Positive crankcase pressure?

[joethefish]

Hi all,
As promised in my hello post here is the first of what is sure to be lots of questions!
Secondly if this is a repost please forgive me, the laptop had a 'moment' when I clicked send originally and no idea if it went or not, either way I am sure the mods will put it right and dish out slapped wrists where appropriate! - Actually this version makes more sense!

Ok so I am looking for a new family estate/commuter/gear lugger and my first choice is a peugeot 406 probably in HDi flavor.

So today on route home I spotted one for sale, nice enough condition price is right and reasonable service history, 140k on it and last cam belt done at 98k. (Am planning on having to do one soon after purchase so no real issues there) Was a 02 reg 110 HDi estate.
However during my usual wander/nose/test drive of the car I noticed it looked like oil had been blowing out of the filler hole/under the filler cap, I took it off with the engine running and was greeted with some fairly significant pressure and a small puff of smoke (i think) at the moment I removed it pressure continued without any smoke and was noticably blowing out but not sucking in.. No smells other than the usual hot oil engine type smell but the pressure was significant enough to make refitting the cap need more concentration than expected, when I slipped with the cap trying to plop it on as normal it was blown clean off again. No blowing or sucking at all from the dipstick tube however.
So what am I likely looking at? (I have walked away for now but am willing to have a car needing some work as I am on a tight budget and even tighter timescale)
Is it liable to be blocked EGR or breathers or something more sinister like rings or valves?
Car drove fine from cold with no noticeable smoke from exhaust or dodgy noises. Biting point was a little high however.
Any info or pointers appreciated, like I said happy to stay walked away or equally go back for a second nose.. just wondering if my gut was correct or if these new fangled diesel things really are that different to anything I have played with before!

[joethefish]

No thoughts?
Anyone care to pop their own oil filler cap off and let me know what the see/feel?

Hopefully lined up a couple more cars to view over the weekend and dont want to discount things for the wrong reasons!

Thanks,
Joe

[lozz]

The small amount of smoke/vapour, from under oil cap with enging running couid be Normal id say,

if its was Spewing oil up then, no doubt somethings wrong, (Back preasure,)

ive noticed smoke/ vapour from a few of the 406s ive had, never had aproblem with them,
id just listen, for Top end noises, and look for Excessive plume of smoke from exhaust,

Sometimes ive found the Hdis can spit the Dipstick out, thats been down to the Engine cover mounts have Broken and fallen to bits, (Bad desighn)

[rlees85]

So on the HDIs is the only breather the one that goes from the cam cover to the air intake?

I guess there is no breather coming from the crank-case?

Just out of curiousity, as other cars I have owned have had 'PCV' filters that were prone to becomming blocked up.

[lozz]

Itook the oil cap off mine yesterday with the engine running,

there was some oil spitting up not alot but some,
and slight fumes/vapour,

my car needs oil change, so iexpect some vapours /fumes wouid be normal,.



Hth if any