I just learned something that may explain some of the overheating
problems on TR2/3 (maybe early 4). The radiator cap listed by most auto
stores as correct for the TR2/3/4 doesn't fit right ! I found the same
problem at three different stores, which all had different brand name
caps (although one said the caps were actually made by Stant).
The problem is very obvious, once you know to look for it. It's about
1" from the inner seat to the top of the neck on a stock TR2/3
radiator. However, if you measure from the lower sealing surface to the
inside of the cap on the listed cap, it is only about 3/4" !
Another discrepancy : the cap listed in the catalog is a 7 psi cap, but
the correct cap is 4 psi.
Anyway, the result of using the cap listed in the catalog is that it
doesn't seal the radiator, but lets water out the overflow, resulting in
I belive the correct Stant part number is 11208, which is listed for
"TR4 with special head", but I won't know for sure until the one I
ordered shows up.
As an emergency workaround, I bought a Stant 11328 (which is the
'Lev-R-Vent' version of the incorrectly listed cap), pressed the pin out
of the lever, and assembled everything but the lever into the neck of my
radiator. Removing the pin gives it the extra travel needed, and the
increased distance on the spring lowers the pressure to about 4 psi
(measured). The downside is that my radiator cap is now one of those
'gag' springs. If you unscrew the cap without holding it firmly, the
spring will launch the top part of the cap into the air <g> Also,
unscrewing the cap to the first click does not fully relieve the
59 TR3A "daily driver wanna be"