We have EGT on most of our earth moving gear. The EGT when it starts to climb can go very rapid very quick if you are under very heavy load conditions. 1250 is probably a reasonable limit. I would be a bit concerned running an alloy headed motor above that for long. Those sort of temps would definitely remove any carbon build up as well as maybe a bit of metal in time. You risk surface boiling the coolant in the head as well.

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Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving