911SC smoke test

[Niels911SC]

Do you think my pop-off valve is leaking?



I guess I'll have to pry it loose to reglue. It feels pretty sturdy

[pmax]

Yeah, epoxy

[Niels911SC]

I pried it loose (came out with quite a bang), cleaned and filed down the surfaces a bit and put it back with a generous amount of JB Weld, which seams to have solved the big leak:



Now onto the smaller leaks. A couple are obvious at the injector seals, but there seems to be some smoke coming from the left front where I can't really see. Would that be the cold start valve?

[Niels911SC]

Holy smokes! That was a massive leak! I took a drive after reglueing and it wouldn't even idle anymore after warming up. Just died. Turn the CO back three notches, then connected the CO meter: 6.8%
Turned it back a bit more, adjusted idle and CO to ~3.2%
Idle is smoother but still not as smooth as I would like, so the injector seals/sleeves should probably be replaced next.

[Funracer]

Originally Posted by Niels911SC

then connected the CO meter:.

Sorry for the minor hijack. What CO meter are you using? Thanks

[Niels911SC]

Opus 40B, bought it from a shop that was closing down

[Ginger77]

good job. what kind of smoke tester did you use?

I'm nearing the completion of my CIS rebuild myself and it wouldn't hurt to check for leaks if I experience any anomalies.

[trond]

airbox is made from thermoplastic. Epoxy will not bind to it. As many have observed

[Niels911SC]

@Ginger the smoke machine is an AUTOOL SDT-202 that I ordered from a well-known web retailer (do a search on the name, it's the first hit that comes up). It's a Chinese product but very well made. It's not cheap, but I was still amazed by the quality actually, both of the product, its included attachments and the the packaging.

I'd lend it to you but I live in Sweden (Gothenburg) nowadays and with the current covid restrictions there's no way I'm going to visit The Netherlands any time soon

[OldSpool87]

You can buy a smoke tester off eBay for appx $70. Or head to local hardware store for an unused paint can, tubing, gator clips, mineral oil, etc and home brew one yourself. There are some threads out there on making smoke testers.

[Showdown]

Permabond makes several polyurethane and other adhesives that bond glass reinforced nylon well. The air boxes are nylon with glass reinforcement; there was just a thread here about an air box and it was stamped with the materials code.

Alternatively, ultrasonic welding is the best solution but you need the tools.

[Niels911SC]

Guys, honestly there's only one solution here: buying a new air box and NOT putting in a pop-off valve. I did not want to go that route now and take out the whole CIS and fix all the "while-youre-in-theres", but I will probably do that next winter. So the JB weld is only a temporary quick fix, which seems to have worked relatively well for some forum members.