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Did they add the air flow tube after the war?

In that '41 bulletin, why did they say changing over was not necessary on 18th series 1940 cars? Did they change their minds later when there were reports of rusty valves?

Certainly cars were driven less during the war because of gas rationing, so problems from not driving (storage) would have been more common.

I guess if it starts burning more oil, I can change it back. We can make a little cap for that air flow tube on long freeway trips.

The horizontal tube was continued after the war but I believe some have said it may have been discontinued by the 23rd series 356. I would need to find it in the parts book to confirm where it stopped.

According to one of the bulletins the reason for it was the oil filter. It was found the round shape of the filter canister and location of the fill tube created turbulence and some blocking of the air flow on the 356. The longer fill tube and different cap was made available for all engines but the 356 with the stock filter and confined internal passages was predominately the engine of concern. In addition to blocking some flow the turbulence actually created a low pressure area behind the filter which could cause a sort of vacuum. The horizontal tube was an effort to feed air from the fan directly into the cap and force air thru the internal confined passages.

I haven't checked the parts book but I've never seen the horizontal air draft tube on a original 22nd series 356.

I think that may be very possible. It is on my 47 but they may have found the redesigned and shorter postwar oil filter canisters may have taken care of the blocked air flow and turbulence problems so there was no longer a need for the horizontal tube.

A half-hour ago, son John Facetimed me with the engine running. "Dad, you won't need to put a nickel on it to see how steady it is, you'll need a dime." Very smooth, but a leak on one head stud. The rebuilder torqued it. John checked it, but this is the next issue.

However, it fired up on contact. I'll get some pix and video on Saturday.

What is the SOP if you find a leaky head stud/nut?

Bear in mind this is a completely rebuilt/machined engine, new head gasket, everything torqued to 60 lbs.

Now what?

What kind of leak -- water, compression ??

If water did the studs have sealant applied to the threads going into the head since many locations are directly into the water jacket? Leakage must have been an ongoing issue because postwar they introduced special studs with different threads to better seal water leaks. The studs are not applicable and usable on earlier engines though. If there was sealant applied perhaps time or one of the coolant products for porous castings will take care of it.

If compression then I would wonder about damage to the gasket or a machined surface.

You might try to double-nut the stud and see if it can be tightened. If not, see if it can be removed (after draining coolant of course) and use some good old fashioned gasket shellac on the threads and try again. You might also add one of those GM/AC coolant sealing pills just for good measure.

If it still leaks, time to suspect a head gasket problem. Many of us have run into the occasion when a new headgasket looked OK but upon removal after leakage we saw some damage that went unnoticed previously.

It's water. I'll pass this on to John and get some pix and video tomorrow.
Thanks much.

EDIT: After warming up the engine a bit and letting it cool, John was able to re-torque the head and was able to tighten it down more at 60 lbs. We'll see tomorrow, but he thinks it just needed torquing after being started for the first time.

Also to say this is a postwar '47 356, so it should have the new studs.
John says there isn't enough thread to double nut it. We'll see in the morning. It's supposed to be a nice day. Maybe we can take it out of the barn for a spin, see the difference in steering, brakes, clutch, and sway. Can hardly wait.

The head gasket is good, but the studs are leaking and were not tightened into the block. Central Cylinder Head took responsibility and will cover the oil and the gaskets we'll need to pull the head.

I'm in the process of ordering new studs, washers and (while we're at it) stainless acorn nuts.

And in the process checked the engine number. I'm not sure if there are two places for the engine number, but I remember determining that we had a 1947 356 from something stamped underneath. But from the casting, it turns out we have a 1948. But the numbers weren't cast very well.

So am I reading this casting correctly? G6068180?

Having to redo the head is a shame, because the engine is running so well, but I hope it will help someone else to be sure the threads in the block and, more likely, the studs themselves are good and that they install tight to prevent leaks. The rolled, slightly over sized threads should do the trick. According to Bruce Blevins, Packard didn't use sealant. So with the correct studs #341119 (1940-1950), new washers (3883) and nuts (7007 reg or 141987 acorn), we can eliminate the leaks.

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