Where does this go?

[ninelevenick]

Today I regapped all the spark plugs on my '79 SC. After buttoning things up, I discovered a disconnected vacuum hose that comes from the fuel housing next to the air box. Anyone know where it goes?

[euro911sc]

Could be the decel valve. attached on the left small flat cylindrical thing.

Also, you need to make sure that you replace the studs that the air pump was with the correct length so you can put proper nuts on them. This will make sure your chain covers are properly tight.

[ninelevenick]

Holy crap, euro! I never thought about those studs! What I may do is find some spacers that are about one inch in length and insert them onto the studs. Then, I could torque the nuts behind them.

There is already a hose attached to the decel. valve. See picture below.

[tirwin]

Some WURs have a vacuum port. I don't remember which ones on which model year. Paging Tony or Jim Williams.

The only other thing I can think is it is the advance/retard on the distributor but you seem to have only one port on the diaphragm. Maybe it is only 80-83 that has vacuum for both.

You seem to be missing a heat duct from the lower left engine tin? On the bottom side it normally connects to the left heat exchanger.

[ninelevenick]

For the purpose of having more room to look at things, I have the heat duct out of the engine bay.

The WUR on my car has two vacuum ports. One comes from the fuel housing as well, and the other goes to the thermo time switch.

Also, the diaphragm on the distributor has only one port.

I still can't figure out where that mystery hose plugs into.

[timmy2]

Air pump or charcoal canister?
California car with EGR removed?

[The cap'n]

Looking at the pictures, I see the thermotime switch, which is an electrical device, and I see no vacuum connection .......................... What is this thing you call a "fuel housing"? Do you mean the fuel distributor? Or maybe the throttle body?

Here's a picture from out host's site that may help. I found it by Googling "'79 Porsche 911 warmup regulator"




The Cap'n

[ninelevenick]

Hey Cap'n, thanks for catching that. I meant to say thermovacuum switch for the WUR. Also, I guess I mean to say throttle body instead of fuel housing.

Looking at that diagram, I see a tee connection to the thermovacuum switch. Perhaps one end of that tee is disconnected. I'll have to take a look.

I appreciate everyone's input so far!

[timmy2]

My pick is number 8.... air pump diverter valve?
Picture shamelessly taken from Jim's Basement Workshop here:

Home Page

[ninelevenick]

I checked the diverter valve. It has a hose plugged into it. Besides, the one in question could not reach that far.

[gerben1986]

I'm wondering if you have the same issue as I have.
In my case I also have a vacuumline left, but it's stopped with a screw.

How much vacuumhoses come from your throttle body? It should be 3, when you have 4 it looks like your throttle body is newer and is not for this car.

[ninelevenick]

gerben1986, what you have mentioned is interesting because I have been doing some research on 911sc throttle bodies. I think you may be correct about the one on my car not being the original. Perhaps the one on my car is for the later SC's with both the vacuum retard and advance hoses instead of just having the one vacuum retard hose going to the distributor. What's the story about your throttle body, and what year is your car? This thread mentions something about it:

SC running "too damn hot": Mechanics stumped, So am I !

[The cap'n]

Originally Posted by Snipernick

I checked the diverter valve. It has a hose plugged into it. Besides, the one in question could not reach that far.

You checked the diverter valve? It's not in the picture. Also missing are the air pump, the check valve, and all the stuff that goes with it, including the air pump bracket that goes on those studs mentioned earlier in this discussion.

The Cap'n

[ninelevenick]

The diverter valve is located front right near the charcoal canister, right? If so, yes, I did check it, and it already has a hose plugged into it.

Also, you bring up another point. About 10 months ago I dropped the engine to fix an oil leak. In the process I completely removed the smog pump. It has been a while, so I don't remember a check valve that goes with the pump. Is there a vacuum hose that plugs into it?

[The cap'n]

The diverter valve is part of the smog pump package, along with the air injection "tree", the check valve which goes between that part and the hose from the pump, the actual air injector nozzles, some hoses connecting the above-engine components, and an air filter. The parts diagram shows a 750mm long vacuum line going to the diverter valve. BTW, you'll need all that stuff next time you have an emissions test, and it'll have to be functional.

The Cap'n

[gerben1986]

Nick, this is the story of my car: Unknown hose

But I haven't been able to check the number of my throttle body yet...
Summary: engine and distributor is '78, but the CIS componets look like they're from '80.
So there is a hose to the advance/retard on the distributor , which is not on the '78 engine.

[ninelevenick]

Thanks Cap'n. I checked all my smog pump parts, and I found what I believe to be the check valve. Sure enough, there is a vacuum connection inlet. It seems this is where my mystery hose would plug into. If this is the case, I must have not given it much thought while going through the throes of installing the engine back into the car. I guess I'll just plug it and forget about it.

[ninelevenick]

gerben1886, interesting that your car has the same issue as mine. Thanks for link!