Re: 35 Senior 8 Oil Loss

Posted by Tim Cole On 2011/11/16 18:42:19

Dear Classic Cruiser:

There are two possible sources and three possible causes of your oil leak at the back of the motor.

Oil pressure of 50psi will not cause this as I knew old timers years ago who set oil pressure so high as to inhibit horsepower. Throughout the 1930's Packard was increasing the oil pressure on the Senior motors because of results at the proving grounds. By 1939 the spec was 55-60 so that is what I would use as the upper bound for oil pressure using 30w oil. Packard issued service bulletins in the 1930's advising that insert bearing motors should be running higher oil pressures so lowering oil pressure is not a good idea. The SAE general rule for oil pressure is 10psi per 1000 of peak rpm. So for the Packard that translates to 45psi which is what a modern car would use. Higher oil pressure will use up some horsepower.

Now you said the path was clear for the slinger and so I assume that you have removed the oil pan and found the appropriate drain hole in the pan gasket. If the hole in the oil pan drain is blocked by a gasket it will throw oil all over the place.

Next are the wooden dowels in the rear main bearing. I used to mill those out of pine to .27 inches square. If they are not there oil will flow like a buffalo. Most machines shops don't know what they are looking at and throw them in the trash.

I also assume that the slinger end caps are on the motor as well. Don't laugh, I have seen any number of horrors as regards the slinger because motor workers just don't understand what they are looking at. At the back of the motor there should be two aluminum caps secured with eight special Packard fasteners that are tied together with bailing wire. I always used some sealer when assembling these pieces to prevent seepage.

Finally, there is a cam bearing on the back of the motor. That can leak os well. I once serviced a low mileage 426 sedan (1928) that was low mileage because oil was pouring out of that bearing. And that mistake was made by the Packard factory.

Hope this helps,