There is however the usual overkill option - fit a
hideously uprated radiator
Which is not only unnecessary but arguably unwise. Radiator
capacity is NOT the problem, so adding capacity is a waste of time.
And if it makes the rad EASIER to plug up – which IS the problem –
you’ve just made the problem worse. And, worst of all, you might
even THINK you’ve done some good, and therefore don’t react properly
when problems recur.
I’ve lost you there… I am not talking about capacity as such. I am
talking about a cooling capacity. This should be about volumetric
efficiency, not about the amount of water a radiator will store.
Then we’re talking about the same thing.
I do accept your argument about using a rad that plugs up easier,
which would, presumeably, be one with smaller diameter piping. So, the
idea is, it seems, to put in a radiator with thicker piping, and more
Thicker piping is good – but it will REDUCE capacity. At present,
the rad is a 1-1/2 pass (half the coolant makes one pass, half makes
two passes), and the biggest improvement we can make there is to
change it to single pass. This won’t change capacity, and it will
only have a minimal effect on tendency to plug, but it WILL ensure
that both banks run the same temp.
Ideally, I was looking for a reputable product that someone on the
list has tried and uses, which will “just add cooling”…
You’re dealing with a fixed size hole where the radiator goes. If
you can’t install a bigger radiator, then the only way to increase
capacity is to go with smaller tubes, or corrugated tubes, or closer-
spaced fins, or more tubes crammed closer together – all of which
either makes the coolant passages easier to plug up or the air path
easier to plug up. IOW, you’re making our known problems worse, not
You need to know that they’re working
CONTINUOUSLY, not periodically. That’s why we have a temp gauge –
to tell us all is working.
I’m not disputing that, but at the same time, I cannot say that I
trust the temperature gauge on my XJS. This is why I am intending to
fit a '87 style digital dashboard from an XJ40 into it, which has very
clearly marked LCD displays that display the actual temperature.
Which will accomplish exactly what? Either one works fine if you
Speaking of which - where can I get a stupidly uprated radiator
for a V12 XJS (HE) that will fit straight in without the
requirement to “make room for it”? I’m really looking for a
straight bolt-on replacement - just with more cooling ability.
For added convenience
I suppose not having a engine overheat would be convenient.
longer engine life
You won’t get that from a radiator prone to clogging, no matter what
it’s capacity is.
reduced possibility of
dropping valve seats
or any other overheating related problems?
IOW, you apparently have completely failed to understand the CAUSE of
the overheating problems. Hint: it ain’t capacity.
there is a not-too-difficult possibility to have a more adequately
overspecified cooling system, then why not do it?
Because of the negative aspects, such as increased tendency to clog.
In fact, put an aftermarket radiator for the XJ-S on the market with
the following claim: “a 1/16” ball bearing can pass through the
tubes" and you’ll have something. Unfortunately, I think you’d be
hard-pressed to get anything thicker than a fingernail file through
the tubes on this rad, and the “uprated” cores are usually even
worse, sometimes having corrugations on the tubes to increase surface
area, which gives a higher capacity when clean but just encourages
stuff to get lodged in there and makes it nearly impossible to rod
If I understand it correctly, the aluminum radiators use larger tubes
than brass radiators. Dunno why brass radiators don’t use larger
tubes as well, since it’s not THAT much of a factor on the total
capacity. But you CAN use a tiny tube on a brass radiator, while
using larger tubes on aluminum radiators makes the welding easier.
Whatever, it ends up a powerful argument for going to an aluminum
All of this, of course, illustrates why the MOST important thing is
to get coolant filters in those upper radiator hoses. Without them,
all is lost.
-To unsubscribe go to
http://www.jag-lovers.org/cgi-bin/majordomoOn 18 May 2001, at 9:10, Gordan Bobic wrote: