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Leaking oil from filler cap

mhgreen

mhgreen

Member
Joined
Jan 8, 2015
Location
Portland, OR
'89 240, automatic .

oil leaking from around the filler cap.

filler cap seal, front engine seals, and valve cover gasket have all been recently replaced. PCV system is clean. opening up the cap while running gets a lil messy - definitely some pressure. oil dip stick remains in place.

running well, no smoke or any drivability issues. apparently not losing enough oil to leave any spots underneath.

main concern is should i be concerned?
 
Hi,
Did EXACTLY all that, also running fine (91 245 b230F)... ended up with thin-ish piece of cloth rag around the oil filler neck.
Weird, but completely dry ever since. rgds
 
opening up the cap while running gets a lil messy
Click to expand...

note that there is a cam lobe right there so it will always fling some oil regardless of pressure.

if you loosen the cap and set it down, does it suck to the valve cover (negative pressure) or get pushed off (positive?)

my car has been leaking a little bit from there since I bought it. it's never been a big issue but it never looks good.
 
Khrrck said:
note that there is a cam lobe right there so it will always fling some oil regardless of pressure.

if you loosen the cap and set it down, does it suck to the valve cover (negative pressure) or get pushed off (positive?)

my car has been leaking a little bit from there since I bought it. it's never been a big issue but it never looks good.
Click to expand...


positive pressure. inflates da glove / nearly tosses a loose cap off
 
* when i say PCV system clean i mean flame trap. haven't looked at the breather box.

Series of events .... leaking oil up top - - replaced cap gasket and valve cover gasket . THEN .... leaking up front - - replaced front seals. Now pushing through the filler cap . HAS TO BE too much positive crank case pressure yes? seems to be finding the path of least resistance?
 
one thing i've noticed is that while idling the filler cap dances around when loose, but if i open the throttle it stops the dance. moreover, if i disconnect the vacuum hose from the pcv system at the intake hose, there is no discernible change. I assumed the engine would stutter a bit ?
 
The hose from the flame trap to the intake air hose can clog with chunks of pcv goop. The port in the intake manifold can clog from the same goop. You can probe it with a piece of wire. Of course the breather box drain hose can clog and cause oil leaks and seepage around the breather box.
 
yeah i already took a paper clip to the manifold nipple & pcv -> intake hose is clear. i'm not a mechanic, and i've only ever worked on my 240s. trying to better understand the mechanics of the engine - particularly as it relates to pressure. i assumed when i replaced the filler cap seal that i would be all good. i didn't realize that the issue was potentially bigger than that until i noticed the oil getting pushed pass that new seal.
 
Seems to me, definitely a clog somewhere in the pcv, flame trap, or oil separator lines. All three of my Volvos were clogged when I bought them. 244, S90, and now 850. The recent 850 is passable with a flame trap removal. No oil leaks from the oil filler gasket any longer. Either you have serious blow-by from the pistons (highly doubt it), or a hidden clog somewhere in a hose, or engine block entrance/ exit somewhere.
 
I bet your oil separator box is full of junk. You don't need to be a mechanic to get to it, it's pretty straight forward to do, even without removing the intake. Use a long screwdriver or other scraper device to break up the stuff inside and shake it out into the trash. Check all the PCV lines as well, they get the same gunk stuck in them.
 
The oil drain hose from the PCV box back down to the sump clogs up with goop. I can practically guarantee that hose is clogged. Especially if your engine is running regular oil and not synthetic.
 
ok ok. thanks for the thoughts . sometimes it's nice to just get a group of people helping point me in a direction before going further. breather box needs attention. i'll check it out, & report back 🤘
 
breather box all gooped up. got the new OE on there. PCV system now all good. i'm hoping that solves the problem of the oil sneaking past the cap. we will see.
 
just ran the car around town / did some freeway driving & happy to report no evidence of leaking at the cap! thank you all!
 
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