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Discussion Starter · #1 · (Edited)
Just after some guidance re replacing the cam cover gasket as I have found oil in a spark well or two on my 125i, which I believe is causing a misfire and sluggishness. I also may have a small leak underneath the Valvetronic motor gasket.

Im in the process of getting quotes and some specialists have advised to replace the whole plastic cam cover aswell. Would this be overkill or is it likely at 101,000 miles this may be damaged/warped. I would imagine this is quite a bit more expensive. While its all apart is it also a good idea to replace the Eccentric shaft sensor, there's no signs of oil in the sensor plug. Im not getting any codes so far only the misfire that the specialist found using BMW software.

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Just after some guidance re replacing the cam cover gasket as I have found oil in a spark well or two on my 125i, which I believe is causing a misfire and sluggishness. I also may have a small leak underneath the Valvetronic motor gasket.

Im in the process of getting quotes and some specialists have advised to replace the whole plastic cam cover aswell. Would this be overkill or is it likely at 101,000 miles this may be damaged/warped. I would imagine this is quite a bit more expensive. While its all apart is it also a good idea to replace the Eccentric shaft sensor, there's no signs of oil in the sensor plug. Im not getting any codes so far only the misfire that the specialist found using BMW software.
There's a few N52 oil leaks that seem incurable, even after replacing valvetronic, eccentric, spark plug tube, and rocker cover gaskets, and it's because the plastic cover has a hairline crack.
 

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Discussion Starter · #3 ·
Maybe a good idea. However there is a fear at the back of my mind that the misfire remains even after replacing all this. I dont have much to go by other than oil in spark wells and they were replaced in 2019 on history. Disa seems good, Vanos solenoids clean, PCV also seems ok. Does ESS or Valvetronic usually produce codes when on its way out?
 

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There's a few N52 oil leaks that seem incurable, even after replacing valvetronic, eccentric, spark plug tube, and rocker cover gaskets, and it's because the plastic cover has a hairline crack.
Yep.. I was investigating a weepy valve cover gasket, only to find a hairline crack front offside corner of the valve cover.
I'm very glad I found that before doing the gasket swap. !
After that another leak was found due to the valvetronic motor face being slightly bent so was not sandwiching the valvetronic gasket well enough.

Have you inspected the plugs?, oil around them is a worry but not enough to cause missfires unless the oil has seeped down to the tips.
if they're clean, would ignition coils be the next area to look at?
It might be worth a vanos solenoid replacement, rather than clean.
 

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Discussion Starter · #5 ·
Ive managed to replace the coil on the cylinder with some benefit but still with a lumpy irregular idle. As theres oil on a plug or two that was my next logical step but i find with these engines theres so many things it could potentially be. What signs would a faulty injector be out of interest. Thats the only other thing i could think that would cause a misfire on one cylinder that I haven’t ruled out already.
 

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Replacing the cover is a good idea but not strictly necessary - the garage could just inspect the old one and advise. You can buy aftermarket covers to save money (genuine are ~£400), but always use a genuine BMW gasket as it seems just about everyone who doesn't regrets it in short order.

Eccentric shaft sensor is £200ish for an OEM Siemens/VDO part. The often fail because of oil ingress, if you don't let that happen they seem to last forever so the choice is yours.. Definitely change the gasket, it's cheap as chips.

You can swap the injectors around if need be. The N52 has good old port injection, no need to replace the injectors en masse and code them like you need to with the N53+. That said, if it's a garage doing the work it's probably cheaper to just replace it, should be around £100 for an OEM part (again Siemens/VDO).

I agree with MED, inspecting the plugs is a good idea. An incorrectly-gapped plug could easily cause a misfire.

Also, possibly something that's already been covered, but have you had your car updated? There's a firmware update for the DME to fix a persistent rough idle, see my post here 130i rough idle issue (misfire?). Any dealership or approved specialist can do it, worth checking both as sometimes the dealerships actually come out cheaper.
 

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My 130i had a slight weep from the rocker cover and an eccentric shaft sensor with oil in he connection. I racked the changes myself and discovered that the rocker cover had a crack in it too.

I was quoted £700 to change the sensor and gaskets….would have been £1,100 with the cover. This was via an ind. The genuine sensor was £325, gasket set £46 and the rest labour.

I tackled it myself. I bought a VDO sensor for £175 (BM part number ground off), a Febi cover for £200 and something but stuck with BMW gaskets. I also replaced the spark plug tubes.
 

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Discussion Starter · #9 ·
My 130i had a slight weep from the rocker cover and an eccentric shaft sensor with oil in he connection. I racked the changes myself and discovered that the rocker cover had a crack in it too.

I was quoted £700 to change the sensor and gaskets….would have been £1,100 with the cover. This was via an ind. The genuine sensor was £325, gasket set £46 and the rest labour.

I tackled it myself. I bought a VDO sensor for £175 (BM part number ground off), a Febi cover for £200 and something but stuck with BMW gaskets. I also replaced the spark plug tubes.
It sounds like there’s definitely cheaper alternatives as long as you stick with OEM gaskets. Well im tempted to get a second opinion on the misfire to be honest as like some others have said oil in the spark well doesn’t necessarily equals misfire. The indy only recommended new sparks and coils this after doing some diagnostics. I do find it odd that its only noticeable a bit on idle. I’ve literally checked everything and the only other two things i can conclude are dodgy solenoids or injectors, and a slight chance that a valvetronic motor leak could cause a misfire.
 

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I just want to chime in and say I replaced my entire valve cover, I am very glad I did. Because old one was absolutely shagged, clearly had been repaired internally before as well.

I did not use a genuine cover. I bought one on eBay for a smidge under £100 new, which included the gaskets. Which is annoying as I'd already purchased a Febi gasket kit.

Fitment was OK for the cover. Had to realign a bit more than I expected to but it's been sealed up tight for well over 2000 miles.

I will say that it was an absolute pain in the ass to get the clearance to take the covers in and out.
 

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Discussion Starter · #11 ·
I just want to chime in and say I replaced my entire valve cover, I am very glad I did. Because old one was absolutely shagged, clearly had been repaired internally before as well.

I did not use a genuine cover. I bought one on eBay for a smidge under £100 new, which included the gaskets. Which is annoying as I'd already purchased a Febi gasket kit.

Fitment was OK for the cover. Had to realign a bit more than I expected to but it's been sealed up tight for well over 2000 miles.

I will say that it was an absolute pain in the ass to get the clearance to take the covers in and out.
Did you have any dodgy idle or performance issues or just a few leaks. It is odd how some have advised oil in spark wells isnt good and some say to not worry too much about it unless theres loads. Just an observation, ive come back from holiday and drove a short distance and it felt more lively after being sat for a while. It has done this before and i always wonder why it does this.
 

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I had many little leaks and one major leak that caused the car to be undrivable, because when you idled at traffic lights or something it'd smoke so bad even through the vents etc.

I do still have a very occasional wonky idle that lasts for about 5 secs. This hasn't changed before or after the cover change. It rarely happens at all though.
 

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Discussion Starter · #13 ·
I had many little leaks and one major leak that caused the car to be undrivable, because when you idled at traffic lights or something it'd smoke so bad even through the vents etc.

I do still have a very occasional wonky idle that lasts for about 5 secs. This hasn't changed before or after the cover change. It rarely happens at all though.
Thankfully have nothing as drastic as that on mine but im definitely feeling a lumpier idle at times especially on cool mornings. I have it booked into my indy to have the gasket replaced along with sparks but im wondering if its worth getting him to do a compression test at the same time just incase theres a deeper problem with pistons/valve stems etc.
 

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Thankfully have nothing as drastic as that on mine but im definitely feeling a lumpier idle at times especially on cool mornings. I have it booked into my indy to have the gasket replaced along with sparks but im wondering if its worth getting him to do a compression test at the same time just incase theres a deeper problem with pistons/valve stems etc.
Get the compression test done, peace of mind and make sure he does it as the first thing on the list! I'd be very surprised if there is an issue though.
 

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Discussion Starter · #15 ·
Get the compression test done, peace of mind and make sure he does it as the first thing on the list! I'd be very surprised if there is an issue though.
Just a thought. Making sure im going down the right route regarding the cause of the misfire -what are the chances this may be down to the fuel injector. The signs point to sparks and gasket but whats the usual signs of these failing on an N52. I know theyre not prone to fail but am just ruling everything out.
 

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the N52 after 2006 has PCV valve integrated in valve cover and when this PCV valve is not working the oil is pushed thru various weak places and there are many oil leaks.
So if you didn't changed this cover, or you see that is wasn't changed before, then you will have continious oil leaks until you swap cover. I'm not sure if aftermarket (non-bmw ) covers have good PCV implementation.
 

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Discussion Starter · #17 ·
I got the rocker cover gasket replaced in the end along with plugs and coils. The indy i used was happy with the condition of the engine cover. Car is running a little better along with better fuel consumption but do still get slight rough running in the mornings on a cold start. Have checked for signs of blocked breather system etc and everything seens ok. Ill just have to wait for it to get worse i guess as nothing obvious is jumping out.
 
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