Steve replied:

Bob I feel that I have had a similar problem with a L/c 4.2 diesel Station Wagon... After a new rad, new Thermo, new pump , and a new fan coupling the problem was solved ... but not until the fan coupling was renewed... reckon it sounds exactly the same problem, temp never rose above normal in city and without load, put all the Camping gear on board and loaded up would still cruise at normal temp, but start up a steep hill or put a bit of pressure on the motor and temp rose above normal, the fan coupling was eventually diagnosed as r/s ! ( there does not seem to be a way of testing these bits, so I replaced it with new) An expensive little lesson, Dealers could not work it out, gave heaps of daft excuses eg, wrong coolant, non factory rad etc..Hope this helps you a little,
steve

Ian replied:

Bob,,,i just checked the fan on my 80 series 4.2 with the motor cold i can freely turn the fan in either direction with just a very slight drag ,i hope this can help you ,,,Ian

Steve replied:

Bob,

4WD Monthly had an artcle on how to add the viscous coupling oil to the fan. Not a very difficult procedure. I can look up the issue if you want. You don't need to buy a new one as they are fully servicable.....and it is a common problem after a few years.

bob replied:

Thanks steve that would be great if you could do that for me . Priced one the other day $450

Rod replied:

Bob, I recently had to replace the fan hub on my 4.5 Petrol, because it had a sweaty leak. Like you say Toyota wanted $500.00. Got mine from Coventrys for around $250.00, came in the same type of Toyota packaging etc.

bob replied:

Rod

Can you please explain where Coventry is, as I am based in Brisbane. Do they have an email address?
Cheers Bob.

Kev replied:

Hi Bob this overheating problem you have is fairly common with toyota's before you spend $500 on a new coupling, try having your radiator cleaned professionaly, which involves removing the top and bottom tanks {make sure they do this as some places only "powerflush" which is a waste of time} For some reason Toyota put in a inhibitor at manufacture and after a few years this turns to cement which will block off enough core tubes to overheat your engine when you are driving up a hill.this should cost about $100.Also check your themostat make sure it is a genuine toyota one, i've had nothing but trouble with non-genuine cooling componants.cheers Kev.

Steve replied:

Bob,

The article was in the March 2002 edition of 4WD Monthly. I can fax it to you if you contact me offline as sjcampbel@optusnet.com.au