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HOT/COLD Climate head gasket, truth or myth


New Member
May 12, 2022
Country Flag
I have towed 1.5 tons for 150KM in 30C and the engine overheated occasionally.
Due to a balancer shaft bearing failure that cause zero oil pressure i had to take it apart in order to replace the bearings and one shaft.
After removing the head i was amazed to see that most of the water passages between the head and the engine block are blocked by the OE head gasket.
I guess that's a normal sight for the 1KZ veterans but for me it was a shocking first despite building many engines over the years.
The strange thing is that when searching for a head gasket i found some aftermarket ones that do not block those passages... someone mentioned somewhere that the vehicles for the Japanese market are COLD climate tuned and that there's a HOT climate version with another type of gasket (non restrictive).
Could this be the answer to the large numbers of cracked heads ?
All i found is theories and people trying to understand this issue in posts that are a decade old ....
I hope this issue was finally understood after so many years
Please let me know, THX


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I remember reading about this some time ago, but can`t remember where.
If I recall correctly.

There are some channels in the head and block that are there as part of the coolant jacket, but to keep a flow past of the head it isn`t desirable for all of these channels to join up as that could "short circuit" the through flow. The head gasket blocks this.
There is only one type of head gasket, and it is correctly made to block some channels.
Not sure about the gasket but there is a towing thermostat that opens to cycle at a lower temperature . The part number is on here somewhere if you can find it .