Smoke from engine bay

[Bob_telaylee]

Hi all, newbie here. My Z4 had a vague burning smell a couple times the last few days, then today after driving home (4 miles) I opened the hood to find this smoke coming from the engine bay [vimeo] https://vimeo.com/727506054[/vimeo]

Once it had settled down, it looks like here is the source of potential problems. [vimeo] https://vimeo.com/727506241[/vimeo]

I’ll take it to a good Indy garage tomorrow, but was hoping for advice on what you all thought the problem may be? What costs should I brace myself for?

Thanks in advance for any advice.

[B21]

Usually on the N20 engine it’s a failed cam box gasket or at worst a cracked cam box.

Due to the canted engine and the hot exhaust it’s usually looks worse than it is.

So it’s not a big job…you won’t know till you get the cam box cover off..then it’s cracked or warped it will be obvious.

You may get away with a fresh gasket if you are lucky.

[Jace71]

I had a similar issue the other week, found to be a small oil leak dropping on the exhaust from the rocker cover. Cost me 250 at my local garage with a rocker cover kit suppled from bmw.

[colb]

The cauise of the smoking engine bay is one of the most common faults that ocurr when our cars reach a certain age. The leaks of oil appear from the cam cover gasket as that goes hard with age and its sealing properties fail. The leaking oil drop down onto the hot exhaust and its heat shield causing it to burn and produce the smoke you see. The spark plug wells in the centre of the cam cover also have a set of gaskets that fail in the same way, when they do the wells fill with the leaking oil and drown the plugs causing running issues from misfires. It is also worth noting that some models have round sealing rubber washers under the cam cover retaining bolts, these should also be replaced when the main gaskets are replaced as they too go hard with age and will not compress to achieve the required torqued seal when its put back together. Quite important that the entire cover is airtight otherwise unmetered air will get in and mess up your fuel trims. Always worth cleaning the cam cover and closly inspecting for cracks in it as repeated heat cycles and age will degrade the plastic material the cover is made from, cracks in it will allow unmetered air in and cause fuel trim issues. A smoke test will usually pinpoint any cracks if you cant find them visually. When sourcing replacement gasket sets go for a set that includes the 15 round cover seals for the cover bolts if your car requires these. Pretty sure I used a Elring set from AutoDoc when I replace my E85 2.5 gaskets which included these seals with the main and centre plug well gaskets.
When fitting the main gasket ensure some gasket sealant is used only at the front and rear of the gasket where it changes direction over the half moon shapes and between the Vanos at the front and back of the cover. I use Blue Hylomar gasket sealant at these points, good enough for Rolls Royce area engines so good enough for our cars.
For E85 2.5 2003 Elring do this set https://www.autodoc.co.uk/elring/7625587
Another car I did we sourced the gasket and round bolt seals from BMW, Sophers at Lincoln and got a Forum discount.
I winced when I saw in an earlier post someone paid £250 to have theirs changed but most of that was obviously labour, at a guess it was for 2hours plus parts, thank goodness I can do this sort of job myself.

[Bob_telaylee]

So the Indy garage changed the cam cover gasket, but less than a month later and the same issue is back. Should I expect them to sort this free of charge? The labour charges made up the majority of the £300 I paid for them to fix the issue.

[B21]

So the Indy garage changed the cam cover gasket, but less than a month later and the same issue is back. Should I expect them to sort this free of charge? The labour charges made up the majority of the £300 I paid for them to fix the issue.

Often the cam box itself is warped and or cracked..that’s why often it’s best to change the gasket and cam box at the same time