With the age of the old pump and the fact it leaked from the electrical part just by a new one and gate valves fit it together making sure its pumping the right way, you can undo and turn the body so the elec bit is the right side, drain it down and swap as one the old pump will not be...
The leaver type are ok but do not even think about the ones with a ball and screwdriver slot they are 99.9% guaranteed to leak if you turn them after a few years, i wont even try just drain down and replace :(
All new are supposed to be energy A rated, to do this the electronics in the pump knows how much power it required to move x amount water as the thermo valves on the rads shut of this puts a restriction on the water flow causing the to be under more load so it backs the power of as its not...
Never seen just the core only the whole pump, you can swap the whole thing if you want to but the big nuts can be a pig some times, if you have a spanner or adjustable big enough you can try.
No there is a large o ring on the pump motor, its an easy way of changing a pump if access is not good or the valve nuts are well corroded on, it has been known to undo the nuts with a hammer and chisel or even hacksaw.
As you have a Grundfos pump if you get another Grundfos you can turn it of at the pump valves and undo the four allen bolts and just remove the head and swap it out the new one will be flow sensing A rate but will wire up the same.
a 15-60 is same size just more omph
That valve is a honeywell 3 port on a y plan system, the little leaver on the bottom manually moves it over to heating you push it over then let it come back to hook in the little slot try that and if heating works the syncron motor is gone not so easy to change as its facing away from you but...
If you have a valve that the boiler feed goes to in the middle and a pipe out each side for hot water and heating then you a Y plan set up if its a honeywell valve with a silver metal top is the leaver at the end loose when heating is on if there is resistance against a spring then the syncron...
I have been informed by Alan his son that he passed away yesterday after a very short illness, he joined LZ september 2006 so has been on here a long time with lots of helpful input he will be missed
RIP Tony
You have an old style gravity hot water pump central heating system are you sure the pump is working correctly, just because it is turning dose not mean it is working with any omph.
Hows the fluid level it needs to be topped up with engine running as the brake booster will drop the level and the clutch out let is high up, never had issues how about an easybleed kit.
Its steep because they cut to much of the bottom rung, you alter the the top stays to limit the angle the hatch comes down then measure from the second section down to the floor and trim the bottom section to suit , i have fitted a few