Charles Durning's Journal --
On MG Experience there have been some discussions about the availability for a correct thermostat for our MGB engines. The originally available thermostat had a blocking ring for the water bypass is the head. The currently available thermostats do not. At issue here is the belief that there is too much coolant flow through the bypass when the thermostat is open. Some have expressed that our engines run hotter because that water bypasses the radiator. To solve that issue, some folks will install a blocking sleeve that is available from the usual suspects. The problem with that solution is the thermostat can no longer be used. With some modifications to flange on the blanking sleeve and the thermostat. The thermostat can be used. Going back to my Small Block Chevy days, we would just thread the bypass port in the block or the water pump and install a plug. Then would drill some small bleed holes in the flange of the thermostat. I never has an issue with doing that. I would go one step farther and attach a bleed hose that would allow better circulation at the back of the head. When Rover took over the Mini production they just eliminated the troublesome bypass hose between the front of the head and the water pump on the A+ Series engines. They plugged the port in the head and eliminated the hose nipple on the water pump. I made that change when I overhauled the engine in my Morris. In thinking about that, I decided to see what can be done on the B Series engine in my MGB. There is a readymade solution right from the factory. Just plug the port between the head and the block. As fate would have it, the drilling in both the head and block are just the right size for a 7/16-20 set screw. Installing the set screw as a plug will defeat the bypass function and will force all of the coolant to go to the radiator. Then just drill some bleed holes in the thermostat flange and you’re all set. Something to ponder the next time the head is off of your engine.
Posted 2024-02-14 05:31:51 by charles durning
On MG Experience there have been some discussions about the availability for a correct thermostat for our MGB engines. The originally available thermostat had a blocking ring for the water bypass is the head. The currently available thermostats do not. At issue here is the belief that there is too much coolant flow through the bypass when the thermostat is open. Some have expressed that our engines run hotter because that water bypasses the radiator. To solve that issue, some folks will install a blocking sleeve that is available from the usual suspects. The problem with that solution is the thermostat can no longer be used. With some modifications to flange on the blanking sleeve and the thermostat. The thermostat can be used. Going back to my Small Block Chevy days, we would just thread the bypass port in the block or the water pump and install a plug. Then would drill some small bleed holes in the flange of the thermostat. I never has an issue with doing that. I would go one step farther and attach a bleed hose that would allow better circulation at the back of the head. When Rover took over the Mini production they just eliminated the troublesome bypass hose between the front of the head and the water pump on the A+ Series engines. They plugged the port in the head and eliminated the hose nipple on the water pump. I made that change when I overhauled the engine in my Morris. In thinking about that, I decided to see what can be done on the B Series engine in my MGB. There is a readymade solution right from the factory. Just plug the port between the head and the block. As fate would have it, the drilling in both the head and block are just the right size for a 7/16-20 set screw. Installing the set screw as a plug will defeat the bypass function and will force all of the coolant to go to the radiator. Then just drill some bleed holes in the thermostat flange and you’re all set. Something to ponder the next time the head is off of your engine.
| Image may be NSFW. Clik here to view.  <A Series water pump compare> | Image may be NSFW. Clik here to view.  <another view of the threaded port> | Image may be NSFW. Clik here to view.  <another view showing the angle> |
| Image may be NSFW. Clik here to view.  <Taping the port> |
Posted 2024-02-14 05:31:51 by charles durning
