Disappearing Coolant and Rough Idle - Failed 90-Degree Coolant Hoses Near Exhaust

Coolingintermediate✓ OP Confirmed

Problem

Coolant was disappearing after about a week of daily driving on a 7MGE with 109k miles that had previously had a full rebuild (head machined, all gaskets replaced). Sweet caramel smell and smoke visible underneath the car. Rough idle developed over time.

Coolant level dropping over a week of daily drivingSweet caramel smell from under the carVisible smoke underneath the car while drivingSmall drips visible behind the head near the firewallWhite smoke on cold start that cleared when engine warmed upRough idleBlack specks in coolant when flushing radiator

Root Cause

Multiple deteriorated coolant hoses had failed. The primary leak was from the infamous 90-degree bend hose that runs under the exhaust manifold (which gets heat-soaked and fails over time). Additional leaks were found at the union hose connecting to the 90-degree hose and the hose running from a heater hose to the throttle body. The hoses were original 30+ year old parts that had been damaged from a previous overheating event 12 years prior and were never replaced during the rebuild.

Confidence

Moderate confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted November 2022 on SupraForums.com