volvo penta blowing oil out

[grafozz]

i had some trouble on arriving in greece from uk last summer, engine lost compression . took it apart to find valves on 1 cyl eaten away refurbished head ,new valves and ran sweetly but it is trying to blow oil out of the dipstick hole ! the bores were excellent ,piston was a little pitted , all looked good prior to re-assembly . the ex manifold was coked up but cleaned out before fitting . could it caused by a blocked/ restricted exhaust ? the breather was checked and cleaned too ?

 

[DickB]

I reckon the piston rings are letting gas through. That is the normal cause of blowing (from the oil filler)...

 

[VicS]

If you are absolutely certain that the breather is clear then it sounds like bore/ piston/ rings wear. It could also be a broken piston ring
You did stagger the ring gaps around the piston when reassembling didn't you. They should not be neatly lined up (or on the thrust side of the piston).

 

[pappaecho]

I would double check the engine breather. I have seen car engines which have had major work done on them because of "worn bore" " leaking valves" etc which were nothing more than a blocked breather

 

[Stemar]

If it's one of the 2001-2-3 engines, you can block the breather by putting the rocker box gasket on the wrong way round. I don't know if that applies to others, but worth a check, It'd be a cheap fix!

 

[VicS]

[ QUOTE ]
you can block the breather by putting the rocker box gasket on the wrong way round.

[/ QUOTE ] There is a small article and photo by Pat Manley on p 68 of the Feb PBO that describes that particular problem. It is a horribly small hole.

However grafozz says he has checked and cleaned the breather so presumably his is not one of the Volvo 2000 series.

Why do people ask questions about engines without saying what model it is?

 

[grafozz]

very sorry, its a volvo penta MD 2010 2CYL and i have cleaned the rocker box out and ensured the breather is clear even added another pipe to the original ,tapped hole in the cover am certain there is no scoring in the bores but maybe a ring has stuck ? compression test after top end work showed 300+psi (guage only went to 300)

 

[VicS]

Sorry not familiar with that engine.

300+ psi sounds reasonable but it might be good idea to measure them properly and compare with the worshop manual figure (Manual HERE if you don't have one)

You don't have the oil level too high do you?
I have had a (car engine ) breather completely blocked without oil being blown out via the dipstick although the same one did blow a load of oil out when I failed to fully insert the dipstick once. I had loads of oil blown out via the breather of a engine with a broken ring. Daft arrangement 'cos it blew it into the air filter which became saturated, making the engine run seriously over rich (petrol, of course) so that I had to remove the element until I could sort it all out!