Hi Carl,i run both an lj70 2.4 and a surf(the 3.0td) and to be fair i,ve never had any overheating issues.i,ve run and totally abused 2.4 surfs in the past and never had any over heating issues but look on ebay and you,ll see a lot of the 2.4 surfs either have overheating problems or have recently had a new head and/or water pumps and radiators.Thers a lot more surfs knocking around than lj70s but its quite likely they have the same potential problems.theres a lot of thoughts on this matter on the landcruiser/surf forums and to be honest i,m still not sure which are opinion and which are fact.this is what i,ve read in the past and you can make of it what you will
1-Does this engine overheat first and crack its head or do cracks appear and cause the engine to overheat?The theories range from
a)the 2L cylinder head not being quite up to the job when Toyota bolted a turbo onto it
b)a bad batch of heads from manufacture with an inherent design flaw
c)the import motors from Japan being set up for a different climate and running too hot from the off when they come over here
d)people just not maintaining the cooling system or checking coolant levels for any early warning of potential problems
e)the early LJ 2.4,s with mechanical pumps(1988 T0 1990 i think) being better than the efi controlled later engines with regard to head cracking
i,m in the process of tweaking my lj70 for off roading which involves an intercooler,running much higher boost and overfueling it like a beast so in a couple of monthes il probably be in a position to tell you exactly how much abuse a 2.4 head can take!There,s a lot of people on this forum with way more mechanical knowledge than me who may have more informed input on this matter