Project 46 is an on-going series that demonstrates common fixes and preventative maintenance tips, as performed on our own E46 330Ci. Click here to read our introduction to the series.

As we mentioned last week, one of the first things we noticed when we took the 330Ci home was the erratic idle. We initially replaced the mass airflow sensor which fixed the cruise control and made a noticable difference to the way the vehicle drove, but the idle remained unsettled. After last week’s blog post, we pulled the DISA valve out to inspect it. The DISA valve is one of the more common parts to fail on the E46, so it was no surprise to find the internal flap completely detached from its housing. More concerning was the locking bolt just sitting freely in the intake manifold. Had that bolt been sucked into the motor, it could have caused a catastrophic engine failure. Not an ideal scenario after a week of ownership.



While half the components were off, we also decided to take a look at another weak area on the E46: the crankcase ventilation system (also known as the oil separator system). In the few days since we took delivery, the car had developed an odd and inconsistent clanging noise from somewhere at the top of the motor, which we realised was related to a problematic CCV. We found that the dipstick hose was completely severed and the upper oil separator vent tube had developed a crack, causing a vacuum leak. With all the parts being very brittle, some of them snapped during removal. A good reason to replace all four hoses when doing the job. As well as all oil separator hoses, the crankcase ventilation valve and the DISA valve were all replaced with brand-new parts from Vaico. After removal, it was clear to see just how clogged the original crankcase valve was with oil sediment.

Once everything was back together, the vehicle was started and the idle settled into a familiar purr, without any sign of that horrendous clanging noise. With the DISA valve installed, the engine delivered noticeably more low-to-mid range torque, improving the drivability of the car considerably and fixing the idle issue once and for all.  

When replacing the DISA valve and the crankcase ventilation system, we also noticed that the left-hand engine mount had disintegrated (something that really should have been noticed when the roadworthy was done the week before). Both engine mounts were swapped with replacements from Febi-Bilstein, fixing a background vibration that had been felt at idle and on acceleration. It’s always best to replace all engine mounts at the same time.


As our hands were already greasy, we decided for peace-of-mind to put one of our popular Oil Change Kits through the motor. The kit includes a new oil filter from original equipment manufacturer Mann, and BMW Longlife-01 approved oil from Motul. The X-cess 5w40 motor oil is 100% synthetic, providing greater heat stability and resistance to oil burn. Although it’s not the cheapest oil on the market today, we consider it to be cheap insurance. It’s a good thing we decided to perform the oil service as the oil filter we removed from the motor was very dirty and had started to collapse in on itself.

This week also saw the interior get a bit of attention. The seats, although generally in good condition and not yet to the point of cracking, were still quite dirty and noticeably dry. After a going-over with Autoglym’s Leather Cleaner, some Autoglym Leather Care Balm was applied to the seats. The job provided some much-needed moisture, in-turn restoring some lustre back into the black leather, and also immediately reinstating a rich leather smell to the BMW’s interior. As well as extending the life of the seats, it made the cabin a much nicer place to be.


It’s worth mentioning that the 330Ci we purchased is actually in very good condition, with basic maintenance performed fairly regularly by past owners. The components we’ve replaced were exactly what we were expecting to need replacing as they are the most common parts to go on the E46. Now that these simple components have been replaced, they won’t have to be looked at for another decade.


New Mechanical Repairs:
Oil Change Kit - Motul X-cess 8100 - $147
DISA Valve 3.0 - $265
Engine Mounts - $160
Crankcase Pressure Regulator Valve (Oil Separator) - $55
Upper Oil Separator Vent Tube - $30
Crankcase Ventilation Hose - $25
Crankcase Ventilation Hose - $15
Oil Separator Return Pipe - $28
Total Cost of Repairs: $1059

New Non-Essentials:
Autoglym Leather Cleaner - $24
Autoglym Leather Care Balm - $26
Total Cost of Additions: $62

Total Cost To Date: $1121


Ben@Clickable says

posted on 19/06/2017 1:13 pm

Hi Perry, it could certainly be a symptom of a failed or blocked CCV system. Our recommendation would be to have the issue diagnosed by a qualified mechanic just to make sure there isn't something more serious at play.

Perry Guymer says

posted on 19/06/2017 1:09 pm

G'day guys. I drive a 2001 320i auto sedan. I was returning home from a drive on country roads recently when after decelerating from 80kph to almost stopped for an intersection I noticed a huge plume of grey smoke behind the car on acceleration...PANIC! Since then I notice smoke whenever I accelerate after slowing down, none or very little when just revving the engine stationary. I've been researching on the net to try and get an idea of what the bad news will be. Just wondering if you think it may be a failed CCV or something more serious? By the way, I had done an oil change the previous week using Castrol Edge 5W30 & fresh filter.

Ben@Clickable says

posted on 25/01/2017 1:23 pm

We've just sent some emails to those who were asking specific questions about issues on their vehicles. Ben

Anthony WEE says

posted on 9/02/2016 10:58 am

E46 2003 320i

Have changed the camshaft position sensor(intake side), temperature sensor, fuel filter and oil separator CCV - kit. Though it has improve the fuel consumption and improve the torque. The idling issue still remains.

Cold morning start - engine runs rough and takes a few minutes to warm up before running smoothly.If drive without warm up (temperature meter does not show 50%) engine lost power and if continue without stopping the cranking sound appears, Check with my usual workshop and they told me that the mass air meter and DISA are working. No immediate change is necessary. Car has run 170000 km and was 90,000 km when bought.

Any suggestions to my dilemma ?


marsman says

posted on 7/02/2016 2:42 pm

Hey guys great update to the "project" and good to see someone who is "involved" with their car and provides feedback to customers. You guys have been excellent to deal with parts arriving quickly and at a fair price IMO.
You mentioned changing out the engine mounts to fix a background vibe on acceleration; I have (2004 ,325ci) which has an annoying vibe on acceleration , I was heading towards a trans fluid change and flex coupling and bearings on the driveline ; did your mounts fix the vibe??
great job keep it up guys.

Mark Duggan says

posted on 15/01/2016 1:03 pm

Hi I have an E30 that has the same idle issue, could this possibly be the same cure? I have replaced the airflow sensor. Cheers, Mark

Geoffrey Haines says

posted on 8/06/2015 2:15 am

Just started reading project 46 and I am enjoying it immensely, just hoping that your heater blows hot air on the passenger side and cool air on the drivers side so I can find out what the cause of this problem is,,as it is driving me mad not being able to pin point the problem,,ANY IDEAS would be appreciated,,

Steven Jones says

posted on 29/09/2014 3:09 pm

Hi guys
After reading this I decided it would be a good idea to check the DISA valve on my E46 325i which has 197 000 Kim's on it. I removed the valve and had a look at it and it actually is very healthy mechanically wise, the flap is secure and moves freely and if I cover the vent hole for the vacuum diaphragm once I have pushed the flap closed it will not snap open until I uncover the hole, all good. My issue though is that with the valve installed and engine idling the flap stays open, sometimes if you rev the engine up slightly the flap will snap closed and if you keep revving it it will snap open, sometimes it doesn't do anything.To cut a long story short the disa flap appears to only operate intermittently. It is my understanding that it should be closed always at idle and only opens higher in the rev range, is this correct? If at idle I remove the plug and check using a led test light there is power at the plug, so I am sure the issue is not electrical. I have owned this car for 4 years,it is manual and I have always found it intermittently very easy to stall, but at other times not. I believe this is probably due to intermittent disa valve operation. Just as a footnote I am checking the operation of the valve by observing the actuator rod.

Simon Inga says

posted on 28/09/2014 10:14 am

Thanks for the tips for idle problems!

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