The Root Cause in Morgan Cars (AI)
Thermal shock occurs when a material undergoes rapid, uneven temperature fluctuations, causing different parts to expand and contract at different rates.
The Valve/Thermostat Failure:
In the CX-generation platform, early Electronic Control Unit (ECU) software poorly managed the cooling control valve.
The Shock Event:
When the cooling valve or thermostat suddenly cycled fully open, a massive rush of hot coolant or trapped steam slammed into the cold, all-aluminum radiator.Structural Stress: This rapid temperature spike forced localized sections of the aluminum to expand violently while neighboring segments remained cool, creating intense structural fatigue.
Key Impacts on the RadiatorCracked Welds and Core Failure:
The intense internal stress targets the weakest points—typically the edge of the welds where the aluminum tanks meet the cooling core
.Pressure Spikes:
The sudden arrival of steam causes mechanical and physical pressure shocks alongside the thermal shock. This expands the small, tightly sealed system beyond its limits
Chassis Aggravation:
Because traditional and modern Morgans experience significant chassis flexing and vibration, a radiator already weakened by thermal fatigue will crack much faster than one in a standard production car.
Total Coolant Loss:
Once a seam splits, coolant rapidly escapes. Because the Morgan cooling system runs at high pressure with a small header tank, a thermal-shock leak quickly leads to severe engine overheating.
The Solutions and Fixes
:ECU Software Update:
For CX-generation cars, Morgan released a mandatory dealer software update and Swirlpot retrofits. This update reprograms the cooling valve behavior to open gradually, bleeding heat into the radiator smoothly to completely eliminate the thermal shock event.
I spoke to quite a few people at Malvern before buying my CX on this issue, and they indicated,. there are many earlier cars in regular use, not just garage queens, still on their original rediators. Doesn't help those who are still experiencing problems, with their rads, but unfortunately like my clunking it maybe something \I have to live with, and may over time require an expensive fix...
Last edited by JohnHarris; 05/08/26 08:09 AM.
