Rick,
Mssr. Laifman is undoubtedly the alpha to omega on this subject and also
probably the one best qualified to write a standard reference FAQ on the
subject of Tiger cooling. However, there are some differences of opinion on
this subject, so input from different sources may be helpful (or
confusing). There are those who claim, even here in warm, sunny, So. Calif.
that the original Tiger did not have a heating problem. The experience of
many others is very much to the contrary. In many instances the problem was
made worse by making various modifications that were counterproductive
(e.g., replacing the original fan with one such as yours).
I suspect Herr Laifman has suggested that a bigger fan is the most likely
remedy to your problem, although the brown colour of your coolant indicates
some corrosion (rust?) going on that may require a few more flushings
and/or rust inhibitor. But, you may want to take a more thorough approach
to analysing the problem. Your observation that the cooling is adequate
above 50 mph and gets progressively worse below that suggests two
possibilities; a) either not enough air flowing past the radiator or b) not
enough coolant flowing through the radiator. If it is the former, the
temperature at the inlet and outlet of the radiator will be nearly equal.
If it is the latter, the temperature at the outlet will be much lower than
at the inlet. You may also have variations in temperature from top to
bottom across the radiator indicating uneven water flow. If you have access
to an appropriate temperature measurement instrument and can map the
temperature profile of the radiator, this would be very informative as to
the cause of the problem.
Note that of the two possibilities mentioned, having essentially the same
temperature at the inlet and outlet is also consistent with having a very
good cooling system; i.e., coolant flow through the radiator should never
be the limiting parameter. This point is gotten backwards by many who jump
to the intuitive assumption that the better the system is working, the
bigger the temperature drop in the coolant across the radiator when, in
fact, the ideal case would be approaching no temperature drop across the
radiator. This ideal condition is closely approximated by having a good
water pump that pumps more than sufficiently at all engine speeds. I have
known of cases where a brand new water pump does not pump well enough at
idle and a problem such as you describe was cured by replacing the pump. I
believe from my personal experience and what others have told me that the
best pumps have a cast iron impeller, not the stamped metal ones commonly
found on aftermarket pumps.
You do not state which gear you are in when driving in the 30-40 mph range.
If the engine rpms were about the same as for the 60-70 mph test, then I
believe this would tend to eliminate the water pump as the problem since
the only real difference in this case would be the air velocity past the
radiator.
If your auxiliary electric fan was running for the idle test, then it may
be relatively ineffective as well. If you use a high volume mechanical fan,
then no electric fan will be needed. If, on the other hand, you are trying
to reduce the parasitic losses by using a flex-fan or such, then you will
need a good auxiliary electric fan. I know of a Tiger or two that, like
most new cars, uses no mechanical fan at all and relies entirely on an
electric fan at low speeds and idle.
I hope these thoughts prove helpful and good luck with a (hopefully simple)
solution to your heating problem.
TTFN,
Bob
At 02:03 PM 5/9/99 +0100, Richard F Flynn wrote:
>
>Apologies to bring up what is no doubt a tiresome subject for some (a FAQ
would
>be helpful here - saw the start made in January - would be great to see it all
>come
>together!), but I am trying to cure my recently acquired Tiger of its hot
>temperament.
>I have surfed the list archives heavily, had some helpful advice from Mssr. S.
>Laifman, and would now like to ask the list at large for any comment on my
>proposed
>course of treatment below.
>
>thanks in advance,
>
>rick & B9471206
>
snip, snip, snip, . . . .
Robert L. Palmer
Dept. of AMES, Univ. of Calif., San Diego
rpalmer@ames.ucsd.edu
rpalmer@cts.com
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