[Dormermike]

Hi

Very slight puff of blue smoke from an n53 engine but only occasionally. Seems to be if it's been driven hard the day before. If left to idle for a while then revved there is a slight hint of blue too. Is not over filled.

Valve stem seals seems most likely? Or could it be CCV related ? Sub 50k so not great to see. Is under bmw monthly warranty but difficult to see them paying out as it's not broke as such.

Thanks

[abeardo83]

Have you checked out your PCV valve? If it gets clogged, you'll get blue smoke.

[Dormermike]

Thanks - where is it? There is a wierd humming noise when it's hot which goes when the oil cap lifted, I think it's the separator in the valve cover.

[Phil325i]

For interest see this:

https://vanos-bmw.com/valve-cover-n5...mw-11127552281

Says it's applicable to N53, but I think the design of the N53 valve cover is rather different than the N52. You could also think about fitting an oil catch can and even partially blanking your EGR, as they both help cut down the amount of cr*p getting into the PCV system and hence into your cylinders...

[Dormermike]

Where is the EGR?

Car is under mondial warranty but I doubt they'll care about the odd puff of blue smoke.

[Phil325i]

Originally Posted by Dormermike

Where is the EGR?

Sits under the inlet manifold as I recall. See here:

http://www.realoem.com/bmw/enUS/show...diagId=11_3974

It takes hot air from the exhaust manifold, round the back of the engine and into the inlet side. I put my partial blanking plate at the point shown as '6' on the diagram.

[Dormermike]

Thanks

Trying to understand why a clogged PCV would cause oil to enter combustion chamber and blue smoke ?

[Dormermike]

Originally Posted by abeardo83

Have you checked out your PCV valve? If it gets clogged, you'll get blue smoke.

You sure about that? Obviously easier than valve stem seals being knackered but I can't see how a clogged pcv can cause oil to get into combustion process?

[abeardo83]

Originally Posted by Dormermike

You sure about that? Obviously easier than valve stem seals being knackered but I can't see how a clogged pcv can cause oil to get into combustion process?

A bad PCV valve may have a leak, which will cause excessive oil consumption. This is because the pressure in the crankcase may increase when the PCV valve fails, so the oil is pushed out through the seals and gaskets as its not allowed to escape any other way.

[Dormermike]

Yeah pretty sure it's not that. Got a vacuum at the oil filler cap. Think it's valve stem seals. Pretty poor for 40k

[Dormermike]

Anyone know if valve seals are a weak spot on these engines ?

[old grey steve]

Seen a couple of N53's with this sort of issue unlike the earlier N52 where the breather was external thus more straightforward to work with the N53 set up seems to be a slightly more headscrstching one to wok with, but we've replaced a couple of rocker covers on these with the same issue to find the problem of the integral breather breaking down was proven to be the right and correct move to take. But you've got to box a bit cleaver rev these as it could prove to be something else(we've done countless Mini R56's too which have the basic same integral valve cover breather set up (though some Mini's also have an integral breather within the inlet meaning both have to be replaced at the same time due to the parts being modified and needing to be replaced in some cases as a balanced pair)and largely it proved again to be the right and correct move to solve the issue) but we've seen a couple of Mini's where things improved only to again show the same symptoms later on.

So to answer a valve stem question? On these we haven't seen any but that's not to say that a modern engine like this couldn't suffer from such an issue. But as you'd of maybe concluded the same sort of symptoms re blue smoke from the tailpipe when blipping the throttle on tick over after letting the car idle for say 30 seconds plus or when pulling away after say sitting at a set of traffic lights can be down to stem seals as well as the breather which makes it mighty difficult to pinpoint exactly what the route cause is

I'd say you'll need to find someone with some decent BMW knowledge/open mind to help you move forward when we've seen this sort of issue we hsve replaced the rocker and as stated its proven to be the right fix...... But in these you never know as various issues are staring to emerge

[Dormermike]

Thanks Steve was hoping you'd see my question

When I pulled the plugs out recently I did see a small bit oil on one of the plugs threads which suggested to me cam cover leak but the plug bores are spotless.

I'll check again, plug 3 I think it was.

Engine under mondial warranty but can see it being a convoluted game of back and forth with a BMW dealer as they rarely have the diagnostic skills or energy in my experience...

Thanks

[old grey steve]

Originally Posted by Dormermike

Thanks Steve was hoping you'd see my question

When I pulled the plugs out recently I did see a small bit oil on one of the plugs threads which suggested to me cam cover leak but the plug bores are spotless.

I'll check again, plug 3 I think it was.

Engine under mondial warranty but can see it being a convoluted game of back and forth with a BMW dealer as they rarely have the diagnostic skills or energy in my experience...

Thanks

Sometimes when you see oil in the plug wells it can/maybe down tohe smallest amount of oil being spliied on say a top up doesn't take much. On the N54's seen cracked rocker cover gaskets as you may be able to see from the picture below when nice and hot the crack simply opens




On the N54's the cracks appear to appear in the same place, leading to oil going down No2 No3 plug area

Pray your blue smoke isn't as bad as this 645i

[Dormermike]

Wow that v8 got a bad dose ! Mine not as bad as that and not every time either. It's an initial puff then clears. Most people wouldn't even notice I think. Does it after sat idle then revved which is all the hallmarks of stem seals but as you indicate it's breather system could account for the same issue.

Thanks for the crack pic. Entire area is spotless and clean as a whistle which is why the oil on the plug thread was so odd. Spilled oil makes sense but that was 1000's miles ago so would have burnt off by now.

[old grey steve]

Originally Posted by Dormermike

Wow that v8 got a bad dose ! Mine not as bad as that and not every time either. It's an initial puff then clears. Most people wouldn't even notice I think. Does it after sat idle then revved which is all the hallmarks of stem seals but as you indicate it's breather system could account for the same issue.

Thanks for the crack pic. Entire area is spotless and clean as a whistle which is why the oil on the plug thread was so odd. Spilled oil makes sense but that was 1000's miles ago so would have burnt off by now.

THe 645i is quite common especially on 2004/05/06 cars you can easily relace the breather valve caps on these cars (£0 is for the pair) takes less than 1/2 hour and they sit on the rocker cover sand is a DIY job, then on these you simply hjave to re check oil level let the car go (as there will be oil emersed in the planet which needs time to clear) if the symptoms improve then you've got the problem on these cars solved the breathers on the V8's usually collapse and once removed its easy to see how they have fiared. On the valve stem seals more difficult on these of course but its common place on the V8's

Re yours again as I have said seen a few rockers suffer but have a read of this very detaild and a good read

http://diaryofanengineer2.azurewebsi...l-consumption/