Normal operating temperature for your engine is about 75 C. If you are running colder, you are losing efficiency, and if it is appreciably hotter, you can get into trouble.

If your engine runs too hot consistently and overheats or boils on a slight grade or on a hot day, there are several possible causes. The first things to check are the most obvious and the easiest. First be sure there is an unobstructed flow of the air to the radiator. The central location of the fog light, as furnished on most Morgans, is a major contribution to overheating in this area (as are badges and badge bars, GoMoG Webmaster). Bc sure your radiator passages are not full of bugs and dirt.  Clean then out with a hose from the back. From this, go to your water system. Start by checking the condition ot the water in your cooling system. If it is full of rust and dirt, drain and flush the system until you are sure it is clean. If it is excessively dirty, it is a good idea to have the radiator back—flushed to be sure. Next, look for leaks around and under the radiator, at various hose connections and around the water pump and petcock on the engine block. When checking the hoses, be sure they are not soft when you squeeze them. A hose may look O.K. on the outside but can have a loose flap or blister on the inside restricting the water passage.

If everything is OK so far, check the fan belt to be sure it is in good condition and not slipping. The next step is to check the water pump and thermostat. Remove the radiator pressure cap and rev up the engine. If the water pump is working properly and the thermostat is not stuck closed, you will see a turbulent condition on the surface of water. If  the water remains still, it is usually a bad thermostat since pump failures are relatively rare.. Remove the thermostat and repeat this test to check the pump itself.

If your engine still won't run cool., start checking the fuel mixture and check for leaks around the induction system. If your carburetors are set too lean, or are excessively dirty, they will cause hot running. Check all the joints in the manifold (intake system) by smearing a little engine oil on the joints (one at a time) and rev up the engine. If your exhaust shows blue smoke, you have a leak and should tighten the joint, or replace the gasket. (You can also check this with a can of spray ether, or "Quickstart spray" [check the label], with the car idling VERY lightly spray the joints..if the idle changes you have leak..GoMoG Webmaster).

Another common cause of overheating is retarded ignition.  This can be due to poor timing or sticking of the automatic advance—retard mechanism at the base of the distributor. The vacuum advance can cause this by a leak in the diaphragm too.  I have found that this retarded ignition is quite a common situation. Many mechanics will set an engine slightly retarded if the customer complains of "pink- ing".  Usually it is caused by lugging the engine at too low revs.

Another contribution to a  hot engine can be an oil which does not have enough viscosity index or will foam, and lose its conductivity accordingly. If you do a lot of stop and go driving, it pays to use a a premium quality multi-grade oil. If you have been using a 20 wt., use a 10-30, if you have been using a 30 wt., go to a 20-40.

If you have done all  the proceeding and still have a hot running engine, start looking for burned valves warped head, and other major problems.
 

MAKING A MORGAN FOOT VENT
An excerpt from Robin King's Column
June 1972 FORMAT, the newsletter of  the Morgan Plus 4 Club
Plus 4

Ventilation: Ah ha! you ask does a Morgan need more ventilation? Yes, most assuredly, at least in hot weather. Have you forgotten your feet? On a hot day, with a hot engine (perhaps even overheated) don't you feel like you are feet-first in the Witches oven?

My remedy...foot air vents, and the really do make a difference. I had a devil of a time locating a place to put holes without seeking engine heat or chopping up the exterior. After several inspections, voila!, there is a spot about 2 inches from the firewall and 6 inches off the floor. Perfect! It comes out above the Z section into the fender flashing and on the outside, hidden from view under the fender.

Fresh air flows alongside the frame and into the vent and onto your feet. The hole I made in mine is about 1 1/2 inches in diameter. For cooler weather, I have made a sliding gate that closes the opening. There now, for you creatures that desire small measures of comfort, try some of these ideas. Every little bit helps.

REDUCING THE HEAT IN THE CABIN
by Lorne Goldman

Much of the heat in the cabin comes from the gearbox cover and secondarily from the firewall. The easiest (and most expensive way) of curing the gearbox cover heat is to have a new cover made and have it lined with 1/2 inch of foam.

Click the image for the J.C. Whitney source

Another method would be line the gearbox itself with Mylar faced foam sound/heat insulation. This is thinner at about 1/4 inch and, if your cover has stretched over time, or if you oil it well to stretch it a bit, you can make it fit and fit well. This materiel is also excellent to place on the passenger side of the firewall between the carpet and the metal surface.

It is also an excellent idea to remove the gearbox materiel cover over the gear lever, (you must remove the gear knob to do this, find a large tapered rubber cone (often available at a plumbing or auto store), push this down around the top of the gear lever to act as a dam for the hot air on your hand.

One other tip...never ride in the Morgan on a hot day in shorts or a light dress.