Harm from disconnected PCV?

[David Greenburg]

Several years ago I installed a PCV on my '59; replaced the road draft tube with a hookup into the carb base, using parts from a '63, as has been discussed here.  A couple of years ago, due to a fire caused by a leaky fuel filter, I had pretty much all underhood hoses and wires professionally replaced.  This week, I realized that when this was done, someone removed the fitting that replaced the road draft pipe and blocked it off with what looks like a freeze plug.  Meanwhile, the hose going from the carb to the PCV valve was not connected; it was just lying under the manifold.  Despite the substantial vacuum leak, this created, the car ran ok.  I only became aware of it when I was tracking down an oil leak and realized this hose went nowhere.  But I'm concerned about issues from (1) having the road draft outlet blocked off (perhaps this just pushed the fumes out the oil filler cap instead); and (2) pulling unfiltered underhood air into the engine through the disconnected hose.  I'm not usually a fan of engine flushes on engines this old, but am wondering if something like that or a Seafoam treatment might be indicated here to clean things out and ward off future problems.  Again, I don't seem to have any problems now, especially now that the disconnected hose is plugged.

[The Tassie Devil(le)]

G'day David,

What the Draft Tube, and the PCV does is remove all the "Polluted" air that is floating around in the Crankcase and replacing it with clean air as you are driving along the road, and in the case of the draft tube, whilst you are idling with the car facing into a strong headwind.

What your engine has experienced is stale, polluted, unfiltered air, possibly dust-laden if you were driving in a dust storm or down a dusty road, and this air just sitting there, getting more polluted.

Performing Oil Changes as per Manufacturers' Specifications will have "saved" your motor, but even not doing Oil Changes as often, as us "Mechanics" do, still shouldn't be a problem.

If the PCV Valve was still attached to the hose under the Carby, you probably didn't have much of a Vacuum Leak as the spring-loaded valve in it will let a bit of air through, but not like it was a, open hose.

I would simply be plugging it all back together as you had it with the PCV working.

Don't forget that the full PCV system has the Air Inlet at the Oil Filler Cap totally blocked off, and there is a hose running from inside the Air Cleaner, that is the Filtered Side, and this hose runs into the engine Sump Cavity to allow the Fresh Air to enter.   This is usually done by attaching that hose to the top of the now sealed-up Oil Filler Cap, or one of the Rocker Covers, in the case of an engine that was built without a Draft Tube.

Bruce.

[David Greenburg]

Bruce:

Thanks.  I'm hoping that oil changes are enough.  Fortunately, I wasn't driving on any dirt roads or through dust storms; just suburban California cruising and a few car shows, and probably only a few hundred miles total.  I understand about the the full PCV arrangement, but that is not what I have (or had); the oil filler is vented, not sealed.  The idea was simply to keep the draft tube fumes from stinking up the garage when coming and going; not to try and make it a full-blown emission control system.  But when I discovered the disconnected hose, which had the PCV valve on the end, there was pretty strong suction on the end of the hose; almost what it would feel like with just the an open hose and no valve. 

[TJ Hopland]

What you had sounds correct.  The filler / filler cap does the same job either with the draft tube or valve.  When the valve or draft tube puts vacuum on the crank case the filter / filler cap allows filtered air in to replace what has been drawn out.  In later (emissions years) they did remove the inlet filter from the valve cover and moved it to the air cleaner housing.  Many of the 70's Gm's had that white filter on the outside of the other element while others had the hose on the clean side like others described.  I assume they reason they (feds?) did this was after you got some miles on your engine the pcv system could not take it all but at least that way the carb would still suck it in (along with oil plugging up the carb or air filter making it run richer and with poorer emissions).  Its amazing that cars even ran in the 70's with all the emissions patches on other emissions patches. 

If your carb was tuned to run with the PCV plugging it will make it run a bit richer.  I would put the valve back in and got back to the way you had it.  Besides emissions it keeps the engine internals cleaner.  Some of the performance pioneer race guys used to run a real high vacuum on the crank case, I dont remember the whole theory but they claimed it helped performance. 

[domer]

Can you please post a couple of pics of the PCV valve arrangement and location.  I think I may be in the same boat with my 59.
Thanks

[Dave Shepherd]

Can you please post a couple of pics of the PCV valve arrangement and location.  I think I may be in the same boat with my 59.
Thanks

59 did not have a factory insatalled pcv system.

[David Greenburg]

Dominique:

I don't have much to post a picture of at this point because part of the system was removed (that is my problem).  All you would see at this point if I took a picture at this point (and I can't because it is raining really  hard today) is a rubber vacuum line coming off a nipple on the carb insulator that runs under the intake manifiold back to where the road draft tube should be.  This is something that was added; '59-'60 did not originally have a PCV, even in California.  If you want more information, there is a thread on this  issue (and I think some pictures) a couple of years back.  Try searching PCV conversion.  I think Ed Mobley and Jim Eccleston were among the authors.  I could post a picture once my setup is back in place, but I need the part that replaces the road draft tube (its on order off of e-bay).   

[The Tassie Devil(le)]

This is what I did to convert my engine to run a PCV system.

Bruce.

[The Tassie Devil(le)]

As you can see, I removed the Fuel Pump and also replaced the Oil Filler cap with a sealed unit, of an Oldsmobile 455, top 3" of the Olds part.

The way the hoses run is so that I got completely filtered air into the air intake and not have to worry about sucking the Oil Bath in the original Oil Filler Cap, which someone kindly knocked off while the engine was in transit.

Bruce.

[David Greenburg]

Bruce:

I admire your creativity.  Looks like you have a truly sealed system, like what you would expect to find on a post '63 US car.   I like your rerouting of the fuel line, up high and away from the exhaust manifold, starter cable and other hazards that are near the origianl route of the line.   

[domer]

I was hoping someone could fill me in on what I have going on under the hood. I just noticed it the other night.  Looks like a bolt was used to plug up the line. Purpose??  Correct setup???
Thanks
dominique

[The Tassie Devil(le)]

Doesn't look right to me.

Firstly, the "T" fitting is white Plastic, and from the shape of the cut hose, it looks like someone just sliced the hose in half and inserted a "T" fitting with the hose.

Does the car have a Tow Bar?   Could be a Vacuum source for Vacuum Trailer Brakes?   Or someone attempted to access their PCV Vacuum this way?

The trouble with using a short bolt to plug a hose is that the thread usually goes right to the base of the Head, and allowing a leak through the thread.

Bruce.

[35-709]

Looks to me like someone added a piece of rubber hose to repair an old one or cut out a leak.  In either case they only had a "T" connector rather than a straight through connector so they stuck a piece of hose on it and plugged it with a bolt.  Just my guess.  That "T" is not in any position that you would normally find one in my view.  Where does that hose come from/go to?  If that is a power brake booster vacuum supply hose I would replace it very soon.  It looks suspiciously like someone also fixed another leak where that ancient looking piece of masking tape is.  Don't allow stuff like this --- especially if that IS a power brake vacuum line.
Geoff N.

[domer]

Yes the hose comes off the check valve, into another tee which ties into the brake booster and a round canister below the brake booster.

[Otto Skorzeny]

The round canister is your vacuum reserve tank. This gives you one or two power assisted pumps on the brake in case the engine quits and you need to stop. Buy a new hose and connect it without the T fitting. It should be a single hose without any other crap connected to it.

[domer]

Thanks fellas,
I figured there was something not right about this little setup but wasn't sure about the tee connection. I thought it was some type of required check valve or something.
Thanks very much

[David Greenburg]

Dominique:

Can't tell from the pictures whether your car still has the road draft tube attached.  If so, the fitting would be coming off the engine just below where the bolt stuffed in the t-fitting is.  If you've still got the tube installed then it doesn't look like anyone was trying to install a PCV setup, and supports the theory suggested above, that someone simply didn't have a straight fitting and so installed a T and plugged one end.  I would defintiely replace those hoses.

[Otto Skorzeny]

Let us know if the draft tube setup still exists. If not, I know a guy who posts periodically on this forum and the MCLC who just converted his '59 to a PCV setup during his engine rebuild. He could probably give you some guidance as to type of valve used etc. along with photos. Some are already posted on the MCLC site.

[domer]

Thanks David and Forrest. I am out of town for a number of days but will check it out as soon as I get back.