Allroad 2.7t Turbo boost pressure leak

[snugglebum]

Hi guys
Over the last few months I've noticed a loss of power and engine surging when lightly accelerating. After some investigation and googling I'm pretty sure I've got a leak on the charge side of the turbo pipe work, or a faulty DV/N75 valve.
I haven't had much luck with mechanics in recent years, so can anyone recommend a garage/mechanic that has the right equipment to pressure/smoke test the pipe work?
I live in Barnsley and work in Sheffield, somewhere close ish would be ideal but I'd be willing to travel.

Cheers
Lee

[kid-jensen]

I have a similar lack-of-power problem, but there's not many petrol engined Allroads sold here so less chance of someone being able to help..

Looking at doing a leak test myself, seems straightforward enough. Just come up with the means to supply air (up to say, 12 lbs pressure) into the "Y" inlet manifold and listen for leaks.

I've got as far as a "regulator" type device which can set the maximum pressure level, and by using this I am guessing I can use a tyre to supply the air. I prefer this because the compressor noise will make listening for leaks more difficult (and a Hafords 12V compressor might not have enough capacity).

Not tried it yet as my crap measuring of the inlet diamater made me buy the wrong size hose...

So, at the moment I am looking for a short bit of rubber hose 86mm inside dia, and something to block up the open end..

You can buy boost leak testers for about 35 quid, (no regulator), here:-

http://www.turboboostleaktesters.com...UDI/Categories

But....... I've put quite a bit of money into mine already and I want to keep the costs down in case it turns out to be something else..

[snugglebum]

Hi Thanks for the link to the preassure tester. Ive bought one and gonna give it a go myself.
Ive got a friend who owns a garage but he services HGVs, anyway he says i can use one of his ramps and air line on a Sunday.
The only thing i think i may need is a 1" cap any ideas where to get one?
Cheers
Lee

[kid-jensen]

I've got one but it's made of polythene, so it's a bit slimy and will need a Jubilee clip.

PM me and I'll put it in an envelope...

[kid-jensen]

Lee,

Any progress?

I'm desperate to get my car performing as it should, and I'm also a bit windy that the turbos maty be overspooling if there's a leak...

[snugglebum]

Hi sorry i haven’t replied but we have been away.

Thanks alot for sending me the cap mate, sorry again for not letting youknow id received it but it arrived the day before we flew and things werepretty hectic.

Ive got the pressure tester too so ive got my friend garage booked for thisFriday and hes gonna give me a hand with it too.

Ill update you at the weekend....hopefully ill have a powerful allroad withno engine surge!

Cheers
Lee

[kid-jensen]

That's great....I'll get myself positioned on the edge of my seat!

[snugglebum]

Right where do I start!

Firstly I'll have to keep it short because I'm out with the missis posting off my phone. But I really wanted to update and throw some ideas your way.

The pressure tester worked perfectly, but the 1" cap didn't seal even with the jubilee clip holding it so we managed to improvise with some hgv air line and some mole grips. But the pipe we were blocking off that supplies the SAI pump was very brittle and broke off so we had to repair it. I've ordered a replacement Y pipe off eBay for £22.
The pressure tester showed up 2 leaks on my turbo pipe work. The first was on the right DV and the second was on the left inter cooler. A good cleanup and new jubilee clip fixed them. We then had a slow leak from the back of the engine near the N75 valve that we couldn't find. After some googling I found out you need to block off the pipe with blue writing on to that's connected to the N75 to perform the pressure test. Crimped it and presto no leak.

Road tested the car....it had more power but still has the engine surge!

My friend was more concerned about the exhaust blowing sound the car makes on cold startup. I thought this was the SAI pump and was normal. But I do get the exhaust blowing sound when the engine surges / looses power. My friend thinks the EGR valves my be to blame for this? I had to leave it there so we didn't investigate it.

So do you get the exhaust blowing sound on cold startup? I do have fault codes for the SAI pump now and then do you?
If you want to borrow the tester pm me and I'll send it too you.

Please excuse and rambling and mistakes as ive had a cpl of pints
Lee

[kid-jensen]

Lee,

Thanks for getting back and risking your night-out with the missis...

There's a lot of issues here so I'll reply within the body of your text..

Firstly I'll have to keep it short because I'm out with the missis posting off my phone. But I really wanted to update and throw some ideas your way.

The pressure tester worked perfectly, but the 1" cap didn't seal even with the jubilee clip holding it so we managed to improvise with some hgv air line and some mole grips.

Sorry about that, I was convinced it would be man-enough but obviously didn't get the chance to find out.

But the pipe we were blocking off that supplies the SAI pump was very brittle and broke off so we had to repair it. I've ordered a replacement Y pipe off eBay for £22. The pressure tester showed up 2 leaks on my turbo pipe work. The first was on the right DV and the second was on the left inter cooler. A good cleanup and new jubilee clip fixed them. We then had a slow leak from the back of the engine near the N75 valve that we couldn't find. After some googling I found out you need to block off the pipe with blue writing on to that's connected to the N75 to perform the pressure test. Crimped it and presto no leak.

Brilliant....so the actual test was the easy bit then. How did you pressurise it and what pressure did you need to reveal the leak?

Road tested the car....it had more power but still has the engine surge!

What a pain, wish I could suggest a reason, but I've never had the surging problem.

My friend was more concerned about the exhaust blowing sound the car makes on cold startup. I thought this was the SAI pump and was normal. But I do get the exhaust blowing sound when the engine surges / looses power. My friend thinks the EGR valves my be to blame for this? I had to leave it there so we didn't investigate it.

The EGR valve(s) sounds likely to be the problem, particularly as you hear the noise at the same time. I need to re-read the self-study article on how the engine works.....always a good idea when it doesn't! The "exhaust" noise on every cat-equipped car I've had, was the SAI pump (switches-in when cold to light-up the cats for a minute or so). As the noise stopped after a minute, I didn't worry about it, but in your case it might be something else. There's a lot of faults that sound like exhaust leaks unfortunately.

So do you get the exhaust blowing sound on cold startup? I do have fault codes for the SAI pump now and then do you?

Yes, I certainly do, but I've never worried about it because I was sure it was the SAI pump.

If you want to borrow the tester pm me and I'll send it too you.

PM on it's way.

Please excuse and rambling and mistakes as ive had a cpl of pints

This post makes a lot more sense than most of mine do when I'm stone cold sober!

[snugglebum]

Finding the leaking joints was very easy! I eventually got the tester with the tyre valve on it, so we just used the air line and the tyre inflator to pressurise the system. We pressurised it to 15psi then just listened for the leaks, they were very easy to pinpoint without using soapy water. At first the pressure was dropping very quickly (1-2 seconds) so the leaks were fairly major. I don't think you could use a 12v tyre pump as if you had a major leak it wouldn't get the pressure in quick enough, also the noise would dround out the hissing.
I'll post the tester on Monday but you will need to find a 1" rubber cap....sorry I've managed to loose the one you sent me!