N52 DISA failure - a few questions

[Beesza]

Evening all,

I’ve had my 3.0si for a few months now and whilst scrolling through the “How-to’s” on this forum, I spotted the thread on DISA valves and thought I should check the condition of mine.

I set about removing the airbox upper, inlet tubing and throttle body to get to the DISA, removed it and “where the * has the valve gone?!?!”. Managed to fish the vane out of the air manifold. Replacement DISA needed. This explains the occasional rough idle I was experiencing.

Questions:
1. I think there is a second DISA valve on the internal side of the manifold. Is it worth removing the manifold to check on this one? Most of the DISA commentary online seems to focus on the larger DISA that I have removed. Just wondering as I’ll have to order new manifold gaskets to check this. But if I need to replace the other DISA as well, it is cheaper to buy both as a bundle.

2. There was a fair bit of oil on the DISA as can be seen in the photos. Is this normal? Is this a symptom of another issue?

3. Are the manifold bolts torque-to-yield and therefore I’d need to replace these as well?

Thanks for any help/guidance

[Smartbear]

It’s the ccv that regurgitates oily engine fumes into the inlet manifold, sooting up the plugs/piston rings as it goes
Rob

[Beesza]

Is that just how the CCV works i.e. doesn’t do a great job at separating the oil and air? Or is it a sign that the CCV needs something doing to it?

[E86]

Good work, I should check mine too...

There is a second smaller DISA value. I saw a youtube video replacing this without removing the inlet manifold, although the alternator was removed for access. (here, it's an N52 in a 1 Series, Z4 might be slightly easier). There's another video for the large DISA.

What replacement valve will you use? OEM? There are aftermarket repair kits which replace some of the plastic components. e.g. small & large.

[Beesza]

Managed to get the small DISA valve out following that video. My engine had a additional pipe running between the manifold and engine block which was in the way of removing the small DISA but I eventually wriggled it out. It was in ok condition. No play in the vane but some of the green rubber was missing. Probably good enough to go back in.

I’m going to go for a whole new large DISA. The spindle was spinning freely and I’m amazed to see the hex on the metal spindle has rounded where as the hole in the vane still looks good. Now to decide between OEM, reputable aftermarket or Chinese copy…

Part of me says go cheap as this valve is for low end performance and the car felt fine with the broken valve. The more sensible side of me says I don’t want another broken part which could be ingested into the cylinders.

Does anyone have experience with aftermarket DISAs?

[Smartbear]

Is that just how the CCV works i.e. doesn’t do a great job at separating the oil and air? Or is it a sign that the CCV needs something doing to it?

Hi, its usually a sign that the ccv needs replacement
Rob

[WouterZZZZ]

When the smaller DISA looked like on the enclosed photo in my E85 3.0si N52, it turned out the ccv needed replacement like Rob says. The oil and air separation was not there anymore and the oil had eaten rubber parts of the smaller DISA. We replaced the full ccv (tubes included).

[WouterZZZZ]

In addition to answer your question, the Febi Bilstein aftermarket DISA will do a proper job.

[E86]

I don't think it's mentioned in that video but the alternator mounting bolts are aluminium and should be replaced.

Part number for replacement set of bolts is 12310392568

12 31 020 - Removing And Replacing Alternator N52.png (209.96 KiB) Viewed 823 times

12 31 - N52 Alternator Torque.png (42.97 KiB) Viewed 823 times

[Beesza]

Thanks for the guidance gents

I’ve ordered a secondhand OEM DISA from eBay. (In the post now). My Zed is a weekend toy so doesn’t do many miles plus it felt great with a broken DISA so I’d prefer to spend my pennies elsewhere. Didn’t want to chance it with a Chinese replica and figure a good condition used one would have enough life left in it for my purposes. Time will tell if this was a good decisions or not.

Yep, they are torque to yield bolts… love them. EBay is asking for £15 for 4 bolts. Seems a bit steep

CCV - yes, I’m rather concerned with how much carbon there could be in my cylinders with all that oil in the manifold. I have an N52K (black engine cover) therefore my CCV is integrated into the valve cover. I think I’d need to replace the rubber diaphragm inside it but that also requires a new gasket and bolts.

Is anyone aware of a CCV servicing video/guide for the N52K engine?

[Smartbear]

Thanks for the guidance gents

I’ve ordered a secondhand OEM DISA from eBay. (In the post now). My Zed is a weekend toy so doesn’t do many miles plus it felt great with a broken DISA so I’d prefer to spend my pennies elsewhere. Didn’t want to chance it with a Chinese replica and figure a good condition used one would have enough life left in it for my purposes. Time will tell if this was a good decisions or not.

Yep, they are torque to yield bolts… love them. EBay is asking for £15 for 4 bolts. Seems a bit steep

CCV - yes, I’m rather concerned with how much carbon there could be in my cylinders with all that oil in the manifold. I have an N52K (black engine cover) therefore my CCV is integrated into the valve cover. I think I’d need to replace the rubber diaphragm inside it but that also requires a new gasket and bolts.

Is anyone aware of a CCV servicing video/guide for the N52K engine?

Think I’ve seen utube vids for this, there’s also a website for a company making replacement diaphragms as i don’t think bmw supply them. https://www.google.co.uk/url?sa=t&rct=j ... ExgDbi-rxq
Rob