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Internal engine pressure

Specific discussion about the E89 2009 Z4 (sDrive35is, sDrive35i, sDrive30i, sDrive23i)
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mcbutler
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Location: Plymouth

Internal engine pressure

Post by mcbutler » Fri Oct 19, 2018 12:12 pm

Hi All,

23i 2009

I recently had my car to the local indy who told me that when they tried to remove the oil cap from the running engine it was difficult die to a negative pressure inside the crankcase.
They told me that the engine breather is integral to the cam cover.
As a result they changed the cam cover which was quite expensive.
The other day while cleaning the engine I decided to start it and see if it was still hard to remove, it did 'suck on' a little bit but nothing major.

My question is, should internal engine pressure be positive/negative or the same as atmosphere??

Seems to me slightly positive considering combustion leakage etc..

Any ideas chaps??
Mark
Plymouth
E89
35i
Carmine Red
Black leather

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GuidoK
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Location: all over the place

Internal engine pressure

Post by GuidoK » Fri Oct 19, 2018 1:38 pm

Should be negative due to PCV.

If you want to know if the valve cover was changed for a legit reason: now way of telling now; the part is gone for a proper diagnose.
Z4 3.0i | ESS TS2+ | Quaife ATB LSD | Brembo/BMW performance BBK front/rear | Schrick FI cams | Schmiedmann headers+cats | fully polybushed | Vibra-technics engine mounts | H&R anti rollbars | KW V3 coilovers | Sachs Race Engineering clutch

Mister T
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Internal engine pressure

Post by Mister T » Fri Oct 19, 2018 3:33 pm

As above, slight negative pressure

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Smartbear
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Internal engine pressure

Post by Smartbear » Fri Oct 19, 2018 6:28 pm

Usually when the pcv is starting to go defective the car starts to burn more oil with sooty tailpipes etc, was your car exhibiting any of these symptoms? :?
Rob
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e89 Sdrive 20i, plenty of mumbo & good economy-the thinking bears z4
e89 Sdrive 30i, this ones busted, pass me another...
e85 3.0si sold

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