# DIY for FSI N75 Valve?



## bkpassat (Jun 18, 2012)

Anyone have a link to a DIY for the N75 valve on a FSI engine? 

Wondering if their is adequate room to maneuver the vacuum hoses, and if they tend to get hard or brittle due to heat from the turbo? If anyone has done the job and needed to replace the vacuum lines, did you get application specific parts from dealer, or did you use generic vacuum line, and if so, what were the sizes?

Thanks..


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## ROH ECHT (Dec 9, 2010)

If you can deal with the oem clamps while turbo is mounted...it can be done. Hoses should not be brittle...but N75 nipples can be. Mine has been accessed as well as replaced while mounted. Look down at the N75 from up top and determine if the wheel arch liner was removed...would that help. Then, for better access and view, I would remove your RH wheel and arch liner and get a look through there. You may want to pick up new clamps...although I've seen them be reused.


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## bkpassat (Jun 18, 2012)

Thanks for the tips. Will be tackling this next weekend. When working on modern cars with tightly packed engine compartments, I like to have any ancillary parts that I'm liable to break in stock just in case. Nothing more frustrating than having all the tools out and the car up and jack stands and not being able to finish the job because of a part that I damaged while getting to the part I needed to replace. I'll report back how it goes. 




ROH ECHT said:


> If you can deal with the oem clamps while turbo is mounted...it can be done. Hoses should not be brittle...but N75 nipples can be. Mine has been accessed as well as replaced while mounted. Look down at the N75 from up top and determine if the wheel arch liner was removed...would that help. Then, for better access and view, I would remove your RH wheel and arch liner and get a look through there. You may want to pick up new clamps...although I've seen them be reused.


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## Thy_Harrowing (Dec 7, 2014)

> Thanks for the tips. Will be tackling this next weekend. When working on modern cars with tightly packed engine compartments, I like to have any ancillary parts that I'm liable to break in stock just in case. Nothing more frustrating than having all the tools out and the car up and jack stands and not being able to finish the job because of a part that I damaged while getting to the part I needed to replace. I'll report back how it goes.


Yes please do report back, I might be replacing mine soon as well. Haven't gotten around to it yet also because of how tight the working space is so I'm not looking forward to it.

I'm curious what sort of issue are you having that has prompted you to replace your N75? I'm curious to see how it compares to an issue I'm having.


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## ROH ECHT (Dec 9, 2010)

You will probably have the best access from up top. You might need to clear away a part or two for extra work room, but if it helps get at those bugger clamps, well. Looking into wheel arch liner removal is to be determined by your inspection and seeing if it will help or not...although my liner was never needed to be removed for access when mine was done. My tech has mo betta tools than I 

Pop in to a VW dealer-shop and ask about removal and install of those [email protected]#!%n clamps beforehand...a special tool may be invaluable. If you don't have helpful VW techs locally...I can pop in and ask mine for you.

I will tell you...if you do a proper DIY thread including step by step instructions, pics, and warnings...you'd be the HERO of the MK5 world! opcorn: ....as many have and will ask for an N75 DIY.


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## bkpassat (Jun 18, 2012)

Thy_Harrowing said:


> I'm curious what sort of issue are you having that has prompted you to replace your N75? I'm curious to see how it compares to an issue I'm having.


Occasional P0299 code and the car seems a tiny bit sluggish at times. Always when fully warmed on hot days. No leaks in air plumbing, replaced DV valve, replaced N80, even replaced PCV. Pretty much only thing left is the N75. All the parts were pretty cheap, but as the N75 seemed like the biggest pain to get to, saved that one for last...


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## Thy_Harrowing (Dec 7, 2014)

bkpassat said:


> Occasional P0299 code and the car seems a tiny bit sluggish at times. Always when fully warmed on hot days. No leaks in air plumbing, replaced DV valve, replaced N80, even replaced PCV. Pretty much only thing left is the N75. All the parts were pretty cheap, but as the N75 seemed like the biggest pain to get to, saved that one for last...



Any out of place noises you've noticed. This is what I've been going through (http://forums.vwvortex.com/showthre...-WOT-only-Seemingly-NO-boost-loss-or-vac-leak!) and N75 is one of my only theories at the moment. No codes, no performance change though, which is what is confounding about the issue.


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## bkpassat (Jun 18, 2012)

Thy_Harrowing said:


> Any out of place noises you've noticed. This is what I've been going through (http://forums.vwvortex.com/showthre...-WOT-only-Seemingly-NO-boost-loss-or-vac-leak!) and N75 is one of my only theories at the moment. No codes, no performance change though, which is what is confounding about the issue.


Read through the thread you linked to. Haven't noticed any odder than usual noises and certainly nothing like what you described.


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## Thy_Harrowing (Dec 7, 2014)

Gotcha. Well thanks for the info. Looking forward to hearing how it goes. I hope it isn't too much of a pain for you (and me). If I actually had any performance loss I'd have done it already and things would be reversed haha. I really don't know how I haven't noticed any performance loss with 4PSI boost missing.


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## bkpassat (Jun 18, 2012)

Read your post and took a quick peek under the hood last night and the top two hoses and the left most screw are easily visible and readily accessible from the top. Looks like pulling the wheel well liner should give fairly direct access to the electrical connector and the lower hose. Felt the two upper hoses and they were still very pliable, so don't think there should be any difficulty removing/replacing the hoses. Recently changed the N80 valve which uses the same crimped connectors. They're actually not much of a problem to remove with a small screwdriver inserted into the crimp to open it up, or just cut/mangle the crimp with a pair of side cutters.




ROH ECHT said:


> You will probably have the best access from up top. You might need to clear away a part or two for extra work room, but if it helps get at those bugger clamps, well. Looking into wheel arch liner removal is to be determined by your inspection and seeing if it will help or not...although my liner was never needed to be removed for access when mine was done. My tech has mo betta tools than I
> 
> Pop in to a VW dealer-shop and ask about removal and install of those [email protected]#!%n clamps beforehand...a special tool may be invaluable. If you don't have helpful VW techs locally...I can pop in and ask mine for you.
> 
> I will tell you...if you do a proper DIY thread including step by step instructions, pics, and warnings...you'd be the HERO of the MK5 world! opcorn: ....as many have and will ask for an N75 DIY.


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## ROH ECHT (Dec 9, 2010)

bkpassat said:


> Read your post and took a quick peek under the hood last night and the top two hoses and the left most screw are easily visible and readily accessible from the top. Looks like pulling the wheel well liner should give fairly direct access to the electrical connector and the lower hose. Felt the two upper hoses and they were still very pliable, so don't think there should be any difficulty removing/replacing the hoses. Recently changed the N80 valve which uses the same crimped connectors. They're actually not much of a problem to remove with a small screwdriver inserted into the crimp to open it up, or just cut/mangle the crimp with a pair of side cutters.


Right, I've dealt with same type only larger....watched my Tech deal with these tiny ones and even reuse them. Might want to have a few new extras just in case.


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## bkpassat (Jun 18, 2012)

ROH ECHT said:


> Right, I've dealt with same type only larger....watched my Tech deal with these tiny ones and even reuse them. Might want to have a few new extras just in case.


I have a handful of these ready to go: https://www.fcpeuro.com/products/hose-clamp-8-12mm-7-5mm-wide - pretty nice quality, incidentally


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## Thy_Harrowing (Dec 7, 2014)

OP did you ever get around to doing this? I'm looking at doing it soon... Wanted to know if you found the job to be pretty easy after removing the wheel liner? Also if you did do it recently I'm wondering if you can recall one other detail... if by some chance one or both of the hoses connecting to the N75 were damaged how easily could the hoses themselves be replaced? Pretty easily or would that turn the job into something much more aggravating?


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## Fogcat (Apr 29, 2015)

I too am interested. When I had some codes that hinted mine was bad, I tried to get at it (in case it needed replacing). I could NOT get to it by removing the arch. There was steel in the way, only from above and below would work. It looks like a real pain....literal as well as metaphorically. In my case it wasn't bad.....yet. Everybody involved in this convo seem motivated and does good methodical work. Please let us know.


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## Thy_Harrowing (Dec 7, 2014)

Well I more than likely will not need to replace the N75 now because I am about 99.9% sure I have found what was causing the issue that I originally thought may have been caused by a failing N75.

However, that being said, until I found that out today I was pretty close to doubling down and not only doing what lead me to find that out but also replacing the N75 too. So while I was eyeing up the N75 job with intake and a few other things out of the way I realized that access to replace the N75 from the top is actually quite a bit better than I first thought. Just from eyeing it up I am pretty sure that I could do like 90% of the job from the top with just my CAI and maybe rear PCV breather hose out of the way (to open up some other angle of attack for N75 hoses). 

I would have done a DIY if I was going to be doing the N75 but since I am 99.9% sure my issue lies elsewhere now I'm probably not going to bother replacing the N75. If after fixing this other thing my N75 duty cycle is still really high though then I might decide to replace it and do a DIY.

In the meantime I'll go over what was going to be my rough plan for doing it while I was eyeing it up:

1) Remove engine cover or CAI, whichever you have
2) N75 is on far left, top side of turbo. There are 2 hoses going into 2 nipples on the N75 and they have 1-time use crimp clamps. Before you go to remove the clamps/hoses, disconnect the thin wiring loom that runs sort of in the way of some of the N75 components. It's the wire loom that runs up towards the coil packs; so you'll disconnect the wire harness unit off the coil packs, then with a small flat blade screw driver you just open up the little plastic connectors that are at certain points of the wire loom as it runs down over the N75 area. With all that disconnected you can pull the loom back and out of the way.
3) Crush the crimp portion of the clamps with a mini vice grips or cut it with small cutters, then pull the clamps apart and off
4) Use a small hose pick to remove the hoses from their respective nipples on the N75. Alternately, if removing the hoses completely proves difficult due to the tight space, pull the hoses back just enough to expose the base of the plastic nipples and cut the nipple itself off, thus detaching the hoses from the N75 body. Then use pliers to pull the nipples out of the end of the hoses which will be a lot easier with the hoses free of the N75 body. Obviously if you do that method you are past the point of no return and must replace the N75 now. Fortunately there's only one tricky part left as far as I can tell...
5) With the hoses off you just need to unbolt the N75 body. I do not know what size the bolts are as I didn't actually remove anything. Off of memory though I think they were hex/allen bolts and judging by size and also experience removing similar bolts during other jobs I suspect they were a #5 hex/allen, maybe a #6. Anyway, whatever size they are, the outter one should be easily accessible with a 1/4 ratchet and stubby hex/allen socket of the appropriate size. The other is the last annoying part of this job and, just from eyeing the job up, probably the most annoying part. It is really hard to even see and probably hard to get at even with the hoses out of the way. I suspect that with a stubby 1/4 ratchet, a short 2 or 3" extension, and the hex/allen socket you can get the angle you need on it if you play around enough. However, I was eyeing up an alternative. I can't attest to this being accurate because I didn't actually do it, but it looked like the entire bracket that the N75 bolts too, which in turn bolts to the turbo, is held on with one bolt (see pic below)... if that is true and there isn't another bolt holding it on that I couldn't see, then one could skip removal of the super tricky N75 bolt and actually just unbolt the bracket itself so that the entire bracket can be removed along with the N75 itself. Whichever approach you choose to take there is only one step left.
6) Lastly, you need to disconnect the N75 connector. If you can do this from the top then great, then you did the entire job from the top if you went by my methods above and they all worked out. If you can't then put the car in the air and then taking a flat blade screw driver to push on the connectors clip in the same manner as you do to disconnect pretty much every similar connector on a VW (coil packs connectors, HPFP connectors, etc.). This one is no different, just need to get access. With that done you should be able to carefully pull the N75 straight up and out from the topside.

Re-installation of new N75 should be pretty straightforward reverse of what you just got done.


Hope this is at least somewhat helpful. Btw, ignore the coolant splashed on some of the stuff, that happened while I was doing the other job I mentioned before eyeing up the N75 situation...


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## APURPLEKING (May 23, 2007)

Not to bring this back from the dead...but...

I'm currently in the process of doing (or trying) this.

1)I can tell you that the bracket 10mm bolt does not let the n75 valve loose.

2)The two n75 bolts are T25 and aren't on there very tight. I got the first one off from above but the second will most likely need to come off from below. 

3)Even IF I get this thing off getting the bolts back in to install the new one will be a HUGE PITA! 

I got rained out before I could get the car up in the air, so I'll report back in a day or so.

Happy 4th ya'll!

Sent from my SM-G900T using Tapatalk


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## vtraudt (Mar 1, 2010)

What are symptoms of a 'lazy' N75? 
I am getting a bit of a boost over-swing when turbo comes on. Stock as well as stage 1 tune.


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## Thy_Harrowing (Dec 7, 2014)

vtraudt said:


> What are symptoms of a 'lazy' N75?
> I am getting a bit of a boost over-swing when turbo comes on. Stock as well as stage 1 tune.


Ultimately you're gong to want to data log your waste gate duty cycle to make the determination on whether your N75 is behaving correctly. See my thread below (you can skip to posts #39/40 and #47). It may not have been the issue you are facing but you'll learn what to look for regardless

https://forums.vwvortex.com/showthr...-WOT-only-Seemingly-NO-boost-loss-or-vac-leak!


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