There are a dozen or more possible causes for running hot:
- Rust and scale in either the radiator or engine block water jacket. =
This prevents proper heat transfer. Even a thin layer of scale in the =
radiator reduces its efficiency significantly.
- A bad pump impeller.
- Improper ignition timing.
- Overly lean fuel mixture.
- An improper head gasket, with the wrong water openings.
- A stuck thermostat.
- Missing fan shroud.
- A bad pressure cap on the radiator. Low pressure allows the coolant to =
boil at a lower temperature, drastically reducing heat transfer =
capabilities.
- etc.
By the way, you should ALWAYS use a thermostat in your engine! This has =
several purposes. It helps keep your engine from going through radical =
heating and cooling cycles that can damage the engine. It also keeps oil =
sludge from building up inside the block. An engine that has a working =
thermostat will run longer and cleaner. In addition, removing the =
thermostat won't solve an overheating problem. In fact, it can sometimes =
make it worse because good cooling depends on even water distribution, =
which depends on water being delivered at the correct velocity. Higher =
velocities can sometimes cause swirls and eddy currents that could =
deliver more cooling to some areas and less to others. It may also =
affect radiator efficiency to some degree.
Anti-freeze with rust preventative is a must. In addition to providing =
protection against freezing, it also raises the boiling point of the =
water. It is also more viscous than water, which affects the =
distribution velocity. I'm not sure as to its comparative thermal mass =
and heat transfer characteristics as compared to water, but all in all, =
use antifreeze all year long.
Hope that helps a bit.
Alan
(Salt Lake City, Utah)
-----Original Message-----
From: RKiser8375@aol.com [SMTP:RKiser8375@aol.com]
Sent: Monday, August 04, 1997 10:22 PM
To: mil-veh@skylee.com
Cc: WPace99690@aol.com; 107771.357@compuserve.com
Subject: [MV] M37 Running Hot
My M37 is running hot and getting vapor locking. I live in Denver, and =
the
truck runs at altitudes between 5,000 and 12,000 feet. Also, it is =
fairly
hot here (about 90 degrees Farenheit) and pretty dry (about 20-50% =
humidity).
It seemed as though the radiator was not as hot as the rest of the =
engine.
The engine and everything under the hood gets very hot, but the =
radiator
doesn't get very hot.
=20
I tried adding a gallon of antifreeze. And it was still running hot. =
Then,
we removed the water-pump bypass elbow and turned the fan blade to =
verify
that the water pump impeller was spinning. We also adjusted the idle =
mixture
screw to run a little rich (turned screw clockwise) and retarded the =
timing
some. The last thing we did was switch the manifold valve from Winter =
to
Summer operation, although I don't how much this will affect the =
temperature.
Also, I do not have a thermostat in the engine. I don't believe that =
this
can make it run hot, though, can it?
Does anyone have any suggestion as to what would make the engine run hot
under these conditions?
Thanks in advance for any advice.
Rob Kiser
'52 M37
=3D=3D=3D
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