Packard Forum Index » Pre-War (1899-1942)

On my '37 120, the manifold heat valve is not stuck, but the thermostatic spring seems to be too weak to operate it. Does anyone know for sure which way is open on the heat valve? I don't need it around here in warm weather. I need to wire it open until I can get a new spring.

37 should be like other years and weight would be down. With engine cold the spring keeps the weight up and valve closed. As the spring warms it reduces tension and gravity pulls the weight down to open the valve.

If spring has been damaged or shortened so you cannot remove the center tang from the valve stem slot and wrap the spring another 1/2 turn and tighten it enough to hold the weight up, believe Max Merritt has new ones.

Here is a bit from a postwar manual which typically covers the adjustment on most of the inline engines. Details on how the spring mounts or direction it winds may vary but the operation and adjustment is about the same for all.

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Thanks for the information. I put WD 40 on the heat valve shaft and after some manual working, it freed up nicely. With the engine at about 100F, the spring can just raise the weight to the up position.

I'm going to leave it alone as long as it opens fully when hot, at least until cold weather.I suspect that on a cold morning, it would hold the heat valve closed firmly.

Not sure how WD-40 will react to heat so you may want to keep an eye on the valve. WD-40 does have some petroleum based solvents but since it is mainly a water displacement and rust preventive product rather than a lube maybe the solvents are no worse than kerosene and not concentrated enough to cause issues. Maybe pick up a graphite based lock lube and give the valve a couple of applications just to be on the safe side.

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Be wary of WD-40, as it can gum things up when it's exposed to that exhaust heat.

I got a NOS spring from Merritt for my '47 356 in the early '90s. Michael Grimes there is a prince, most helpful.

I got John Kepich to make a new stainless steel manifold heat control thermostat spring cover at that time, since the original tin covers typically rust.

Work graphite powder into each end the best you can with some kerosene. The kerosene will burn off, leaving the graphite.

The gents above are right. Don't use WD-40. It's good for many things, but not a universal panacea. It was originally developed for things like IBM storing complex Executive Model B/D typewriters with u n i t spacing. It was the 40th attempt, hence the name. WD-40 is a moisture dispersant, not a lube. However, an old auto/aero mechanic/machinist taught me you can sometimes use WD-40 or an extremely thin oil to "draw in" heavier oil to some bit needing lube.

I have some fine powdered graphite. I can mix it with lighter fluid to help get it into the bearing area. My car '37 car doesn't have a cover over the spring. It probably should have one.

The bean-counters abandoned that cover part later on. Guess it was deemed non-critcal.