Vacuum Leaks?

[AMSRoadRunner]

1986 Porsche 911 3.2

Adjusted valves, new ignition system (even coil) and it is still idling funny.

Made a smoke machine (only took 18 months) and found 0 leaks. (also didn't have the throttle open.)

But, I think I have found the issue. The big vacuum hose that goes to the cruise control actuator is not hooked up to anything. Bently, owners, 101 projects, sticker on car, none of them have the cruise actuator in the schematic. Where does that big hose go?

Thanks you all!!

Andrew

[rwest]

That cruise control hose isn't hooked to vacuum, it is just open to atmosphere.

[AMSRoadRunner]

well, boogers. Back to the smoke machine.

Thanks!

[rwest]

Apparently the large hose that goes to the brake booster can be a big source of leaks.

[Nick Triesch]

With motor warmed up remove the oil cap. If RPM's go down then I bet you don't have a vacuum leak. Maybe something else. You would think a 30 year old car would run better!

[Nick Triesch]

Also, try a bottle of Techron. ........Really. Works wonders fast!

[AMSRoadRunner]

I will try opening the oil cap. See what happens.

Suggestions on where the brake booster hose commonly fails?

I did try some lucas, but at this point, I'll try that too!

[steely]

Originally Posted by AMSRoadRunner

Suggestions on where the brake booster hose commonly fails?

It could happen where the line connects to the rear tunnel:
vacuum leak you probably didn't ever think of

[steely]

you should have this sticker on the underside of your deck lid (minus doodles)
If you are sure loss of vac is your problem, there could be a few locations that need addressing, even check the intake nut torque. Mine kind of benefited from my replacing most of the lines I could reach in the eng bay.
But if this isn't the issue, let us know and good luck.

In this jpg, the question mark should read "not connected" or vent or something.

hth

[AMSRoadRunner]

Rocking this AM.
Oil Cap on, oil cap off. No change.
Plugged the vac line for booster. Does not die as frequently.

I suppose if I was really smart, I would have replaced all the vac lines when I had the motor out. Why? They are 30 years old and perhaps a bit outside their engineered life expectancy?

Here is a bad video I took.
https://youtu.be/ulBtXHJniG0

Before I go throwing parts at this poor thing, any more suggestions?

Andrew

[seanratpel]

Sounds like you might have the (restrictor) bullet like piece. (do search) in the wrong breather hose

[75 911s]

Originally Posted by AMSRoadRunner

Rocking this AM.
Oil Cap on, oil cap off. No change.
Plugged the vac line for booster. Does not die as frequently.

I suppose if I was really smart, I would have replaced all the vac lines when I had the motor out. Why? They are 30 years old and perhaps a bit outside their engineered life expectancy?

Here is a bad video I took.
https://youtu.be/ulBtXHJniG0

Before I go throwing parts at this poor thing, any more suggestions?

Andrew

I hear a noticeable difference between cap on and off.

[CCM911]

Steely has the right idea. Tighten down all the fasteners holding down your intake to the engine. I did mine and it was total bang for the buck.

[AMSRoadRunner]

Looks like that restrictor is where it is supposed to be?

And if I am following drawings correctly it does go into that filler neck?

FOUND SOMETHING!!
The breather hose on the block has a 1" crack in it. Of course I really feel like a schumck as I checked those hoses before reinstalling the motor. Should have taken them off and inspected.
Can I use stock hose for that ? I know they have some special bends and stuff.

Thanks again!!

[steely]

Yes your restrictor is cool.
oil breather hose restrictor - idle issue update

Congrats on finding a leak, but I don't know about your question.
I used generic vac-rated line from pep boys or autozone , but mostly for the smaller diameter lines. I guess you could for larger, but really don't know.

[AMSRoadRunner]

At this point I am going to treat this problem the same way my cousin dealt with his '81 Volvo 242t. All the vacuum hoses, o-rings, etc get replaced. While none are "failed" the cumulative effect is significant.

Most of the hoses are coming from Pelican Parts but a few (namely the one with the restrictor) was updated to a two piece hose, then NLA. So I will keep everyone posted on what I find!

Since intake is coming off (replacing all those gaskets with ones I didn't cut myself) and the gasket between the two intake halves, do I drop the motor, again, or struggle through pulling the intake?

[steely]

Your choice, partial drop or do in place.(just my opinion)
I did this job some years back (with zero experience) w/o doing a partial (I was intimidated), but you may have more success doing a partial since you've been down the road before.
that said, if you need to attack the booster line, a partial may be obligatory.
I agree with your assessment BTW. I did most of my lines and saw a definite improvement.

[rwest]

Partial drop is so easy and gives you extra maneuvering room, I would do that as a minimum. Full drop would really make the work easier.

[AMSRoadRunner]

Update:
Pulled the intake. (once you take off the MAF and blower motor the intake fits out quite nicely.)
Sure enough the hose with the bullet was quite badly cracked. It did come from Pelican they incorrectly labeled it as the hose that goes to the intake.

So at this point I have replaced:
Plugs
Wires
cap
rotor
coil
MAF
Hose between intakes
Large hoses associated with oil tank
vacuum hoses
intake manifold gaskets (all 12)
Speed and position sensors
plugged hose going to cruise control and brake booster
Temp sensor
Flywheel (and clutch kit)

While this may seem like throwing parts at the car... well, it is a little like throwing parts at the car.

Any suggestions?
Thank you all!

[AMSRoadRunner]

Also:
found this in the intake