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There has been much discussion in the past few weeks about the bellow type thermostat that Packard used from 1935-54. Much of it has been on whether it is suitable for pressurized systems or not. The bellows type thermostat was used in many different makes and models of vehicles besides Packard. I have attached two examples of thermostats that we have in stock. One is a NOS Packard and the other is a NORS "Tru Temp" the tru temp has the applications on the side with vehicles up into the 1960's that did run pressurized systems.

The reason for my post is not to state right or wrong when it comes to bellows vs pellet type but to merely point out that a bellow type can be used and will function properly in a Packard's cooling system using a 7 or 13lb cap. I found in one of our aftermarket manufacturers books (Bridgeport thermostats) from 1964 still recommending the bellows type even though the pellet type was already in use.

My point is that if your Packard has a bellows type thermostat currently you should not be alarmed as it will function correctly.
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I bought a NOS bellows type Thermo in a Packard box.I put it in my 48 Custom 8 to replace the one that was in there.It functions OK but I notice the car runs a little hotter than before ie: Temp guage ran at 1/2 now its more like 3/4s.

Thanks for the info. Not being familiar with the construction of these bellows style may I ask if there is any rubber seal or diaphram to deteriorate over time even with NOS never used shelf stock from the sixties?

...is any rubber seal or diaphram to deteriorate over time even with NOS never used shelf stock from the sixties?
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No.

My experience with those old bellows thermostats is similar to GTO. The cars ran hot.

Premium pellet types have demonstrated decades of reliability. When I do replace thermostats I always drill a 1/8 inch bleed hole if they don't have a jiggle valve and on Packards that don't have heater bypass I would drill two with size depending on the unit. This prevents cavitation erosion and promotes even warm up.

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What temp was replacment. Perhaps it was different than what was in your vehicle?

Thanks
James

Same temp as the one I took out-I believe it was 160

T'stats can be tested in a sauce pan full of water on a kitchen stove.

The above discussions about bellows thermostats being affected by pressurized cooling systems is not a recent finding, Packard noted it at the time (1953) that they made the switchover to capsule-style thermostats. The relevant TSB is attached.

Just as an aside, it's interesting to see that alcohol anti-freeze is still mentioned - you would have thought it would be obsolete by then yet I can recall in the 60s having the choice between Zerex (permanent) and Zerone (alcohol).

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