About to do an N75 valve change 996 Turbo...any tips?

Afternoon All, As per title, I am about to complete an N75 valve change (to try and cure some over boost issues as per the below 'DIY' (don't shoot, I know its from another forum)... http://www.6speedonline.com/forums/996-turbo-gt2/206000-n75-diy-thread-overboost-surging-fix.html Just wondering if there is anything else I should be aware of or any hints and tips before I get started??? Cheers, Tony

It sounds as though you need a descent indy to get alot of small jobs sorted.

Ken from 9e mentioned these to me in a recent post re things to do at a service. Might be worth getting his view, he seems incredibly knowledgeable!!! :worship:

I did this on mine last year....it's a really simple job if you follow the steps in the link you posted. N75 replacement went really smoothly for me and cured my overboost / surging issue straight away. However I have removed the Y-pipe a number of other times since and on one occasion managed to damage the small rubber pipe which comes out of the back of the N75 and goes into the Y-pipe. I think you can avoid damaging it if you remove the pipe from the N75 before unclipping and sliding the N75 back off the bracket. I left the pipe attached and it bent back on itself, causing the perished rubber to split. The pipe & clip were only around £10 from the OPC but better to save yourself the hassle if possible. Hope this helps

Did mine this afternoon, ten minutes and didn't remove any of the stuff that guide tells you about! It is fiddly but you don't need to do all that.

Hacka, many thanks for that Just the sort of helpful advice I was after Isoproturon.... I think you didn't have to move anything because you may have a slightly different spec turbo which doesn't have the secondary silver pipe covering the N75 To be honest, I haven't done it yet (got busy) so will try tomorrow if not Monday ...so...any more helped advice anyone? ... Or do you think I will be ok with the above link and advice?

With the right tools and some patience, I can see how it may be possible to do the N75 without removing the Y-Pipe. But for me it was a lot easier to just take the whole Y-Pipe assembly off (only 3 bolts and it just pulls out). I believe that overboost could also be caused by a boost leak. Might be worth doing a leak test if the new N75 doesn't resolve your problem. I bought a tester from turboboostleaktesters.com for about £30 but it is possible to make one cheaper by buying the parts and assembling yourself. I found a major leak on the inlet piping into my drivers side turbo. Patched it up and the car was noticeably quicker and more responsive afterwards

Hi Hacka... So did you do the N75, then notice the car was all better? But then did the boost leak check too anyway? Or did you do the N75 and the boost leak check/patch up together at the same time? Tony

Do you have a US spec car ??? With a fuel cooler.

Not long after I got the car it started overboosting...I was seeing spikes up to 1.4 bar on the display and the car felt noticeably down on power. Replaced the N75 and that completely sorted the issue. Boost was back to 0.7 bar as the car was stock at this point. Since then I have done a lot of mods and upgrades (remap, exhaust, ICs K16 billet turbo upgrade) and I'm now running 1.3 bar. I thought it would be a good idea to check for leaks while doing the upgrades and glad I did as the intake system wasn't holding any pressure due to the size of the leak After I fixed the leak, the indicated boost didn't change but the boost seemed to come on sooner with less lag and the car also seemed noticeably quicker. However I believe it is possible for some leaks to cause overboost. Overboost could also be caused by a stuck wastegate. Have you checked whether your wastegate arms move freely ? You should be able move both arms with your finger....if not they could be stuck shut which isn't good !

Thanks for that Hacka, much appreciated. May look into getting one of those boost leak check kits and doing that. I love learning/working on cars etc (I have a desk job 9-5 so this is about as much fun as I get).. Anyway, by saying I should be able to move the wastegates....(forgive me if this is completely wrong as I am a novice) ...but do you mean if I jack the car up, get under it and push some sort of 'stick' (my sticks looked rusty) by the turbos I should be able to move it back and forth (seems to be spring loaded??) and hear it move inside the turbo ? If so, I believe yes the wastegates move freely (although seem spring loaded as advised) as I recently got under the car and pushed both sides back and forth just to check.

test

No.

Not you dude the OP, like you say no need to remove the Y pipe.

Hi there It's a standard RHD car If the 'additional' silver pipe which seems to run over the N75 is a fuel cooler pipe then yes I have a fuel cooler pipe. Not sure if it denotes USA spec though as another member in the N75 DIY thread also had this pipe and he resides locally to me (Sutton coldfield, UK) Did people understand what i Meant by 'moving those sticks' which seemed spring loaded? I'm assuming they are actuator rods which control the waste gates?