[Mgs] Rubber-bumper B cooling system

PaulHunt73 paulhunt73 at virginmedia.com
Sun Feb 9 02:40:21 MST 2020


The V8 (which always had twin electric fans) had been and gone before 1977, and apart from the radiator being in the forward position with a remote expansion tank not much else was the same.

It always amuses me when people scratch their heads like this, the factory knew what they were doing, and they made over 50,000 of them that people have been living with quite happily for over 40 years.

Whereas the V8 had a bung on top of the rad for filling the 4-cylinder has it on the thermostat housing.  Not much is higher than that - except the heater matrix which was always higher.  Nevertheless if you fill it correctly i.e. heater valve open and the front of the car ideally slightly raised relative to the back, or at least level, the system purges itself of air in a couple of heat/cool cycles.

However one problem with filling can be caused by thermostats without a bleed valve or notch, they trap a huge amount of air under that stat in that the rad can be full but the block virtually empty.  I've had one of those and drilled a hole in the outer disc.

All rubber bumper cars may well have cooling slightly reduced as the slots in the bumper are significantly smaller than the chrome grille.  But this may well cause more anguish to the paranoid on the 77 and later models as they have different gauges with a narrower angle from min to max.  That and people with modern cars being used to seeing the temp gauge rock-steady under all conditions unless something is wrong.  I've had my RB V8 on test on a 30C86F day in a garage where the internal temp got up to 41C/106F and whilst the fans were running all the time the temp gauge was still only 2/3rds the way from N to H.  Remember the 'normal' range on an MGB is anywhere from the upper edge of the C zone to the lower edge of the H zone. It's only overheating if it's losing coolant or steaming, and there can be many causes of that where components aren't what they should be.

As for the clutch - yes it can be a pain to bleed, which is why I always use reverse bleeding as it's easier to push air up the pipe and out through the master than it is down and out through the bleed nipple.  If that leaves some in then just wedge the clutch pedal fully down overnight so that any remaining air gathers at the top of the pipe by the master, then next morning release it and the fluid coming back from the slave pushes that out though the master as well.

PaulH.


  ----- Original Message ----- 


  On the '77 - '80 cars, the radiator was moved farther forward (I think to allow room for the V8 engine) so the mechanical fan would no longer have been any use.
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