Violent Coolant Spray From Back of Engine - Deteriorated Heater Hose at Union Bolt

Antifreeze was violently spraying onto the back of the engine and firewall on an 88 NA 7M-GE MK3 Supra. The leak was not a slow drip like a head gasket but a forceful spray.

The coolant hose at the union bolt on the back of the cylinder head had deteriorated from decades of exhaust-side heat cycling. The hose had developed a huge bend and was almost completely blown out. This is a common failure point on 7M engines where exhaust heat degrades the rubber hoses over time.

High confidence — Original poster confirmed this resolved the issue