[TR] Overheating issue

[Rye Livingston]

I'll check out the tabs to see if they are in good order or not.

As for the cap, the one I was using is 1" deep, and the new one I bought yesterday at British Motorsports is also 1" deep
.
Rye
PH: 530-FIND-RYE

On Jun 20, 2017, at 10:14 PM, Randall <TR3driver at ca.rr.com> wrote:

> If 220 is enough to cause a boil over, I’d think the capture bottle would
> fill up but not unscrew the cap. Then when it cools down it would suck the
> fluid back into the radiator. I think it’s the radiator cap and plan to
> replace it.
 
The cap should definitely not unscrew itself; even when boiling over.  However, the fault may be the radiator neck rather than the cap.  There are two little tabs that the cap is supposed to catch on; the tabs may be worn down or torn up (or even deliberately removed).
 
Any radiator shop should be able to replace the neck for you for not much money, but you'll probably have to remove the radiator and they may have to order the neck.
 
Another possibility is that you have the wrong cap.  The original TR3 radiator takes a special cap that has a longer "reach" between the sealing surface inside the neck, and the top of the neck.  IIRC that distance is 1" on a TR3, 3/4" on the vast majority of cars (including later TR4A).  If you have installed a short reach cap by mistake, there might not be enough force to keep it latched in place.
 
It's best to double-check that distance; as some crazy people (including myself) have had the neck modified to accept a modern short reach cap.
 
My experience has been that the supplied original type caps (with the long reach and 4 psi pressure limit) will not work correctly with a recovery bottle; even if you add a seal between the cap and the outer rim of the radiator neck.  Apparently, they leak air through the center rivet (but I couldn't make one work even after surrounding the rivet with RTV).  What worked for me was to convert to a modern cap designed to be used with a recovery bottle.
 
FWIW, I didn't want to clutter up the engine compartment, so I hid the bottle next to the radiator under the RH horn.  I like it there, but of course I fill through the radiator neck, not through the bottle cap as it's almost impossible to reach.
http://s258.photobucket.com/user/TR3driver/media/TS13571L/DSCF0013-2.jpg.html
 
-- Randall
 
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