Notes about Morgan +4 Over heating problem.

Notes about Morgan +4 Over heating problem.

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Overheating

wibble

First signs of a problem.

Suddenly and with no other apparent symptoms, engine temp started to rise slowly. Normal operation for the previous year had been 80 deg C for most of the time rising to 100 in hot weather and stationary trafic, this was never exceeded. The rise was slow but steady when stationary but was arrested and the temp returned to near normal when moving swiftly. Over the next few runs this problem seemed to get worse. On inspection water loss was seen, this was assumed to be the cause of the problem and so the symptoms were ignored. Next it was noted that not only was the temperature rise not cured and that water loss was getting excessive (2..4 liters per run !) other symptoms were becoming noticable.

Symptoms of problem

Rough running from start for 2..4 mins and after a short break when hot.
Massive loss of water with no trace.
Bubbles (lots of small ones) in water in expansion tank, when hot
Expansion tank always "full" to the top when inspected after a run.
If expansion tank is opened soon after stopping, not only is it "full" but the water seems to have a slight skin of bubbles.
Sudden and unexpected temp rise - no fan operation. (120deg C etc)
Slight hissing noise when engine stopped after a run, coming from radiator expansion tank.
Drivers right leg seems to be hot, close to outer wall - (steam from expansion tank overflow heating footwell wall.)

The only way that much water could posably be pushed into the expansion tank was if some gas was trapped in the cooling system, water simply does not expand that much.
The first reaction to this was to fill the system from the highest point looking for all other points to overflow. I chose the Top coupleing of the heater unit for this, fortunately this is easy to get to.

Interesting things about the cooling system.

Easy place to fill from the highest point.
Bend the hose up,
Remove the radiator and expansion tank caps.
Fill the system from the upturned hose until the Radiator is FULL.
Adjust the level in the expansion tank and replace the cap.
Fix the radiator cap firmly in position.
Continue to fill until coolant (water to you) comes out from the open pipe at the top of the heater unit.
Remove the funnel, replace the jubilee clip over the pipe and reassemble (ram it over the pipe and do up the clip.)

Ram a funnel in the hole.
Place a cup beneath the open pipe.
Note: I put the jubilee clip back on - in case I forget in the excitement of re assembly !

Remove the caps from the radiator and the expansion tank.
Then caushusly fill the system until the radiator is full (to the very top).

View radiator and expansion tank - sans caps.

Note the Fan and fan thermostat (right at the bottom of the radiator) and the fan wiring (double ended bullet joints (push fit). Keep the contacts clean.
BUT NOTE - the fan thermostat is a PLUG that sits in a simple "Mk1 hole" at the bottom of the radiator. If you take it out (say, to make it easier to clean the contacts) be prepared for large quantities of water to follow.

Top view of fan thurmostatic switch (bottom of radiator).

OTOH this is a good way to drain the system, use a piece of pipe (angled down) and a cork (or lump of "gorilla snot" (silicone sealant) and the water is easily directed into a bucket.
This is a LOT easier than trying to wrestle the hoses off then ducking the torrent.

View from below of fan thurmostatic switch.

The cylinder that was causing the problems.

Note the non uniform surface texture of the piston head.
The coagulated deposits, showing signs of organic polymerisation.
The wet look of the surface.

The Spark Plug.

Once more, the non uniform surface texture and coagulated deposits, showing signs of organic polymerisation.
The rust-slime colour on the surface or the ceraminc insulator

After whipping the top off (I got the local Rover dealer to do this)
we find the culprit.

I am told that the damage is as it was found and was done by water and exhaust gases and not with a small screwdriver !

The engineer also offered the comment that the T16 (old engine) could be run for quite a while without water before doing serious damage.
On the other hand, the newer Rover units would probably not last five minutes.

I should consider myself lucky, although as I took the car in half a day early (thanks to the man with the low loader) it got seen early because of a cancellation AND the weather was perfect, warm and sunny when we delivered the car but was persisting it down first thing this morning (when I should have taken it in) I suspect I have used up my entire years supply of luck in one hit!

View of erosion pathway between cylinder and water jacket.