Vacuum Lines

[fbfrancis]

I'm new to this group and have a '55 m38a1. For a while now I've been proud of owning a jeep that smell like a lawnmower, but lately I've been noticing that light black smoke consistently comes out of the tailpipe on deceleration, which doesn't go away no matter how lean the carb is tuned. I have the original fuel pump to rebuild, but right now the civy pump's stuck to the side of block. I figure the absence of vacuum pump in the PCV system is robbing the engine of a source of uncarbureted air. So I'm wondering, could I fix this in the meantime by replacing the PCV valve with an empty tube? Or would this just suck good oil out of the block?

I'm looking forward to putting in the vacuum pump so I can hook up the windshield wipers, for the daily showers we get here in phoenix. But in all my reading I can't find any mention or a single picture of a clean air source for the wipers? Are they just suppost to suck unfiltered air? They only hint I've find is in the parts manual, where the wiper diagram shows a truncated tube connected to the inlet, but where would it go? Through the snorkel hole in the hood? There doesn't appear to be any sign of tube having run doen the passenger side. There is a small notch cut into the bracket for the soft-top support bow meant to clear a tube, but I figure they just used the same bracket they made for the m38, which had an air tube there. Right? There's also seems to be no way to conveniently connect the wiper inlets in parellel the way the outlets are.

And why are they connected in parallel? It seems that if one wiper gets stuck up on something, like a chunk of mud on the glass, the other wiper would just clean twice as fast. Whereas if they were connected in series, not only would they wipe at the same rate, but they'd wipe twice as fast. Twice as much air passing through each one, right?

Sorry if this was kind of long, and thanks.

[Ryan_Miller]

FB,

Here is a photo of the wiper line coming out through the dash and you can see the shut off valve. The line should go up the side of the windshield to the wiper motors. The vacuum line coming out of the dash should originate from the intake manifold ( on the earlier M38 is was a brass T of some type), The exhast outlet should go back to the air cleaner.

I am more familiar with the M38 rather than the M38A1. I will dig around and see if I have any more photos of the M38A1 setup.



_________________
Ryan Miller
MVPA # 22010

[fbfrancis]

Thanks for the reply, but that's the line I don't have a problem with. It seems no A1 wipers have clean air coming in the other side. No pictures show it and I have NO idea were the tube would be routed. In the parts manual they even have a diagram of the of the venting system where they show a tee in a vacuum line with a truncated tube heading for the wipers, but no second tee in any cleanair lines.

I'm pretty obsessive about engine wear, so I'm thinking of breaking open a couple of fuel filters and sticking the paper elements over the wiper inlets, which would be ugly but only takes a second to attach or remove. I don't want to drill a hole in the dash, nor do I want an ugly tube running along the outside of the cowl and through the hole in the hood, least not on an A1.

[wesk]

The Army had pretty much given up on the fording thing for the 1/4Tons by 1955. The early M38A1's had the fording system and the army stopped supporting them. They even left them out of the 55 and up manuals. This is all the plumbing you get and they are plumbed parallel.


The two brown hoses attach to the suction (air out) side of the wiper motors.

If you still want to bring clean air to the wiper motors just plumb the wiper motor inlet ports parallel to the aircleaner.
_________________
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php