lshobie said:Is Canadam the same guy as Previa Diesel on this board - the guy selling the HZJ77 in the classified section?
Answer: No. I'm on the Island, not in Prince George.
I have a Surf with the same 2LTE engine though and from reading the Australian forum in particular, it seems there are a number of possible reasons for head failure:
1. Clogged cooling systems
2. Low coolant levels - the 2LTE is particularly prone to developing airlocks reportedly. Do this if you have a 2LTE: http://www.allhead.com.au/cooling.html
3. Fan clutch failure - who would notice this?
4. Restricted water passages in head gaskets - some report no more overheating after using gaskets with coolant holes the same size as those in the head and block. Why would Toyota use gaskets with reduced holes? Has been suggested this was a last minute attempt to fix a design flaw in the head. When you have a thermal problem like this cracking, there are two possible approaches. Either you attempt to keep the head cool all the time by allowing high flow or you attempt to prevent sudden changes in temperature by restricting coolant flow. Since iron does not have the thermal conductivity of aluminum for example, you might think it would be better to reduce the flow and prevent rapid heating and cooling - which is what causes castings to crack usually, esp. complex castings like cylinder heads that have a lot of unequal stresses. It may be that Toyota called this one 'wrong' and the better option is to allow higher flow and prevent the head (which is reportedly 'thin' and therefore more conductive) from ever getting too hot. BTW, I never fully open the heater vavle on my Surf when the engine is hot - I don't want the thermal shock of a slug of cold water hitting the head. (maybe I should check the actual routing of the pipes!)
5. Driver abuse, particularly dangerous with high ambient temperatures like Australia. These engines are not happy over 3000rpm. They are not gassers and cannot be driven as such. People used to driving gassers expect to just put their foot down more when they are 'not going fast enough'. You can't do it with a diesel.
6. Design flaws in head - I've never seen any photos or drawings to support this, but everyone seems to say that the reportedly heavier/thicker 3L (2.8l) head does not have these problems.
I would have a good look at the IP and see if the yellow paint and lead seals are still intact. Does the fuel screw look like it has been adjusted? Some folks like to mess with the settings for more power. I'm not aware of anyone in NA who has the diagnostics to tune a 2LTE, therefore better not to mess with it.
Finally, adjust your mirror so you can keep an eye on the tailpipe, when you start putting out black it's time to ease off.
The 2LT is a pretty tough engine, I had one of mine (worn engine) run away on me three times before I learned how to drive it and it still ran OK afterwards. A runaway diesel is quite an experience.

and i'll buy you a beer!