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Vaccuum line sizes and length?

58K views 16 replies 6 participants last post by  MKK 
#1 ·
Hi everyone,
I'm one of the unlucky ones getting the P0234 overboost error code on 2002 Vw bora ALH. Have gone through most minor possibilities and am next going to replace all the vaccuum lines. I have read somewhere that there are 3 different diameters of vacuum hose that will need replacing. Does anyone know the approx distances needed for the various diameters? Have had visions of having to take one hose at a time to parts store to ensure correct replacement.
If this doesnt fix it I will be back with more info.
Thanks for reading.
 
#2 ·
I can't tell you the size of these vacuum lines but:

VAG Error Code: 16618
EOBD II Error Code: P0234

Fault Location:
Boost Pressure - Regulation Limit Exceeded (Overboost Condition)

Possible Cause:
Malfunction Indicator Lamp (MIL)(K83) ON.
Boost Pressure too high.
Reduced Power Output.

Hoses incorrectly connected, disconnected, blocked or leaking.
Boost Pressure Control Valve (N75) faulty.
Boost Pressure Sensor (G13) faulty.
Turbocharger (TC) stuck/faulty.

Possible Solutions:
Check Charge Pressure Control System.
Perform Output Test (to check the Turbocharger (TC)).
Perform Basic Setting (to check the Charge Pressure Control).
Perform Pressure Test to locate Leaks.
Check/Replace Boost Pressure Control Valve (N75).
Check/Replace Boost Pressure Sensor (G13).
Check/Replace Turbocharger (TC).

As taken from my http://www.myturbodiesel.com/forum/f9/free-eobd-ii-error-codes-software-2919/
 
#4 ·
You need 3 meters of 3mm and 1 meter of 5mm, you'll have a leftover of the 3mm but not the 5mm.
I replaced mine as they were badly chaffed and instead of buying OEM, i purchased samco high quality silicone vacuum lines (they're really thick) and added heatshrink tubing at every places were it was clamped or it could wear... I was also able to label them to the correct colors!

The only thing that broke in the install is the support for my N239 valve, and i have yet to repair it, i think i'll try abs cement



Sent from my BlackBerry 9300 using Tapatalk
 
#5 ·
Thank you Keith, Seatman and Cr3zy for the quality info. The map sensor has just arrived so am going to swap that 2mos along with all the vacuum lines I can find! Will check actuator rod for free play n insert mr muscle (thanks for cool link) if needed. Will update ASAP with results. Cheers.
 
#6 ·
I recently replaced all my vaccum hoses with silicone too. I looked around quite a bit on the forums for the right tubing, and settled with the stuff at http://boostcontroller.com/index.php?category=8 Seems to be very durable and high quality. You have to buy a minimum of ten feet of any given diameter, but they are priced reasonably, and it doesn't hurt to have a bit extra. I got 12 feet of 3mm inside diameter (ID) and 10 feet of 5 mm ID and it worked great. Shipping was very fast too. And yeah, only replace one section at a time, you'll have better luck ensuring that it goes back together the right way! ALso just cleaned out my EGR and intake manifold with degreaser, that's not a bad idea either. Goodluck!
 
#9 ·
As Seatman said, yes, it is most practical to remove the EGR and intake for cleaning. I followed the walk through from this site ( http://www.myturbodiesel.com/1000q/a4/clean-intake-manifold-VW-TDI-carbon.htm ) and it made it very systematic and not too difficult. Be sure to have a set of allen wrenches handy and consider labelling sensor plugs, vacuum hoses, and bolts with tape as you remove them. The EGR comes off, then the intake cooler, then the intake manifold. The toughest part is that all of the bolts for the intake and cooler are facing the firewall, so you essentially have to go just by feel and check with a mirror. Again though, the walk through is a lifesaver.

To clean the EGR and intake manifold I used a generic Autozone "Engine Degreaser" from an aerosol can and it seemed to work great. First I carved out major build up with a flathead screwdriver, then I powerwashed the insides, then applied the degreaser, let it sit for ten minutes according to the can, and used a wirebrush to get the residual carbon buildup. I was amazed at how much gunk was built up in there; it made cleaning it all out seem worth the effort. The EGR is easier because it doesn't have the hard-to-reach inside corners that the intake manifold does, but the majority of the buildup is near the openings anyways I found.

The reason you want to remove them for cleaning is so that you don't knock chunks of crap into your engine that could be scraped around by valves or pistons. One tip that might help-- when you unbolt the intake cooler, you don't have to disconnect the 3 radiator hoses attached to it unless you intend to clean that too. You can leave those attached and then just tie the cooler off to the side. It remains connected by the hoses, but it's got plenty of space to be moved.

Also too, if you have any inclination to remove the exhaust manifold or turbo, this would be the time to do it, as both will be as accessible as they will ever be from above with the EGR and intake removed. I had already ruled stuck vanes out, so I left the turbo in, but it was at least neat to get to see it for once.

Just go slow and be sure to label or keep track of things, re-assembly isn't bad. All told, the process probably took me 3 or 4 hours, but I wasn't in any particular rush and hadn't done this before.

Best of luck, and feel free to ask any more questions you might have!
 
#10 ·
Hi guys,

thanks for the second lot of info. I have messed up while replacing the vacuum lines on the reservoir ball and the vacuum end of the of the plunger on the anti-shudder valve because while removing the 10 year old hoses the air nipples broke off at the root despite being careful.

Have tried super glueing them back on but they apparently arent made to be repaired. Have sourced a replacement ball but have no idea of the part number or name of the plunger doohicky. Does anyone know the name or part number or perhaps is it stamped on there somewhere?

I did the hose down the turbo trick but couldnt see much from the mirror so hopefully the oven cleaner did go down the turbo and not into the cylinder head.

Because of the disconnected piping I havent drove the car and the oven cleaner is still in there somewhere. Will I be able to drive the car prior to connecting the hoses to the anti shudder thing and the vacuum ball? At the moment am going to borrow the wife's car to collect the vacuum ball.

Cheers, Phil
 
#11 ·
The lack of the Anti-Shudder valve won't prevent you driving, because it is normally open I believe. The vacuum line attached to it closes the block off plate when you turn the ignition off to help make shutdown smoother, but a lot of people eliminate their ASV entirely when they remove the EGR for an EGR delete or race pipe alternative, so it's obviously not essential. I'm contemplating scrapping my EGR completely here pretty soon. Depending on where you live though, you may have certain emissions standards that would require it to be left on. I hear you though as far as breaking the nipples; I snapped one on my N75 :annoyed Interested to hear how everything goes-- Good luck!
 
#12 ·
Hi Hoff, thanks for your reply.

Well, I spent the better part of the morning driving miles to collect a second hand vac resorvoir from a vw scrapper and then hunting down vacuum hose as the three automotive stores I went to don't stock it any more. In the end, some 6 mm was sourced from a hose supplier on an industrial estate. He didnt have 5 mm. But what difference will a mm make? Its not like we're talking engine internals?

Well it made plenty of difference in the sense that a couple of the connections were too sloppy and just not fit for purpose. So, will just order some more online. The vac resorvoir went on a treat and crossing my toes while connecting the new hose to the fragile nipple did the trick.

Took it for a nice long drive afterwards and there is very little smoke coming from the exhaust now but the performance is the same. Accelerates smooth and fast down hill, can get up to 70 mph on flat stretch of motorway but going up any sort of moderate incline she just falls flat on her butt!

So, tomorrow morning am going to remove the bumper and clean/replace the MAP sensor to see if that might be the culprit. Failing that will look at replacing the n75 valve and after that cross more body parts. Lol
 
#15 ·
Hi Seatman,
yes I have squirted oven cleaner into the turbo but it doesnt seem to have made much difference. It did pull well in 3rd after a long drive but thats about it. Have taken the front bumper off to replace the MAP sensor but unlike the Youtube video where the sensor is in plain view mine is tucked away out of sight near to the windscreen washer bottle! So have taken the intercooler completely off to get access to the map sensor holding screws only to find they wont budge! Aarggh! They must be loc-tited in at the factory. So will take it to a garage tomorrow for screws to be extracted.

When I removed the intercooler there was a small pool of oil in it. Is this normal or is something seriously screwed up?

Regards, Phil
 
#16 ·
Hi guys,
Have finally solved the mystery. Turns out the overboost was caused by a dodgy N75 valve which I have replaced from my local breakers yard for £10! Wish I had started with the simple stuff first! Lol Although she has now had a healthy dose of tlc including some oven cleaner in the turbo. Thanks to everyone for viewing and helping and a big thank you to the guy who created the thread suggesting swapping the N75 and EGR valves to diagnose it. Cheers, Phil
 
#17 ·
Vacuum Reservoir replacement

Hi Hoff, thanks for your reply.

Well, I spent the better part of the morning driving miles to collect a second hand vac resorvoir from a vw scrapper and then hunting down vacuum hose as the three automotive stores I went to don't stock it any more. In the end, some 6 mm was sourced from a hose supplier on an industrial estate. He didnt have 5 mm. But what difference will a mm make? Its not like we're talking engine internals?

Well it made plenty of difference in the sense that a couple of the connections were too sloppy and just not fit for purpose. So, will just order some more online. The vac resorvoir went on a treat and crossing my toes while connecting the new hose to the fragile nipple did the trick.

Took it for a nice long drive afterwards and there is very little smoke coming from the exhaust now but the performance is the same. Accelerates smooth and fast down hill, can get up to 70 mph on flat stretch of motorway but going up any sort of moderate incline she just falls flat on her butt!

So, tomorrow morning am going to remove the bumper and clean/replace the MAP sensor to see if that might be the culprit. Failing that will look at replacing the n75 valve and after that cross more body parts. Lol
I suspect that I have a Vacuum Reservoir Ball leaking as had a limp mode problems myself on my Passat. In my case the turbo boost pressure was not reaching the required level so there must have been a leakage somewhere and upon blocking the hose leading to Vacuum Reservoir Ball we were able to get the boost pressure required and turbo started to kick in properly as the stats on diagnostic tool suggested. At the moment we suspect the Vacuum Reservoir Ball is the culprit and would probably need replacing. So as you had replaced yours

Do we have to take the Air conditioning pipes off to get the Vacuum Reservoir Ball taken off? On our first attempt yesterday it won't come off as there isn't just enough space for it to come off.


Secondly can we not get a new one as you had in your case sourced one from the VW Scrapper or the new one really dearer.

I am from Burnley so it will be helpful to know about the VW scrappers in the area. I have searched online for the Vacuum Reservoir Ball but to no avail.

Will appreciate your help.

Thanks
 
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