Boost leak from Inlet manifold injector inserts, advice needed

[RS3 ROCKS]

Hi all. Well to cut a long story short I removed my inlet manifold and had it polished up. I done all the good stuff, replaced the injector port plastic caps that sit in the inlet manifold, and replaced the injector seals as well as a new gasket of course.

The problem I had was that when fitting the plastic caps to the manifold they wouldn't give any indication of when they were tight. They would keep winding down on the thread untill the top hat section would just crack. I ended up cracking 3 out of 4 they are such a bad design. So a trip down to the stealers was needed, to purchase more

I have fitted them all, and sealed them using sump gasket sealer. But I am getting a hissing sound from what sounds like the 4th injector. Has anyone ellse replaced these caps. And if so what did they use to seal them in to stop any leaks?

Audi workshop manaul makes no mention of any sealant to use and it states they are only torqued to 2NM.

Any help would be appreciated. I'm considering getting a garage to test for boost leaks to see if its any of the vacuam pipes underneath the manifold as they are very dirty, have moved them around when the engine was at idle though and there was no drop in rev's so I think I can rule these out.

 

[superkarl]

Find a place that can do a smoke test.

Also, dre_s3 on here recently replaced his, me might be able to give you some tips.


do your injectors have new o-rings??

 

[RS3 ROCKS]

Yeah I'd considered the smoke test. But I've just moved to teh Highlands, and I know finding a garage here with one is gonna be tough. First I have to find civilization lol.

I changed all the O-rings as well. And theirs no noticeable fuel leak.

I leak checked the manifold etc using washing up liquid but didn't get any bubbles coming up.

I've asked Andy as he just made his own manifold. See what answers I get

 

[dusty]

I have my inlet manifold off at the moment because my injectors are leaking, I have purchased new injector o rings and new plastic seats, I have removed the old seats they were very tight to remove the threads on my manifold look like they have loctite on them this is what I was going to use, I won't be assembling till Wednesday so if you find out what audi recommend to use please could you update the thread so as I know what to use thanks

 

[Adam Davis]

Hi mate, i replaced both injector o rings and the plastic inserts a couple of months ago after doing a boost leak test and every injector was leaking :/
I used plumbers ptfe tape and it worked a treat there very brittle and mine didnt seem to have any kind of sealent when removing.

 

[dusty]

Did the new seats screw down ok with ptfe on them? How many times did you go round the seat with the tape thanks

 

[boost-addict]

ptfe tape is hair thick so id say go round twice at least. its also very soft so itll be crushed in the threads as well , which is the idea, but if i were doing it id do it at least twice round, dont forget to pull tight as you wrap it round.

 

[superkarl]

Id have thought any sort of silicone sealant would suffice.

Also make sure your injectors are seated properly in the seats, they should require a tug to remove them.

 

[dusty]

Just had a quick look on eBay and you can also get a ptfe sealant I wonder if that would be any good

 

[RS3 ROCKS]

Thanks to everyone for the comments. The sump sealant I've used should more than suffice as a sealant. So I may try winding them in further when teh manifold is hot, and hope they don't crack.

I think a smoke test is the way forward to see where the leaks coming from.

Dusty theres nothing in the Audi workshop manual stating what to use to seal them, when asking Audi they said they've never had to repace them before. I'd suggest any sealant for high temp areas. Hence why I used sump sealant. Or use PTFE tape as suggested in a post.

 

[Adam Davis]

Oh god i wrapped it a fair few times, i use it for air line fittings all the time at work. Threads in no problems as said above it squashes right down so as long as you dont go mad its fine. Probably 5-6 times.