I have experienced four other instances where a car ran hotter on the
highway than in the city.
The first is if the radiator is undersized, partially clogged, or has air
pockets. This would make the system unable to cope with the added heat load
of sustained high RPMs.
The second is if an electric fan is fitted but pushing air out the front of
the car. The fix here is to reverse the direction of the fans.
The third is if an oil cooler is fitted in front of the radiator and is
leaking. At high speeds a thin oil film can develop on the radiator and cut
its efficiency.
The fourth is a situational thing. If you are running at highway speeds in
traffic the incoming air will be hotter and more turbulent then when you are
running with clear road ahead. There is nothing you can do here but
increase following distance. My V8 runs about 10 to 20 degrees hotter in
highway traffic, but cools right down if I get about 200 yards, or so, clear
road in front of me.
I would verify all of these things, along with the timing/mixture as Max
suggested, but if they all check out I wouldn't worry about it. The temps
you experience are ok. I don't know how much a problem it is with your
situation, but one issue with putting the V8s into Bs is that you are
putting engine into the path of the exiting air, thereby reducing the
ability of the under hood air to escape from the engine compartment. It
isn't much of a problem usually but can lead to increasing under hood temps
at high speeds.
James Nazarian
71 MGBGT V8
71 MGB Tourer
-----Original Message-----
From: owner-mgs@autox.team.net [mailto:owner-mgs@autox.team.net] On Behalf
Of Max Heim
Sent: Wednesday, June 09, 2004 11:04 PM
To: MG List
Subject: Re: MGA running temp.
on 6/9/04 7:14 PM, Danny Varnado at dannyvarnado@cox.net wrote:
> List, I have a MGA with a 74 MGB engine and radiator.
> Does anyone else have a car w/this setup? What temperature should the car
be
> running at at hiway speeds? Mine is running at about 212F on the hiway
and
> 195 in town.
>
While the actual readings are not that much of a cause for concern (and how
accurate is that gauge, anyway?), the problem is it that runs hotter on the
highway. It should run cooler on the highway due to increased airflow though
the radiator (though I understand airflow through the grill opening is not
an MGA strong point). It makes me wonder if you have a timing issue, or a
lean mixture.
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