Water level in a Cummins - one for Latestarter

[superheat6k]

Cummins 6BT5.9M - With the expansion vessel attached to the cap overflow I assume it is correct to completely fill the freshwater system to the brim, without any level / air gap just below the filler cap.

Unbelievable amount of gunk came out when I flushed the engines today. Clearly not done for many years by the previous owner.

 

[Latestarter1]

Cummins 6BT5.9M - With the expansion vessel attached to the cap overflow I assume it is correct to completely fill the freshwater system to the brim, without any level / air gap just below the filler cap.

Unbelievable amount of gunk came out when I flushed the engines today. Clearly not done for many years by the previous owner.

B Series is incredibly sensitive to getting an air bubble behind the thermostat if filled too fast, for example with a hose.

Fill to the neck and leave cap off. Start engine and run until warm, likely you will get a 'gloop' as any trapped air is dispersed and level drops slightly, leave it there.

Following draining and re-filling if your pressure cap starts blowing like a kettle during a run do not panic, carefully remove cap after cooling a little and run engine without the cap. Airport ground power units for starting jet engines seem to suffer the most as they invariably fill engines with a hose, rush, rush, following coolant change and I have known them change head gaskets trying to eliminate the issue!

Some Thornycroft motors had an expansion tank on the side of the block, being part of British Leyland in the past they used the nice little brass expansion tank off Mini/1100 cars.

 

[superheat6k]

B Series is incredibly sensitive to getting an air bubble behind the thermostat if filled too fast, for example with a hose.

Fill to the neck and leave cap off. Start engine and run until warm, likely you will get a 'gloop' as any trapped air is dispersed and level drops slightly, leave it there.

Following draining and re-filling if your pressure cap starts blowing like a kettle during a run do not panic, carefully remove cap after cooling a little and run engine without the cap. Airport ground power units for starting jet engines seem to suffer the most as they invariably fill engines with a hose, rush, rush, following coolant change and I have known them change head gaskets trying to eliminate the issue!

Some Thornycroft motors had an expansion tank on the side of the block, being part of British Leyland in the past they used the nice little brass expansion tank off Mini/1100 cars.

Excellent advice as ever - thanks. Mine are Thornycroft but have an opaque plastic tank.

 

[Latestarter1]

Ah ha, same size tank but the later plastic one from Mini Clubman/1300