Hi all, got a boost leak on the Fab, all the hoses are clamped up tight however on Boost there’s a loud sort of whooshing sound, much more apparent when the windows are closed! The MAP sensor hole on the Boost pipe is far larger than the MAP sensor itself, would this cause the issue? I’ll attach a video but not sure if you can hear it, easiest way to describe it is like pulling the bung out of an air bed and the air whooshes out

 

Edited 31 January, 20188 yr by JaamesVRS

How is the MAP sensor fitted if the hole for it is too big?

Just like this 

I would definitely use some RTV if you have no gasket, that tiny O ring is doing nothing and you should remove it so it doesn't come off and get ingested.

Edited 31 January, 20188 yr by sepulchrave

Sorry what is RTV? That’s not my photo however it’s similar issue 

RTV silicon sealant, you must make it airtight.

Okay mate thanks, I have Hylomar Blue I’m guessing that’s no good? 

Just now, JaamesVRS said:

Okay mate thanks, I have Hylomar Blue I’m guessing that’s no good? 

 

Not ideal because the MAP sensor is plastic and hylomar is solvent based.

Ahhh okay won’t be using that then! Did you see the video? My Boost gauge is still sitting around the 25psi mark so it isn’t a huge boost leak is it not? Used to be around the 27psi area before hand, I haven’t had chance to get to a long open road yet to see what it settles at or drops at? Possibly the sound makes it sound worse than it is car still pulls well! Just not as well 

Edited 31 January, 20188 yr by JaamesVRS

24 minutes ago, JaamesVRS said:

Ahhh okay won’t be using that then! Did you see the video? My Boost gauge is still sitting around the 25psi mark so it isn’t a huge boost leak is it not? Used to be around the 27psi area before hand, I haven’t had chance to get to a long open road yet to see what it settles at or drops at? Possibly the sound makes it sound worse than it is car still pulls well! Just not as well 

 

I didn't watch it, not really a 'visual' learner I'm afraId although I liked your usage of metaphorical onomatopoeia, very effective.

 

A higher pitched hiss denotes a smaller leak which is probably why the car still pulls well, the turbo can keep up with the pressure loss.

Another question if I build myself s Boost Leak tester am I able to connect it up to where the flexi hose from the air filter attaches to the alloy TIP? Instead of faffing around down the turbo end can I connect it up top and pressurise that way? 

Yes, absolutely.

Just now, sepulchrave said:

 

I didn't watch it, not really a 'visual' learner I'm afraId although I liked your usage of metaphorical onomatopoeia, very effective.

 

A higher pitched hiss denotes a smaller leak which is probably why the car still pulls well, the turbo can keep up with the pressure loss.

It isn’t high pitched like an old school hob kettle whistle it’s more of a whoosh sound, like I said like an air bed, or a Lilo when your deflating that, wouldn’t say it was high pitched like a kettle or balloon 

1 minute ago, sepulchrave said:

Yes, absolutely.

In that case do you know what size that is? I’m hoping 57mm as I have a few silicone 57mm pieces laying around lol 

 

1 minute ago, JaamesVRS said:

In that case do you know what size that is? I’m hoping 57mm as I have a few silicone 57mm pieces laying around lol 

 

 

I have some digital calipers right here...

See I don’t lol and the car is at the lock up, not at home. Brought the van home sadly can’t drive two at once :( 

3 minutes ago, JaamesVRS said:

See I don’t lol and the car is at the lock up, not at home. Brought the van home sadly can’t drive two at once :( 

 

Heyho, no time like the present but there's always tomorrow.

That is true! Frustrating though!! Boost leaks are are PITA! Especially when you don’t have use to a tester or smoke test machine! 

Woo boo, Boost Leak fixed, the boost pipes come with a MAP sensor attached I didn’t know if it was 4 bar sensor or whatever so put my sensor in place to make sure, not realising that it had a reducer plate attached to it so it takes up the 18mm hole in the Boost pipe reducing it to 12mm, Boost Leak seems to be gone! However we’re only holding 25ish psi according to my gauge so possibly got a small boost leak somewhere else or the VNT isn’t set up properly! Need to find out which if I find someone with VCDS lol

54 minutes ago, JaamesVRS said:

Woo boo, Boost Leak fixed, the boost pipes come with a MAP sensor attached I didn’t know if it was 4 bar sensor or whatever so put my sensor in place to make sure, not realising that it had a reducer plate attached to it so it takes up the 18mm hole in the Boost pipe reducing it to 12mm, Boost Leak seems to be gone! However we’re only holding 25ish psi according to my gauge so possibly got a small boost leak somewhere else or the VNT isn’t set up properly! Need to find out which if I find someone with VCDS lol

 

What gauge?

A blue one  Can’t remember what gauge it is, but before the turbo was rebuilt was reading around the 27-30psi mark, now it’s sitting on or just below 25psi 

31 minutes ago, JaamesVRS said:

A blue one  Can’t remember what gauge it is, but before the turbo was rebuilt was reading around the 27-30psi mark, now it’s sitting on or just below 25psi 

 

Clearances may be little tighter on the new CHRA, your old one had bushes like a wizards sleeve remember.

1 hour ago, sepulchrave said:

 

Clearances may be little tighter on the new CHRA, your old one had bushes like a wizards sleeve remember.

yeah that’s true, but why would that create less boost? If anything should be more boost 

27 minutes ago, JaamesVRS said:

yeah that’s true, but why would that create less boost? If anything should be more boost 

 

Well the gauge isn't really to be trusted but it's possible that your actuator rod is not set up exactly the same as before.

what clutch are you running pal?