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Good afternoon: I am new to this forum and hope that I am posting this in an appropriate location? I have a 1986 F150 4.9L w/ 4-spd manual transmission with the odometer being broken I can only say it has at least 140K. I am trying slowly to restore this truck and replace mechanical issues one by one. After replacing the valve cover gasket, crankcase gasket, oil pan gasket & new oil pan along with many other parts (gas tank, radiator, alt, battery, etc.) I still have 1-2 ounces of oil that ends up in the air filter cover after running the truck (short or long distances). I've been told it has severe blow by due to rings going bad (GM mechanic vs Ford) and crankcase ventilation issue by a relative who has owned Ford's his whole life. I have installed a new PVC valve (rear of engine) and new carb as well as the valve filter cap (front of engine) that runs to the air filter cover, yet I still have to mop out the oil after each drive or it builds up to a
larger volume. Truck does have a smog pump with tons of vacuum lines running everywhere (been told its essentially disconnected) so I am wondering if the smaller vacuum lines may be clogged and need replacing. I would prefer to start with the simple items as I've spent considerable coin on the items I've already mentioned. Looking from help from anyone as I cannot find anyone locally who knows how to work on these older basic inline 6 engines. In advance, I appreciate any help and look forward to replies. Thank you!
No, the vacuum lines have nothing to do with it. Blow-by is the most common cause of oil being lifted from the valve cover into the air cleaner. But the entire PCV system must be working. Read this page (which applies equally to carbs):
But another possible cause is oil NOT flowing down from the head through the block to the pan, due to buildup in the drainback journals. I'd pull the fuel line & valve cover (taking the opportunity to replace that cork gasket with modern rubber), and bore-brush those journals. The engine will run without the valve cover (put the fuel line back), but oil may splash from the rockers, so I'd temporarily wrap each one with Aluminum foil so the oil drips straight down. That will allow you to watch how the oil is flowing down through the journals, and check each exhaust valve guide for pressure leakage.
Steve83 Great information! Thank you so very much. I will, in deed, follow your advice. I had read older posts before becoming a member, but most threads I found were for 1987 years and up. I did replace the valve cover gasket, but with cork versus modern rubber which is also a great piece of advise. Thanks again I write a follow up post when I am able to dig into the items you mentioned and sort them out.
Steve83 thanks again!!! You are an absolute wealth of information. Truly appreciate the compression test link. Off subject: "Walk softly & carry a BIG SIX" has to be one of the coolest tag lines I've seen on this forum.
crankcase ventilation issues
