You are right about the 7 lb cap and brings up an issue I have with the 1961 service manual to which I refer.
On page 118, paragraph H-4, it says: "Early production vehicles were equipped with 7 lb. pressure caps; later vehicles with 9 lb. [0,63 kg-cm 2] caps. Current production Model L6-226 4WD and 4x4 vehicles are equipped with 13 lb. pressure caps; all others with the 9 lb. caps." That's fine except it doesn't make clear what years or serial numbers are included in the categories of "early production," "later production," and "current production."
Since my wagon is a 1960 I'll assume it's not "current production" and is part of "later production," and should be equipped with a 9 lb. cap.
However, I'm using a 16 lb. cap. When the original radiator and heater cores were re-cored, they were pressure tested to 30 psi so I'm not concerned about them failing, nor am I concerned about coolant system hoses, gaskets, etc. The 7 lb. increase in system pressure, with a 33% ethylene glycol mix, increases the boiling point to about 260°F (about 15 degrees more that at 9 lb.) For me, the biggest benefit of a higher boiling point is the prevention of localize boiling at hot spots around the combustion chambers. The lower anti-freeze concentration (from the usual recommend 50:50) is better heat transfer.
If under max power (not there yet) the coolant was to suddenly boil around the combustion chamber, detonation (and engine death) would be he likely outcome.
It would be interesting to know what made your engine "hiss" with the 15 lb. cap. When you say "wasn't cooling right", do you mean overheating?
Walck’s advertisement said fits pick up truck , station wagon models. Mounts like the original... I was just throwing it out there as another option . I was wondering if any forum members had purchased one and were they happy . Im probably going to try to repair mine first and cross my fingers that it lasts . It would be nice to have an exact replacement as an option but I’m afraid to think what that would cost .
