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Re: overheating, bad, bad, bad...

To: Michael Jose <>,
Subject: Re: overheating, bad, bad, bad...
From: Barney Gaylord <>
Date: Fri, 21 May 1999 10:37:36
At 11:25 PM 5/20/99 -0700, Michael Jose wrote:
>.... My 79 b .... the needle was way over into the red. .... Let it sit in
the shade .... Got down the highway, and the gauge started climbing
again... .... I started to think that the gauge was screwy, .... when the
car started making a clacking noise.  Next, it lost power, and I was unable
to keep speed. .... I checked the coolant overflow, and it was full!
Boiling, but full. .... I *hope* that the problem is the water pump. ....

Yup, definitely overheated.  And when it clatters and looses power while
the water is still in the engine, that sounds like the water is not
circulating.  I had exactly that happen to my MGA once when I installed a
new fan and pulley on the generator, and the new generator fan fouled on a
bolt head of the adjester bracket and stopped the pulley from rotating,
which in turn stopped the belt which stopped the water pump which caused
exactly the symptoms that you describe.  When it happened to me the
temperature gauge stayed pretty close to normal, not much change in
temperature at the thermostat housing even though the area around the
valves was getting WAY hot and causing local boiling.

First check to see that everything on the front of the engine is rotating
when it should be.  Then see if the water pump pulley may be loose and
wobbly, sure sign of a worn out shaft bearing.  Then start the engine, get
it up to normal running temperature, and check to see if water is
circulating in the radiator.  If it circulates properly the top radiator
hose should get quite hot to the touch and the radiator core should get hot
and the air passing through the radiator should be quite warm on the exit
side of the radiator core.

If the water pump pulley turns but the water doesn't circulate, you have
about five possibilities.  1.) Not enough coolant in the system to cover
the water pump impeller.  2.) Deteriorated or missing impeller on the water
pump.  3.) Thermostat stuck shut.  4.) Clogged up water jacket in the
engine block or cylinder head.  5.) Clogged up radiator core. 

If the overheating problem came on rather suddenly, then it's probably not
items 4 or 5.  And since you said the water was "Boiling, but full", then
probably not item 1 either.  My first guess would be a stuck thermostat,
followed closely by a bad water pump.

Good luck, and let us know what you find.

Barney Gaylord
1958 MGA with an attitude

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