Smoke detectors for dummies

[mike sampsel]

Originally Posted by Coastr

Keep it simple stupid

You certainly made your reply simple.

[scarceller]

Smoke should not be passing by the injector o-rings. If it is the o-rings are cracked or the bore in the runner is pitted or very dirty. Pull an injector that has smoke coming from it and inspect the o-ring and the bore.

[mike sampsel]

Originally Posted by scarceller

Smoke should not be passing by the injector o-rings. If it is the o-rings are cracked or the bore in the runner is pitted or very dirty. Pull an injector that has smoke coming from it and inspect the o-ring and the bore.

Interesting, o-rings are new (this past 6 months), I was thinking the rings seal in the other direction, with vacuum, so maybe a little smoke is okay? But this might mean I need to replace the bore, I'll inspect the bore for cleanliness.

Thanks

Just went and cleaned the bore of the injector with a swab, it must have gotten some crud of the old injectors as I inserted same.
Will be doing this task with more gusto when the engine is removed.

[scarceller]

Small amount of smoke at the injector will likely not matter but I'd inspect the seals anyway. Do all 6 injectors show smoke?

Originally Posted by mike sampsel

Interesting, o-rings are new (this past 6 months), I was thinking the rings seal in the other direction, with vacuum, so maybe a little smoke is okay? But this might mean I need to replace the bore, I'll inspect the bore for cleanliness.

Thanks

[mike sampsel]

Originally Posted by scarceller

Small amount of smoke at the injector will likely not matter but I'd inspect the seals anyway. Do all 6 injectors show smoke?

No just number 5 (partially because it’s injector line was around number fours, fixed that still a few puffs of smoke there). Thinking the air box might have a wee leak too. Difficult to tell in SITU where the smoke coming from under the air box originated.

[OldSpool87]

Originally Posted by mike sampsel

No just number 5 (partially because it’s injector line was around number fours, fixed that still a few puffs of smoke there). Thinking the air box might have a wee leak too. Difficult to tell in SITU where the smoke coming from under the air box originated.

A pen light might be helpful here at least it was for me. The beam of light will, at certain angles, make the smoke more readily detectable.

[scarceller]

Leaks under the airbox could be from the rubber couplers on the intake runners?

Originally Posted by mike sampsel

No just number 5 (partially because it’s injector line was around number fours, fixed that still a few puffs of smoke there). Thinking the air box might have a wee leak too. Difficult to tell in SITU where the smoke coming from under the air box originated.

[mike sampsel]

Originally Posted by scarceller

Leaks under the airbox could be from the rubber couplers on the intake runners?

Maybe, I put on new ones (this past year) and they are pretty tight. Seems unlikely but possible to be sure. I know I heard a crack when I lummoxed in my airbox without finesses ... with engine is SITU. Any way I'll be checking them twice, this time with the engine out!

[gazzerr]

I found new injector o-rings would pop out if the injector hard lines (assuming you have hard lines) are not positioned in such a way that they don't pull on the injectors. I struggled with my number 6 o-ring popping out until I got this right.

[mike sampsel]

Lots of great stuff here, my original reason for the smoke generator was to find vacuum leaks. Doing so, because my removal of my oil cap did not cause a drop in rpm, however, the closing of the idle screw on the throttle body caused the car to die (so the leak not terrible perhaps).

Also, there is an annoying, too far, drop in rpm when decelerating rapidly (clutch in) causing the car to at times stall (unless the idle is just right ... baby bears ). Thought this might be related to a vacuum leak.

Well today when I pulled the air meter lever down the rpm increased. And when I held the lever down and then took off the oil cap the rpm decreased (at least based on audio). So it seems perhaps my vacuum leaks are a non issue and my problem might be corrected by leaning the mixture a tad.

I'll now wait for someone to tell me, I'm full of it! But I don't care this research is fun!
Still plan to check the air-box when I drop the engine.

[boyt911sc]

Mike,

Now that the motor is out and sitting on an engine stand, this is now a good time to do a total evaluation of your CIS components including the air box. Perform an immersion test for your airbox. The owner of this airbox believed he had a good unit and never realized it was cracked until I did the immersion test last week.






The good news is that new replacement CIS airbox is available for a little over $200 and expected to arrive tomorrow according to the shipping information from our host.
This ‘83 SC was behaving very similar like your motor. BTW, the car was serviced and tuned by a local Indy Porsche shop.

Tony

[mike sampsel]

Originally Posted by boyt911sc

Mike,

Now that the motor is out and sitting on an engine stand, this is now a good time to do a total evaluation of your CIS components including the air box. Perform an immersion test for your airbox. The owner of this airbox believed he had a good unit and never realized it was cracked until I did the immersion test last week.


The good news is that new replacement CIS airbox is available for a little over $200 and expected to arrive tomorrow according to the shipping information from our host.
This ‘83 SC was behaving very similar like your motor. BTW, the car was serviced and tuned by a local Indy Porsche shop.

Tony

Yes sir Tony. thank you for the knowledge,

When the engine is out (in about one month or so) I will likely perform one of two things or maybe both:

1.) Perform a smoke/leak test on the airbox with the intakes plugged with corks. It seems, if I plug the intake runner hoses and leave the throttle body etc on the box, then I can run smoke through a vacuum line to the glove covered throttle body and see if/where the airbox leaks?

2.) Send the airbox off for "water boarding"

My fear of removing the intake runners from their current position might stop me from airbox removal.
I recall the joy of installation the last time (in SITU though).

[OldSpool87]

I set my test up with a garbage bag wrapped around the air filter and then strapped the air filter back on. There’s an unused port on the passenger side of my air box that I have plugged with a rubber plug. It enters where air coming from the filter would. This is where I introduced smoke. My test revealed a leak which I could see and feel in the big intake boot on top (Pope’s hat). Fortunately, I bought a good used one from Tony last year and will replace. I have to assume this method would reveal other leaks as it replicates air flow as it would normally occur through the air box.

[manbridge 74]

Keep in mind that under running conditions the injector is sucked down causing it to seal better, I like to test while idling with spray. However, new seals and injector bases are never a bad idea on these older systems.....

[ClickClickBoom]

https://sfbay.craigslist.org/eby/tls/d/oakland-leak-master-the-smoke-machine/6849783440.html