Hi John,
The TR4 coolant overflow bottle you bought is simply an overflow catch tank.
That's all that were ever fitted to TR4s. You can mount it just about anywhere
because the coolant won't be sucked back into the radiator. It's a one way
trip.
Overflow bottles help keep the car from dripping coolant directly on the
ground (some refer to this as peeing in the driveway), except in extreme
situations where the system is overfilled or overheated. There are also
"universal"
overflow tanks in various shapes and sizes available from most auto parts
stores
for about $20. One hose goes from your radiator overflow to the bottom of the
overflow tank. The outlet and hose coming from the top of the overflow tank
just allows the tank to overflow onto the ground, if necessary, and lets air
out. You can recognize most overflow tanks by the fact that they have snap on
or
non-pressurized screw on caps. With this sort of tank you continue to fill,
check and maintain the system at the radiator.
It's pretty common to confuse overflow tanks with true "header" tanks such as
are used on modern cars. Header tanks have their own pressure caps, sometimes
completely replacing the filler cap of the radiator (which is sealed or
semi-sealed), and these tanks must be mounted high, so that air space in them
is
above the top of the radiator/engine cooling jacket. The radiator, in turn, is
designed without an internal header tank and should not have any airspace when
properly filled. When retrofitting a header tank to an older car, the original
radiator pressure cap is usually transferred to the header tank, and a
special semi-sealing cap is fitted to the radiator, usually with instructions
printed on it directing you to fill the system at the header tank, not at the
radiator. There is also a coolant return line that means adding some sort of
fitting
to the radiator.
The good news is that your radiator actually has a built-in header tank: the
long neck. Notice that the fluid usually equalizes to the same point, with a
bit of airspace. The later "neckless" TR4/4A (and beyond) rads also have a
built-in header, but to me it seems not to work as well, is a little low
considering the water jacket in the engine, and so is slightly more likely to
induce
some air back into the engine, that might cause heating problems. So, the
neckless TR radiators benefits more from installing a true header tank. The
earlier
"necked" rads will work fine with an overflow catch tank, just continue to
keep an eye on the level of coolant in the radiator and pour any coolant the
overflow tank catches back into the radiator every so often.
Alan Myers
San Jose, Calif.
AMfoto1@aol.com
http://hometown.aol.com/amfoto1/amfoto1.htm
I bought a TRF TR4 coolant overflow bottle, and I am planning to
install it immediately the right (passenger side) of the radiator,
attaching the bracket to the inner wheel well. I have test fitted it
& it fits nicely. My question is how much will it matter how high
or low (relative to the filler neck) I mount it? It would seem that
I should put it as high as possible to make the suck back in easier,
but does it really matter practically, given the short range of
possibilities??
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