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Crankcase Ventilation

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Atrus

Atrus

Jedi Warrior
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I wanted to confirm with you all – is the only place for crankcase ventilation on a stock ‘68 1275 the canister on the timing cover? As was discussed in a different thread, I had a decent oil leak last year. It seemed to be coming from the front of the engine (aside from the standard couple of drips from the rear main) and it’s fairly decent, only after being run for a few mins. Someone mentioned to make sure the crankcase is properly vented.

So, right now, there is nothing whatsoever connected to that canister. I have a Haynes manual, and didn’t see much mentioned. Looking at it and online at Moss, it seems there’s a valve that connects this to the intake manifold (Dual SU’s). I did notice on Baz’s post in another thread, however, that rubber line was run up to a “Y” and onto each carb on his engine.

Is there anything I’d need to do to clear out that little canister? What is in there? My thinking is that the crankcase should be vented with that thing being wide open…unless that’s a valve in itself and it needs vacuum? I’m not sure how this works.

Additionally, does anyone know where this “Y” can be purchased? Is this just a standard Autozone-type item? What size is the line that fits over the port on that timing cover canister? Are there any other vent locations I need to be cognizant of?

Pic (Baz, hope you don't mind. If you want me to remove the link, please let me know).

538b656c37b4435f50a9e4d09b2ca9b70_large.jpg
 
I think the '65 should have a PCV valve on the intake manifold.
Do your carbs have the diagonal ports like Baz's?
 
I have a '68 with HS2's, and yes, they have the diagonal ports like Baz's. Currently, I had just run a piece of hose between the two.

Seems to me, from what I have seen, I should have a PCV. I'd rather do a more clean-looking, cheap setup such as Baz's if it'll accomplish what I need it to. I don't really know what that "canister" is, what's in it, or what I need to do to properly vent.
 
PCV was introduced in California in either 1962 or 1964, I can't remember which, but in the other 49 states in 1968. That car had PCV originally and it was probably in the form of the two diagonal carb pipes connected to a Y and from there to the canister, as in the picture above. The valve cover breather most probably went to the air filter or another smaller air filter. The idea is that air was sucked in by the carbs, coming from the crankcase, and there from the valve cover. This all provides a slight underpressure in the crankcase. If the rings are good enough you can remove the oil filler cap and using a piece of paper, feel a slight suction into the engine.
 
Thanks for the reply - I thought I noticed a valve cover breather in the pic. Interestingly enough, I don't seem to have this. I assume my valve cover was replaced at some point.

I'll try obtaining a "Y" like Baz's and running it that way.

What's in that canister on the timing cover? Anything I should clean out or ensure it's not blocked? Car sat for 10 years before I got it, and it's been 5 years since I obtained it. So, for 15 years min that canister has just been sitting "open".
 
Kevin,
I've been wondering about the canister also. I was thinking of cleaning it out, and maybe putting one of those little K&N breather filters on top of it.
 
The canister, I think contains wire mesh. just for filtering. Clean it in solvent.


the valve covers with the breather came in two types. The old pre PCV cars had open pipes (pic 1). the later PCV types had a restrictor, very small hole in the end. Later they went away from this and used the Gulp valve (pic 2&3)
 
Is it just me or are the pictures unavailable?
 
Bruce, no pics for me either.

OK, another canister question - does this thing come off to clean it out then, or how would I do that? I definitely don't want to pull the timing cover!
 
Kevin, it's part of the timing cover. It is actually an oil separator in addition to a breather. The oil collects on the wire mesh and drains back into the cover while the fumes are vented to the intake manifold. Earlier cars had a PCV valve on the manifold, and the hose ran into that. Later cars used the Y connector at the carbs.
If you should install a vented valve cover, just run the hose to a catch can. You can put one of those zoomie K&N filters on top of that! /bcforum/images/%%GRAEMLIN_URL%%/grin.gif
Jeff
 
Thanks Jeff....so, if you were in my shoes, should I just consider it good enough and run the line, or should I attempt to clean it somehow?
 
I ran a 5/8 hose from the separator to a 5/8 pipe that slides very tightly into the K&N filter. I currently have it tied to the lower radiator hose. (Don't know if I really like the mounting?) I will probably reroute the filter someday.
 

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Kevin, I have never seen one get seriously plugged. If you disconnect it with the engine running, do you feel a slight pressure at the end? Does the idle change when you disconnect it? If the answer to both is YES, don't worry about it.
But, the A series engine liks lots of breathing, so a vented valve cover into a catch can may not be a bad idea.
Jeff
 
Jeff, can't really say as it's never been connected /bcforum/images/%%GRAEMLIN_URL%%/wink.gif Sounds like I need to get my dizzy in order and the intake manifold back on so I can fire it up to check it out.
 
Like Jeff, I've never seen the breathers plugged. However, I have some friends who have picked out the old metal gauze that's in the canister and replaced it with a stainless steel "Chore Boy" scouring pad.

On the Mini engine of the same period as your 1275, the Smiths PCV valve was mounted on a riser off of (and plumbed into) the intake manifold. The breather was plumbed into the side of the PCV valve. As mentioned above, I believe the "Y" pipes came later.

Don't forget that if you run the PCV valve you also need to run a vented cap on the valve cover. The gauze in those does tend to goo-up over time so you should periodically replace them.

Keep in mind that you can add extra vents if you get creative. However, if your leak is steady and severe, it may be an indication that you're getting a fair amount of blow by and no amount of breathers is likely to keep up.
 
Thanks Doug...my goal is to minimize the leak cheaply so I can drive it this season. In 2008, I plan on a rebuild, so it'll hopefully be sorted out then.
 
Kevin,
Over the winter I actually bought a filter for that hose from the oil separator, and put vacuum caps over the diagonal ports on the carbs.
As Jeff said, the idle speed changed and it ran a little rougher, I adjusted, but it didn't run as well as when it was connected to the Y-piece.
Bear in mind that was at idle, and I don't know what it would be like at revs, it just seemed happier connected as the pic shows.
 
thanks for the info Barry, I'll give it a shot. Where did you get the "y" piece, just a standard auto store?
 
Someone probably has one in their scrap heap.
 
Atrus said:
Where did you get the "y" piece, just a standard auto store?
Click to expand...
It was on it when I got it, as Trevor said, there's one or two lying around somewhere if a parts store doesn't have one on the shelf.
 
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