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496 lost oil somewhere and spun bearing

Posted: Fri Jan 11, 2019 2:16 pm
by mudkat
I have a 20 x8 with a 496 with a rotator 2.68 and a S blade prop ,I've had tons of trouble with the motor from the start had a problem with the cam first time, I got that straightened out but this time it was running great but on 3rd trip out on the run back in it lost oil pressure and it spun a bearing. I checked the oil before I hit the water and it was less one quart low (9quart pan) I didn't have any oil with me so I thought oh well that's enough.
after I got home I checked and it only had 3 quarts left in it
My question is on the old 400 SBC I had in it I ran a PCV valve and never had any issues so I used it on this motor.
There is no leaks anywhere and the rings look good Could I've have lost the oil by getting sucked into the engine through the PVC?
Next time I'm going to just use some big breathers or a catch can with a breather on it
Has anyone had a similar problem of loosing a ton of oil pretty fast like I did ?

Re: 496 lost oil somewhere and spun bearing

Posted: Sat Jan 12, 2019 6:57 am
by dodobird
I wouldn't think if that many quarts of oil went thru the carb to the chambers would burn

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Re: 496 lost oil somewhere and spun bearing

Posted: Sun Jan 13, 2019 9:23 pm
by Aeon
Only a few ways for oil to get out. If you were burning it you would have seen blue smioke. 6 quarts in one trip would be obvious. Pcv is needed and does more good than harm. A oil catch can help a lot. On tear down your intake will have a ton of oil coating the inside.

Leaks can add up but that much would have oil on lots of places. The prop and radiator seem to catch the most

Only other place is for it to go into the coolant. That will be ckear when you drain it

Re: 496 lost oil somewhere and spun bearing

Posted: Mon Jan 14, 2019 8:07 pm
by mudkat
there was no oil in the coolant and there is no obvious leaks on the engine radiator or prop.
i was running it at night and had a pretty good run down the river running at 3800-4500 rpm. i’m kinda thinking it was only sucking the oil at high rpms and in the dark i wouldn’t be able to see any smoke

Re: 496 lost oil somewhere and spun bearing

Posted: Tue Jan 15, 2019 7:08 am
It is doubtful but one question would be how you have the valve installed. I run a positive crankcase ventilation system and have never pulled oil but my draw point is in a baffled breather that is designed for the purpose. If someone just pushed a PCV valve into a valve cover and that draw point has no baffle then your making such a scenario possible. That said it is still unlikely that 6 quarts would disappear in such a short time without you knowing it or some fouling of spark plugs.

If you take the PCV valve out and can see the rockers and springs you would need to get a push on breather with a location on the top to use as your draw point and push the PCV valve into it. Let us know how you have it rigged.