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Re: [TR] 4 vs 6 vane water pump impellor

To: "'John Macartney'" <john.macartney@ukpips.org.uk>, <triumphs@autox.team.net>
Subject: Re: [TR] 4 vs 6 vane water pump impellor
From: "Randall" <TR3driver@ca.rr.com>
Date: Fri, 30 May 2014 09:30:02 -0700
Delivered-to: mharc@autox.team.net
Delivered-to: triumphs@autox.team.net
Thread-index: AQIXNqYlx0Y18LvWsC70CqUVa6kciprJPFLAgACV+fA=
> Oh Fountainhead of such unquestionable knowledge, may I most 
> respectfully
> suggest you do a quick spool-back and exclude the Stag V8? :)

You are quite right, John, I was thinking only of the TR2-6, not the Stag nor 
other Triumphs that I have no experience with
(Spitfire, Herald, etc.).  I should have been more explicit.

> It's 
> bete-noire was
> cooling. Period.

I agree entirely, and yet I still feel that lack of water movement was not it's 
primary issue. Cooling systems, like chains, are
only as strong as their weakest link.  The Stags' biggest cooling problem 
(ignoring things like casting sand left inside the coolant
passages and heads that leak combustion gases into the coolant) appears to be 
lack of air flow through the radiator, combined with
insufficient surface area of the radiator.  The body design has limited area 
for air to flow into the radiator, and a largish open
space underneath the radiator that I believe allows air to "pile up" in the 
space behind the radiator, further blocking air flow.
Some folks have even observed that upgrading the radiator can be 
counter-productive, as the increased fin and tube count further
obstructs the air flow through the radiator.

As I'm sure you know, the Stag underwent several major redesigns of the cooling 
system.  Practically every component was changed at
least once.  And yet, the water pump itself was not changed during those early 
revisions.  They did eventually switch to a 12 vane
pump, but that was much later (after the Stag was no longer imported to the 
US).  The reasons for that change are debatable, but
since there were no other cooling changes at the time, the theory that it was a 
"parts consolidation" effort makes sense to me.

I own an early Stag, with the early cooling system completely stock except for 
a recored radiator.  When it runs hot, the water
coming back from the radiator is still almost as hot as what went in.  If the 
water flow was the limiting factor in cooling, then
the water coming back would be significantly cooler.

So, for TR2-6 and Stag, I still feel that lack of water flow is not the main 
source of cooling problems.  I've not tried running a
12 vane pump on my Stags; but I have tried going from 4 to 6 on my TR3, and it 
made NO detectable difference in cooling.  Once I
found and fixed the real problem, all the cooling problems disappeared like 
magic, even with a 4 vane pump.

YMMV of course.

Randall

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