E46 vacuum question

E46 vacuum question

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STW2010

Original Poster:

5,714 posts

161 months

Monday 5th January 2015
quotequote all
I have an odd issue with my e46 330.

About a year ago I diagnosed a faulty CVV and so changed it and all of the pipes. The cam cover and oil filter gaskets were leaking, so I changed these too. Now the car is using oil (about 1 litre per 800-1000 miles, which is surprisingly 'ok' for these engines), however it isn't using oil, it appears to be losing it.

The symptoms-
1. Oil spray around the filler cap
2. Cam cover gasket is leaking (again)

However there is a change in the engine note when the oil filler cap is removed and air is being sucked in (even more so when I press the accelerator)- this is, to my understanding, a sign that the CVV is in fact ok.

So, there is a vacuum yet still oil spray is being pushed out of the filler cap. I can't work this out. The behaviour of the oil suggests a blocked breather somewhere, yet all other signs suggest that the CVV is ok and the crank breather pipe is clear too.

Any ideas anyone?


mark.c

1,090 posts

179 months

Monday 5th January 2015
quotequote all
This may seem like a daft question and apologies if it is but first things first, are you checking the oil level correctly and not overfilling it ?

IE, IAW with the handbook ( normal operating temp, wait a few mins etc) ?

STW2010

Original Poster:

5,714 posts

161 months

Monday 5th January 2015
quotequote all
Not a daft question. You have made me doubt myself though! I'll check this.

Edit- just checked and oil is definitely within the min/max lines. Definitely made me doubt myself there though- fortunately my brain cells haven't escaped yet

Edited by STW2010 on Monday 5th January 13:00

ftypical

457 posts

117 months

Monday 5th January 2015
quotequote all
Blown piston rings pressurising the crankcase and forcing oil past the filler cap and cam cover seals.

kev b

2,708 posts

165 months

Monday 5th January 2015
quotequote all
You need to do the "rubber glove" test, (You tube/Google) to see if you still have a problem with the breather system.

A mate had an CCV problem on his 320Ci, oil consumption went from 200 miles/litre to virtually nil when repaired.

STW2010

Original Poster:

5,714 posts

161 months

Tuesday 6th January 2015
quotequote all
ftypical said:
Blown piston rings pressurising the crankcase and forcing oil past the filler cap and cam cover seals.
How sure are you of that?

buggalugs

9,243 posts

236 months

Tuesday 6th January 2015
quotequote all
STW2010 said:
ftypical said:
Blown piston rings pressurising the crankcase and forcing oil past the filler cap and cam cover seals.
How sure are you of that?
I think you'd be using a lot more than 1l/1000 miles if the rings were that knackered!

STW2010

Original Poster:

5,714 posts

161 months

Tuesday 6th January 2015
quotequote all
There would also be blue smoke wouldn't there? The exhaust is definitely normal, plus I have followed the car with my wife driving (she does enjoy a straight line blast) so I would have seen blue smoke if it only happens under load too.

ftypical

457 posts

117 months

Tuesday 6th January 2015
quotequote all
STW2010 said:
How sure are you of that?
That you have positive pressure in the cam cover says it isn't a CCV/inlet manifold problem. The cylinders are the number one source for this.

But yes, based on previous experience, I would expect a lot of oil loss/usage if the oil scrapers have failed on even one cylinder.

Maybe the oil return passages in the crankcase are blocked?

kev b

2,708 posts

165 months

Tuesday 6th January 2015
quotequote all
The amount of carbon deposit that can build up in a neglected BMW six is surprising, are you sure it was all removed when the piping was renewed?


STW2010

Original Poster:

5,714 posts

161 months

Wednesday 7th January 2015
quotequote all
Remember the oil volume going down is a mixture of loss and use, so topping the oil up isn't a major worry (about £10-15 a month on oil, which I can live with having previously had an RX8!). So I reckon we can cross off the piston rings for now.

I need to research how the oil and the separator work, and truly understand how the whole lot work.

One job I am considering doing to hopefully resolve this is taking everything off to access the CVV again, including the intake manifold. I didn't remove that last time as I was advised that it's a bh to put back on properly. That way I can really investigate the pipework, clean up the DISA and throttle etc.

I did vow never to do a CVV again. I did not enjoy.

Oh, and I just noticed last night that the water pump is leaking. That's the only component of the cooling system I haven't replaced. FFS!!


kev b

2,708 posts

165 months

Wednesday 7th January 2015
quotequote all
If you strip out the ccv again try and make sure the crusty carbon bits don't fall into the sump, they might block the oil pump strainer, use a hoover if possible.

I have seen the drain passage in the block totally obstructed when the pipe was removed, did you remove all the debris last time?

STW2010

Original Poster:

5,714 posts

161 months

Wednesday 7th January 2015
quotequote all
I don't think so, certainly not to that extent. Access is very difficult, so I pulled out the dipstick, connected up the CVV pipes and replaced it.

That might explain the problem...

In that case, at least it's not a matter of accessing the CVV again but just the sump/dipstick area (correct?).

ftypical

457 posts

117 months

Wednesday 7th January 2015
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Having replaced the CCV and pipes just before Christmas (blocked CCV, the return to the dipstick tube was dry, but the pipes to the inlet manifold were dripping oil when removed), there appear to be several ways to do it that minimise the swearing without the need to remove the inlet manifold.

The 3-part BavarianAutos YouTube guide is a good starting point, noting that you don't need to bend the dipstick tube - just remove the retaining bolt and it will rotate out of the way, and that removing the throttle body makes access easier.

The CCV runs on inlet manifold vacuum though, so it can never pressurise the cam cover, let alone force oil past the cap or the gasket.

HTH

ftypical

457 posts

117 months

Wednesday 7th January 2015
quotequote all
One other thing you could check, given that both the oil and cooling systems are leaking: test for oil or exhaust products in the coolant header tank.

STW2010

Original Poster:

5,714 posts

161 months

Wednesday 7th January 2015
quotequote all
ftypical said:
One other thing you could check, given that both the oil and cooling systems are leaking: test for oil or exhaust products in the coolant header tank.
eek Are you guys trying to scare the st out of me?

The headgasket is fine- I have changed the coolant recently as part of my pre-winter servicing. Also, there is no gunk under the filler cap whatsoever. The coolant loss is exceptionally minimal- I only noticed it by chance and the level in the header tank was still ok.



Edited by STW2010 on Wednesday 7th January 19:01

STW2010

Original Poster:

5,714 posts

161 months

Wednesday 7th January 2015
quotequote all
Also, I removed the dipstick entirely. I remember checking that the o-ring was in place before popping it back in.

kev b

2,708 posts

165 months

Wednesday 7th January 2015
quotequote all
Where the hose from the bottom of the oil separator connects to the block to drain the oil back to the sump is probably blocked with "coke", letting the crankcase build up pressure and force oil into the inlet manifold to be burned.

Pull the pipe out and hoover out the carbon, in preference to poking it into the sump, this I would bet is the problem.

ftypical

457 posts

117 months

Wednesday 7th January 2015
quotequote all
I'm intrigued by this idea of carbon build up in the drain from the CCV. Sludge is possible I suppose, but soot?

STW2010

Original Poster:

5,714 posts

161 months

Wednesday 7th January 2015
quotequote all
I guess it depends how long it's been there, the heat it's exposed to and the compaction of it. It would probably resemble soot?

This sounds like it fits the problem. I shall investigate and report back.