For a coolant recovery system to work properly, the radiator cap must be a
"coolant recovery cap." These caps are different from a regular cap in that
they have a second seal or gasket just under the top of the cap that seal
the system to the top of the radiator neck. A normal cap only seals with
the spring loaded release valve which seats down inside the neck on the flat
seat you can see about 1 inch down (on a Morgan) below the top of of the
radiator neck. There are two different depth radiator caps in general use
(at least in the normal size cap we are talking about), these are 3/4 inch
and 1 inch. All coolant recovery caps are made for 3/4 inch deep radiator
necks. All Morgans made before 1970 , I think, used 1 inch deep necks and
caps. The Morgan radiator used in all +4 and 4/4 cars before 1970 were
designed to use 4 # caps. I my experience, using a cap of higher pressure,
even 7 # will cause a tendency for the radiator to spring leaks at the
corners of the core. This was a problem that my car had even when it was
new, with a 4# cap installed. If you are using an original bellows type
thermostat with the ring that closes off the by pass port when the
thermostat is opened, using a pressure cap of higher than 4# will cause the
thermostat to fail. This I also know from personal experience!
We have made a normal 4# cap into a recovery cap by making a thin rubber
or teflon gasket an installing it inside the top of the radiator cap so that
the system will be sealed and thereby draw coolant back into the radiator
from a recovery tank as the car cools down. This does work. The recovery
tank should be mounted as high as possible because the vacum generated as a
4# system cools off is not very high.
We have found MANY English radiator, not just Morgans, which are
completely clean, are in good mechanical condition, which competent
radiator shops will say heve nothing wrong with them, but will not cool a
car. We are replacing a '64 +4 radiator core right now that is a case like
this. With a new engine, clean water jackets, new water pump (agood one),
an electric fan, a ducted radiator, and an orginal bellows thermost that
opens at 158 degrees, the engine runs 190 to 195 degrees on a 65 degree day
at 60 mph. . This is with a just "rodded out" radiator that looks like
new. This car should be running 170 degrees under conditions like these.
We are installing a continuous fin, louvered fin core similar to , but
better than the original to correct the problem. We are using a continous
fin core instead of a Z fin core (the more modern type) because they are
stronger and more resistant to vibration.
I don't know for sure what happens to the older radiators to cause them
to not cool. I suspect that something happens to the soldered connection
between the fins and the tubes that prevents the conduction of heat to the
fins. This doesn't occure to all old radiators, I am still using the
original core in my own car and it cool well enough to race with a 160 hp
plus engine on a 100 degree plus day and not have the water temp go over 210
degrees! But it is a common enough problem that we see it in probably one
out of four +4s that have their original radiator cores. We also see the
same problem in 4/4, and +8s.
As sor the vibration. It is likely to be caused by an out of
balance clutch cover, a worn pilot bushing, which can cause the clutch disc
to run "off center" and thereby be out of balance, a bad "muff coupling"
that connects the extention shaft to the transmission input shaft, or could
even be a cracked crank shaft.
Regards, Greg Solow
----- Original Message -----
From: Scott Barrie <scott.barrie@CIMtegration.com>
To: <morgans@autox.team.net>
Sent: Wednesday, September 08, 1999 3:56 PM
Subject: An ongoing saga.....
> It's the way of the world, I guess. I've finally had some time to spend
> driving and enjoying my car and..... naturally..... it's becoming a series
> of frustrating of problems.
>
> A problem with misfiring was solved (knock on wood) by a new set of plugs
> and richening (sp?) the mixture by a flat on each carb.
>
> The overheating problem continues and I've been looking for an electric
> fan. I did add an overflow bottle to turn it into a closed system. Problem
> is, after driving the car for a few miles (long enough to get it hot) the
> vital fluid spews out of the rad cap under enough pressure that it goes
all
> over the car or the pavement, rather than into the bottle. Any thoughts?
It
> has a 4lb. cap. Could it just be a baffed cap? Should I consider upping
the
> rating? If so, how high should I go? 7lb?
>
> The other problem that has been developing is a nasty vibration. It seems
> to happen at between 2800 and 3000 rpm but not under load. In other words
> it's at its worst when I'm travelling at a steady speed or off the
throttle
> altogether. It's not the typical Morgan front end shake, but rather seems
> to be originating in the power train somewhere. I've replaced motor
mounts
> and generally checked everywhere for a clearance or mounting problem.
Can't
> find anything that could be causing it. Any suggestions as to what it
might
> be or ideas for how to isolate it would be most appreciated.
>
> Thanks
>
> Scott Barrie
> '63 Plus Four
>
>
>
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