1979 Excella 24' MoHo question re: Mystery hose.

[roadking67]

It's a 2 part question. What is the oil jar collection system in the picture? It looks like some aftermarket kit. Yes that's a real jelly jar, but the lid is factory molded plastic with fittings for the hoses that attach to the lid. Air blows in and deposits oil in the jar. I just emptied it as it was full.

The hose in the Pic a Pop bottle, what does it do? It runs up into the firewall up behind the dash area where the heater system is. A mechanic suggested it might be a vacuum line that controls the heater distribution system. When the engine is running at temp foul oil vapours escape from the brass fitting visible in the picture. The heating system runs cold when the engine is hot.
I found it disconnected just hanging there. I don't know where it's supposed to go.
Perhaps something was removed from the front of the engine area?
It's a 1979 P30 chassis with a 454.

[Magnet18]

Wow, did this thing happen to be a mobile moonshine factory when you found it?

Jokes aside, the jelly jar looks like a PCV catchment system. Filter oil out before sucking it back into the intake.

The soda bottle, no idea. My 83 heat system is not vacuum controlled.

The heat, make sure the heater core isn't bypassed

[kidjedi]

My 1974 definitely has vacuum controlled vent controls (I just replaced all the lines). However, the valve that controls the coolant to the heater core is mechanical, operated by a cable-in-sheath like the throttle line. The warm/cool slider on the hvac controller opens and closes the valve to allow coolant into the heater radiator.


The previous owner actually added another coolant and return line to an auxiliary heater in the back. It's controlled by a manual valve under the doghouse, but I'm hoping to purchase a valve that I can control with a remote switch so I don't have to open the dog house to turn it on and off.


The biggest mystery with my vac system was the coffee can (vac reservoir), but since yours fills up with oil, a PCV catch-can sounds correct. The bottle, however, is a conundrum. Is the "lid" sealed?

[kidjedi]

If "foul vapors" are coming from that pop bottle line, it's probably part of the emissions circulation system like the Ball jar PCV. All that stuff (egr, etc) was removed from mine by the previous owner, but there is a lot of information on the web regarding those emissions systems for our 454 p30's.

[bibbs]

It looks like the valve for the heater is in the lower left corner of your picture. And it looks closed. Is the mystery pipe for your air conditioning?

[roadking67]

Thanks for all of the speedy replies. I concur with the PCV oil catch can theory, and so does my local mechanic.
As to the heater control cable, after lubing and checking, I think that it's in the open, full heat position. That's for the GM factory heating. There is another floor mounted heater under the dash, on the passenger side. It blows cold as well, it has a pull rod type control that is extremely sticky, nearly impossible to move, and moving it changes nothing, so I have no heat from the engine.
So the factory heat on/off control is cable controlled, and blows cold all of the time. What about the air distributor doors? Aren't most of those old Gms vacuum line controlled? My Chevy vans all were like that.

[roadking67]

Moonshine factory? No, but I do brew my own beer. There's still a Mr. Beer keg in there. How do I make sure that the heater core isn't bypassed? That may be the situation.

[kidjedi]

I spent some time with mine today, just tinkering around and rerouting wires, vents, and vacuum lines under the dash. One thing I figured out is that what I though was an auxiliary/additional blower, I'm now thinking might be an additional blower that gets used when the A/C is turned on (a blower that blows across the A/C coils but never the heater core). If I unhook the "auxiliary" fan and just turn on the dash fan, very little air comes through the vents. If I hook up the "auxiliary" fan while the dash fan is on, air comes pumping through the vents like it should. Typing that "out loud" has me thinking... I suppose the other possibility is that one blower is for intake/return and the one I'm calling "auxiliary" is the blower that actually pushes air through the vents. In other words, maybe the factory HVAC utilizes two blowers, one in and one out? That would make sense considering what I'm experiencing.

Additional info.: there were three wires from the "auxiliary" blower hooked up to a three way switch that was obviously installed by the previous owner (weird location and obviously an aftermarket switch). One wire is for low, one is for med., and one is for high. If my new theory is correct, I'm betting at some point those were hooked up to the factory controls to automatically follow the low, med., high on the dash controls, as it changes the speed of what I'm now calling the "intake" blower.

I also found a light blue wire from the dash HVAC controller that is not hooked up to anything. It is only hot when the dash fan controls are on. Thus, I could use that wire to supply 12v to the vent blower and it would only come on when I turn on the dash fan, however, I would still have to use a three way switch to control the output level of the vent blower (low, med, high).

I suppose I could also "do the right thing" at this point, and dig into the dash controls to see what's really going on with the dash fan control and what should happen with the two different blowers.

I just thought of something else... I think I saw a distribution block under the dash somewhere that both blowers are hooked up to. Somebody probably messed with that to add that weird manual vent blower switch, and I'm thinking if I return all the wiring for that block to how it should be, the dash fan control will probably switch both blowers to the same speed at the same time.

It's a mystery as to why anyone changed it in the first place!

[kidjedi]

Forgot to post what I was originally going to reply with!

You might try bypassing that coolant line valve that has the cable to the dash controls just to see if coolant can get to your heater core.

Easier still, have you run the engine for a bit and then felt the hose on both sides of that valve to simply check if coolant is flowing through it (and able to charge the heater core)?

[kidjedi]

Originally Posted by roadking67

What about the air distributor doors? Aren't most of those old Gms vacuum line controlled? My Chevy vans all were like that.

My '75 is definitely vacuum controlled, and you can't change the distribution (hi/lo, floor, defrost, etc.) unless the engine is actually running and creating a vacuum.