Omega Owners Forum
Chat Area => General Car Chat => Topic started by: T.m.f on 29 October 2017, 15:16:17
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Had a look at 1 today 193k started engine ,slight misfire but cleared,opened bonnet and removed dipstick while still running,as it was removed it made a hissing sound and started to run rough,replaced it and ok again,did the oil cap and did the same thing,what could be the cause ?
I havnt brought it but if easy fix i might.
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Errr.......you’re interfering with the crankcase pressure?
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Pressure at the dipstick is likely a blocked pcv system I would guess. Never fixed on a Volvo but on Saab it's relatively common. Not hard to fix, just a messy job. That said, removing dipstick doesn't cause rough running on those, so could be a bigger issue :-\
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On every Petrol engined car I’ve owned, the engine either changes tone or stumbles when I’ve removed the oil filler cap. I wouldn’t worry unduly about it, esp as it’s ok with the cap on.
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I don't recall ever removing the dipstick with engine running on any car,so can't comment on that.As Stemo says removing oil filler cap with it running will alter how it runs.PCV system mentioned by jimmy944 is known to block up on these-especially on poorly maintained examples-most owners it seems just replace the whole lot with new items as opposed to cleaning them.About 1999/2000 they changed from cable throttle to "fly by wire" type.Electronic throttle module on the latter at least can play up but can usually fixed by BBA Reman.
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Blocked breathers normally identifiable by not affecting the idle rpm... That car sounds normal ;)