, anyway

 

[Crushers]

you can open up the viscous fans and replace the oil inside. $4 a tube and it take 2 tubes ...
much cheaper than a new housing.

some have luck with this, some don't. still worth the try.

 

[Andrew Prince]

It's engine design that's at fault. In South Africa, the KZ-TE's crack heads like it's going out of fashion and average speeds are much higher than the UK, so I doubt they put in a different viscous fluid grade. It also happens to be hotter in South Africa... 2+2 makes?

The 4.2 diesels are known to be "over-cooled" in terms of rad design and cooling galleries round the engine. Cracking heads is virtually unheard of and they all run viscous-coupled fans in OEM set-up. Safe to say it's an engine design issue on the KZ as Wayne said. You can get after-market heads AFAIK that have improved coolant galleries and reduce the incidence of cracked heads.

 

[clivehorridge]

The 4.2 diesels are known to be "over-cooled" in terms of rad design and cooling galleries round the engine. Cracking heads is virtually unheard of and they all run viscous-coupled fans in OEM set-up.

It's good to know that my old girl's engine is "over cool"... that's cool
She's also got that verical airflow roller-blind arrangement, useful here when it's -20 or less in the winter.