I know I’m kinda the odd-man out here at times due to the boats age and the fact we have Ford based PCM engines. So here’s my head scratcher. I picked up a decent manual vacuum pump to draw through the dipstick, when I used it I only pulled about 1.5-2 quarts out. Now the ‘76 PCM 351W has what pretty much seems to be a center sump, I read something about it that they did that so no matter what pitch/roll or plane you were on the pickup would always have oil. The tube is actually not in line with the sump though it’s closer to the front of the engine on the right side. So I’m thinking when that hose is bottoming out it’s just hitting high up in the pan and I’m really not getting it out. There’s 2 cut marks on the stick that pretty much correspond when I added back in 2 quarts 1 by 1, bottom line showed 1st quart then top line for the 2nd. HOWEVER there is another line a good inch or more higher up. Not knowing what’s actually in there I don’t want to go for broke and just overfill it to that higher line “assuming” that’s the fill line. They obviously didn’t come with the fancy drain tubes everybody has now, NOR did they come with any room to place a pan under the engine let alone get down to it…. Just wondering if anyone else has had success getting these engines fully drained with a vacuum system. My thought was to just sacrifice the 2 quarts I added, suck them out, squeeze my way down there with a shallow disposable pan, try to pull the plug and then suck out whatever ends up in the pan before trying to get it out. Then add a drain kit and not change it again until she’s hauled out for the winter!!!!
Yes I do know it works, we tried it on the neighbors 5.7 and it pulled well over 4 quarts out so I know it’s not the pump.