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Vapor Lock in a '28?!

Packard Chicago Service Bulletins #15 & #16 dated 5-18-33 and 5-23-33 discuss drilling a #60 hole in the top of the outer vacuum tank to provide relief to vapor lock. Does anyone have experience with doing this!!?? If it works I'm surprised that it's not well known.

I'm running a '28 6 cylinder that dies after 5 - 25 minutes running, at which time the in-line fuel filter between the vacuum tank & carb is empty; it refills after a couple minutes. I've dropped and flushed the gas tank, blew out the fuel line, taken the inner vacuum tank apart and cleaned it (surprisingly clean). I then put a clear fuel line on the in side of the vacuum tank and watched it operate correctly. I checked and adjusted the point gaps and timing. If it was something with the carb the filter should not be emptied. I have not tried a match yet, but I've been tempted!

I've attached a copy of the bulletins.

Bob Root
Newark Delaware

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  Packard Vacuum tank tech bulletin.jpg (163.82 KB)

I don't see an attachment, please check or provide a link.

Home away from Home, Instead of an attachment it was added below the text with a yellow - tan background. It doesn't show?

I tried to add the attachment again here.

Thanks for your interest,

Bob

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  Packard Vacuum tank tech bulletin.jpg (163.82 KB)

Ok now I see it on both posts. Not sure what the problem was.

Seems to me this problem could be solved with a vented cap unless I'm misunderstanding where the vacuum occurs.

***TOPIC MOVED TO PREWAR FORUM***

Thanks for the response, but the issue is not a clogged gas cap vent. It has 2 vents; the gas cap and the fuel gauge sending unit assembly (it's not called that, but you know....). I opened the cap up to verify a vent issue.

Are there any rubber lines in the system (I have a '37 and '40 and am not familiar with your model).

Rubber lines that look fine can deteriorate from the inside; separating from the nylon reinforcing web that binds the inner and outer rubber. Under suction or draw, the inner line can suck shut, while the outer line looks fine.

I've had this happen on a half dozen cars over time; all that used ethanol based fuels at some point.

Just a thought.

Thanks for the ideas, the only rubber is at the in line fuel filter. The system is none pressurized, so it can't be getting sucked shut. But, with that said I'm going to take the filter and hoses off, and check to see if by any chance they are swollen shut and replace them any way. I'll admit that they are the only things in the system I have not checked, and when ever I do figure it out, it'll be the last thing I check!! :)

Thanks,

Bob

There should also be a rubber hose from the steel line on the chassis to the pump.

You probably have this info already or they may be in the archive but if not, here are a couple of articles on different S-W vacuum tanks. I have no idea where these pages came from or if Packard even used either model or something different entirely. Perhaps reading thru the troubleshooting or comparing to your tank you might be able to figure out where the service article wanted the hole drilled.

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StewartWarnerVacuumTank2-11-27 copy.pdf Size: 522.71 KB; Hits: 160
StewartVacuumTankModel113-UBooket2039 copy.pdf Size: 928.77 KB; Hits: 197