boost leak past injector seals

[adam g]

I carried out a boost leak test the other day to try and resolve my excessive lag issue, it highlighted air leaking past 2 of the injectors - 4 & 5 (I assume these are the only 2 on which the inlet valves were open so more might be leaking).

I have purchased new seals but they are still leaking, using a tire pump I can get the pressure in the intake up to about 10psi, when I switch it off the pressure drops to zero in 40 seconds. I had blocked the breather system for the test.

The seals I bought are the larger 15mm OD, I had the option of 14.5 or 15 so bought the biggest.

Im now thinking it could be the inserts but cant imagine they could wear out as they are a stiff material and it isn't as if there are moving parts to cause wear, so unless heat cycling or age can cause distortion??? has anyone else has this issue.

[newsh]

Yes, it's the inserts, the plastic degrades and shrinks. You need to replace them and seal them in with some silicon sealant, do them all while you're about it. Unfortunately they usually fall to bits when you try to unscrew them so it's an inlet manifold off job.

[adam g]

I see, thanks for the info. Are oem parts the only option or can you get upgrades, eg billet metal inserts.

[newsh]

OEM only AFAIK, but they will last another 20 yrs

[UrS4boy]

Injector inserts and seals info

You might want to read this for some hints:

http://forums.quattroworld.com/s4s6/msgs/266127.phtml

I used a sealing paste and yellow gas-fitting teflon tape (no silicone):

[rynaqui]

Can't remember how I did mine but definitely tape and sealant as above

[adam g]

You might want to read this for some hints:

http://forums.quattroworld.com/s4s6/msgs/266127.phtml

I used a sealing paste and yellow gas-fitting teflon tape (no silicone):

Thanks for the tips on manifold removal. I must resist the temptation to try the job with it attached.

I have Ptfe tape and hylomar blue gasket seal. Should this suffice?

[UrS4boy]

Thanks for the tips on manifold removal. I must resist the temptation to try the job with it attached. I have Ptfe tape and hylomar blue gasket seal. Should this suffice?

Yah, forget trying to take the short-cut (not removing the intake manifold first). That is doomed to fail and will just make more work (cleaning the broken plastic bits out of the intake ports) after you finally realize that you have to remove the manifold anyway.

The sealant that I used was a something that is used on split case aircraft (and presumably VW and Porsche) aluminum engines. Supposedly it remains plyable even at operating temps. I chose yellow gas-fitting teflon tape over the white plumbing telfon tape because the yellow one says that it is resistant to hydrocarbons. (It is used in natural gas and propane fitting situations).

[Pirvu Eugen]

Yah, forget trying to take the short-cut (not removing the intake manifold first). That is doomed to fail and will just make more work (cleaning the broken plastic bits out of the intake ports) after you finally realize that you have to remove the manifold anyway.

The sealant that I used was a something that is used on split case aircraft (and presumably VW and Porsche) aluminum engines. Supposedly it remains plyable even at operating temps. I chose yellow gas-fitting teflon tape over the white plumbing telfon tape because the yellow one says that it is resistant to hydrocarbons. (It is used in natural gas and propane fitting situations).

Thank You!
I didint know the difference between the white and yellow tape...

Eugen

[adam g]

I just Googled it, mainly because I bought a 10 roll pack of the white stuff last week. Apparently the yellow is the same material but double the density for the same thickness and hence double strength. So although the white would do, yellow sounds the best choice and considering it's still only a couple of quid a roll I've ordered some.

[BosnianS2]

Are the inserts available from Audi or we have to go to Audi tradition?

[Pirvu Eugen]

034133555 insert. I just ordered 10 pcs
All the best!

[popdemonic]

anyone knows if the injector bung from golf gti 16v fit our cars?
034133555A

[UrS4boy]

anyone knows if the injector bung from golf gti 16v fit our cars? 034133555A

AFAIK, they don't work because the injectors on the 16Vs were a different design, e.g. mechanical not electrical.

[geneandbolly]

prof, do you know who the frustrated american bike rider in the 1985 tour de france was?? give you a clue - he was "huffy" and he wore brancale shoes . ..

(just testing to see if you're any good at pub quizzes too, or whether it's strictly an audi thing with you . . and no cheating and looking up google!)