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[Markjay]

Firstly I would like to say that I understand the question and I don’t know the answer.

However – on my previous Omega, I had the breathers cleaned at 40k as pre-emptive measure, and my current Omega has done 50k and the cam covers are not leaking yet in spite of the fact that the breathers haven’t been cleaned so far.

I guess that this shows that if you do clean the breathers properly and change the oil regularly then the gaskets should be good for the next 40k-50k easily…

So as a theoretical issue this may be interesting, but from the practical point of view I find the disptick trick – even if it does work, which may very well be the case  – pointless…

[Andy B]

Now ..... play nicely!!  

[spiketheskinnydog]

Well, if you already you know the answer, not much point in asking the question

Leave him alone STMO he was only asking for confirmation and now has Laidback scratching his head - that doesn't happen often

I have no problems at all with the content, just way it is written

  again

   Q. Has BoBo nicked your smiley?  

He will return, bigger and smilier, after the "festive" season

Thanks for that most valuable help STMO. Your comments fully answered the query!  

Actually, I took exception to your comments regarding your opinions as to the value of highly trained mechanics. I feel that I am reasonably proficient with most mechanical issues, but there is no doubt that someone with years of training would be on a totally different level. In fact, my brother's training took longer than my GP's, and I really wouldn't like to argue with him either. The point of my enquiry was to find whether anybody had any experience of this simple measure, not to get into some daft arguement. I am aware that there is quite a complex breather system on the Omega, including some sort of purge/pressurisation system on startup. I believed that leaving the dipstick poking out a little, so as to vent the crank to the atmosphere, may have some consequences on this, although I couldn't be sure what. Aren't questions such as these the reason why forums exist??


Anyway, I accept the reasoning from other users (that there should be no problems with cam cover seals blowing if the breather system is kept clear), which seems entirely sensible. My Omega's breather system has been fully cleaned when the seals were changed, but as its always had regular oil changes (as evidenced by the service history) I was suprised to see that they bunged up in the first place.

Perhaps use of a synthetic oil would improve matters, although I've heard that its not really good practice to use synthetic oil in a high milage vehicle that has always used mineral oils (My Omega's done 104,000, which seems bugger all to some of the Omegas I've seen though!). Any thoughts??

[TheBoy]

Absolutely



Not convinced myself about the dipstick thing, but good to see a debate over it

[STMO123]

Nuff said

PS. I didn't say ANYTHING about mechanics.

[Markjay]

... Anyway, I accept the reasoning from other users (that there should be no problems with cam cover seals blowing if the breather system is kept clear), which seems entirely sensible. My Omega's breather system has been fully cleaned when the seals were changed, but as its always had regular oil changes (as evidenced by the service history) I was suprised to see that they bunged up in the first place.

Perhaps use of a synthetic oil would improve matters, although I've heard that its not really good practice to use synthetic oil in a high milage vehicle that has always used mineral oils (My Omega's done 104,000, which seems bugger all to some of the Omegas I've seen though!). Any thoughts??

Just a couple of points about the oil issue…

There are two reasons why you could have problems if using synthetic oil after using mineral for a long period.

The first is that on older vehicles the seals rubber compound used to be chemically react with the mineral oil in such a way that if it was coming in touch with synthetic oil the rubber would start leaking – this should not be a problem with newer vehicles however where modern rubber compounds are used, but I don’t know for fact if this affects the Omega and if so up to what model year… At any rate the reason older engine start leaking when synthetic oils are first used ahs nothing to do with synthetic oils being ‘thinner’ and some people believe, because a 10W-40 synthetic oil will be just as thin as a 10W-40 semy-synth…

The second is that high-end synthetic oils have detergent additives and such can shift deposits previously untouched by lower-quality mineral oils. In this case, when changing from mineral to synthetic oil a second oil change after around 1,000 miles is recommended.

As for the fact that the breather on your car needed cleaning in spite of the fact that oil has been changed ‘regularly’, keep in  mind that most owners will service the car at best according to the manufactures recommended schedule – which are specified with fleets in mind where buyers want to be re-assured by low running costs. In the Omega’s case, changing the oil every 10k or 1 year on the earlier models or 20k 1 year on the later models as per Vauxhalls’ specifications, is no where near enough to keep the breather clean – the oil need to be changed every 3k-5k, but few owners actually do that hence the breather problem. The actual service interval depends on your driving style - city driving with short trips as opposed to long motorway drives etc.

[spiketheskinnydog]

Nuff said

PS. I didn't say ANYTHING about mechanics.

Haha! You're right! It was that "Laidback" person!! My mistake, sorry!

[Marks DTM Calib]

So.....my training here has not fully rubbed off on anybody yet then as nobody (including a ford master Mechanic ) has spotted the bleeding obvious.....

The crankcase is vented into the breather system and the fumes are carried to the inlet where they are burnt by the engine. In reality, most of these fumes are blow by gases i.e. exhaust fumes and as such are inert (no oxygen or fuel in them in theory....if all is working correctly).

Now, if you let air in (as well as fumes out) of the crank case system then you effectively create an airleak as air will enter the dipstick, pass through the crankcase, into the breathers (if they are clear) and into the inlet.....and this is unmetered air i.e. it has not passed throough the MAF.

This is likely to result in poor idle and the idel valve working at one end of its travel (more likely to stick).

So, in short....no.....fix the cause, dont just botch round it....

And yes, I am aware that tuned engines often vent to atmosphere (I used to vent the naff old Fiesta pushrod engines the same way because bore wear was so dam huge on them it resulted in the carbs getting clogged up in no time) but, this is much easier to do on a tuned carb engine or one running MAP control EFi....although I do seem to recall this being an MOT failure on post 90's built cars (could be wrong)

[spiketheskinnydog]

"The crankcase is vented into the breather system and the fumes are carried to the inlet where they are burnt by the engine. In reality, most of these fumes are blow by gases i.e. exhaust fumes and as such are inert (no oxygen or fuel in them in theory....if all is working correctly).

Now, if you let air in (as well as fumes out) of the crank case system then you effectively create an airleak as air will enter the dipstick, pass through the crankcase, into the breathers (if they are clear) and into the inlet.....and this is unmetered air i.e. it has not passed throough the MAF.

This is likely to result in poor idle and the idel valve working at one end of its travel (more likely to stick)."


Yeah, thats a good point! - One Carb  conversion coming up!

[Marks DTM Calib]

Actualy, this is a good post to learn from as many dont appreciate the air leak principle of air in the crankcase....

[spiketheskinnydog]

Yeah, there's certainly a lot to think about. I'd better stick my dipstick back in I suppose! Who'd have thought dipsticks could be so confusing!

[TheBoy]

Yeah, there's certainly a lot to think about. I'd better stick my dipstick back in I suppose! Who'd have thought dipsticks could be so confusing!

I work with a dipstick who is always confused.....

[Marks DTM Calib]

I looked at an Escort a few years ago with a poor idle......the seal on the oil filler had gone and it was very loose, air was getting in and buggering the idle up.

[familyman]

Just to show how engines are changing new supercharged Jaguar engines run negative not positve crankcase ventilation, if you dont push dipstick infully home the engine will run like a bag of s**t, right through the rev range.  I think venting to atmosphere on old tuned engine like pinto's was due to to multi carb set up 1 choke per cylinder on manifold and carb and balancing them with crankcase ventilation would prove very hard also the provision was not put on the inlet manifolds so as not to disrupt fuel swirl through them possible causing fuel to drop off in the manifold reducing power.
But as has been said due to maf sensors now days, adding air into an engine by another source (dipstick hole)would cause running problems.
Also oil is supposed to get dirty this proves its doing its job of collecting dirt and carbon from the engine, which is why replacing it and the filter is so impotant.

[STMO123]

Just to show how engines are changing new supercharged Jaguar engines run negative not positve crankcase ventilation, if you dont push dipstick infully home the engine will run like a bag of s**t, right through the rev range.  I think venting to atmosphere on old tuned engine like pinto's was due to to multi carb set up 1 choke per cylinder on manifold and carb and balancing them with crankcase ventilation would prove very hard also the provision was not put on the inlet manifolds so as not to disrupt fuel swirl through them possible causing fuel to drop off in the manifold reducing power.
But as has been said due to maf sensors now days, adding air into an engine by another source (dipstick hole)would cause running problems.
Also oil is supposed to get dirty this proves its doing its job of collecting dirt and carbon from the engine, which is why replacing it and the filter is so impotant.

Well, if your filter is impotent, try changing it!