Maybe stress from alternator or other mounts? Not sure the UK 185 is the same celica (3S-GTE?):
In the vicinity of the alternator mounting the cylinder head is prone to cracking. 185s were fitted with a different style engine mount and an additional stay to help prevent this from occurring - picture. Click here for a picture of a cracked head
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Hi,
>
> I was hopeful that someone might be able to give me a different insight
> into a problem that occurs with my dads celica.
> The car has an issue where that around every 150000kms it cracks the
> head into either the number 2 or 3 exhaust port. the engine is a 3S-GE
> with TVIS. The only mods are a cold air intake to feed the factory air
> box and a set of tri-Y long primary exhaust headers.
> The car has done it to 3 heads so far and always the same problem. The
> engine runs fine when the head cracks and still produces full power it
> just pumps the radiator into the exhaust with a cloud of steam.
> It has also has had the engine changed the last time it happened to a
> jap spec motor. The car has had the water pump, the thermostat and the
> radiator replaced that the car never has any heating problems.
> It usually has the oil changed every 5000kms with the longest it's been
> being 7000kms. The car does a lot of highway driving occasionally towing
> a lightly loaded trailer. On average it does about 800kms per week.
> About the only thing that has happened to the car other than normal wear
> and tear is that the heat from the exhaust warped the blades on one of
> the radiator fans.
> The only thing I can think of is that the head gasket it not allowing
> correct water flow to the head and causing a hot spot which causes the
> cracking, But I'm not convinced this is the cause and the head gaskets
> used are identical in water flow holes to the factory Toyota one. >
> If anyone has any ideas as to what could be the cause I'd be grateful to
> fix this problem as my dad would like to keep using the car for work for
> as long as possible.
>
> Nick