overheating problem

[michael36]

I have had a series of problems on a Glowworm Fuelsaver 40B Mk2 boiler, replaced gas valve, thermostat, and pilot valve.
The problem I now have is boiler overheating, the system fires up for approx 1 minute then the over-temperature stat shuts down the boiler and pilot, the water feed and return pipes from the boiler get extremely hot in this short period. The pump is running but sounds noisy, there is no room stat on the system.
I would be grateful for any help or advice.

 

[ollski]

If you have ruled out any air locks in the system I would go with a faulty pump especially if it is noisy.