Scott 70 Posted November 29, 2021 Share Posted November 29, 2021 Looking for some help on my 69 Mack R611. I'm having a lot of oil come out of the oil fill / lower breather tube. The top breather on the motor is clear and flowing good with very little or no oil. My air compressor is also getting some oil in the air system. What could cause my oil pan to build pressure? Thanks for any help. Scott Quote Link to comment https://www.bigmacktrucks.com/topic/68849-oil-blowing-back-out-of-oil-fill-lower-breather/ Share on other sites More sharing options...
Joey Mack Posted November 30, 2021 Share Posted November 30, 2021 my first thought is worn piston rings... how does it run? is it shaking? Quote Link to comment https://www.bigmacktrucks.com/topic/68849-oil-blowing-back-out-of-oil-fill-lower-breather/#findComment-483721 Share on other sites More sharing options...
doubleclutchinweasel Posted November 30, 2021 Share Posted November 30, 2021 Does sound like ring blow-by, at first thought. Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/68849-oil-blowing-back-out-of-oil-fill-lower-breather/#findComment-483744 Share on other sites More sharing options...
Freightrain Posted November 30, 2021 Share Posted November 30, 2021 Worn rings on motor and since the compressor is pumping oil it is also has worn rings. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/68849-oil-blowing-back-out-of-oil-fill-lower-breather/#findComment-483748 Share on other sites More sharing options...
Vmac3 Posted December 1, 2021 Share Posted December 1, 2021 I had a customer complaint of oil being pumped out of the breather on a 1996 Ch613. Air tanks had oil in them as well. After checking it out it ended up being the piston in the air compressor having a hole in it. V 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/68849-oil-blowing-back-out-of-oil-fill-lower-breather/#findComment-483834 Share on other sites More sharing options...
doubleclutchinweasel Posted December 1, 2021 Share Posted December 1, 2021 27 minutes ago, Vmac3 said: I had a customer complaint of oil being pumped out of the breather on a 1996 Ch613. Air tanks had oil in them as well. After checking it out it ended up being the piston in the air compressor having a hole in it. V Interesting. Pressurized air making its way to the oil pan through the hole in the compressor piston? 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/68849-oil-blowing-back-out-of-oil-fill-lower-breather/#findComment-483841 Share on other sites More sharing options...
Popular Post Joey Mack Posted December 1, 2021 Popular Post Share Posted December 1, 2021 well the bottom of the compressor has ports for the oil to drain back into the pan... Sounds feasible.. jojo 3 Quote Link to comment https://www.bigmacktrucks.com/topic/68849-oil-blowing-back-out-of-oil-fill-lower-breather/#findComment-483848 Share on other sites More sharing options...
mechohaulic Posted December 2, 2021 Share Posted December 2, 2021 take the discharge line off the compressor , lessening the compressor head pressure . run engine see if there's a difference in back pressure on oil fill. i would go with piston rings. not knowing engine history :hrs, mileage etc. have seen air compressors put pressure in pan ; not common. the pressure build up should lessen when air governor shuts air compressor off if it were the air compressor 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/68849-oil-blowing-back-out-of-oil-fill-lower-breather/#findComment-483874 Share on other sites More sharing options...
mechohaulic Posted December 2, 2021 Share Posted December 2, 2021 being a '69 the air system is fairly simple. a hole in compressor piston would also mean one slow building air system. other then draining coolant system , to pull compressor head isn't the worse project. if it's pumping oil into air tanks , you might consider changing it anyway. 2 Quote Link to comment https://www.bigmacktrucks.com/topic/68849-oil-blowing-back-out-of-oil-fill-lower-breather/#findComment-483877 Share on other sites More sharing options...
Scott 70 Posted December 3, 2021 Author Share Posted December 3, 2021 The truck runs normal. It is supposed to have newer rings. When I open the air on my tank and it goes down the oil stops leaking by 90%. The hole in the piston of the air compressor. Could be it. The compressor builds pressure normal and seems to work great though. But it appears that the compressor is putting air in the oil pan. Thanks you for the help so far! Quote Link to comment https://www.bigmacktrucks.com/topic/68849-oil-blowing-back-out-of-oil-fill-lower-breather/#findComment-484005 Share on other sites More sharing options...
Freightrain Posted December 4, 2021 Share Posted December 4, 2021 Worn rings in the compressor will put excessive pressure in the motor as it pumps(blowby just like a typical motor). Then lessens when the unloader opens. 1 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/68849-oil-blowing-back-out-of-oil-fill-lower-breather/#findComment-484061 Share on other sites More sharing options...
mowerman Posted December 4, 2021 Share Posted December 4, 2021 you might as well start with a rebuilt air compressor,,,your going to need it anyway....good luck..bob 2 Quote Link to comment https://www.bigmacktrucks.com/topic/68849-oil-blowing-back-out-of-oil-fill-lower-breather/#findComment-484071 Share on other sites More sharing options...
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