Marshallh_2007

I've got a 85 F150 4x4 Pickup with the flareside bed and wood boards. It's got the 5.0 V8 302 fuel injected motor with power locks and such, but bare interior. Project truck/daily driver, becoming less daily driver more project.

Main issues:
The most concerning issue I've experienced recently is that I'm hearing a knock coming from the engine bay. I've no experience delving that deep into my engine, so any advice or experience yall could share would ease my mind.

The knock is accompanied by an amount of smoke coming from the bay as well. My thinking is a gasket, either valve, or head gasket, has broken and is leaking oil on the exhaust manifold. I have noticed it does leak oil. That, or it its burning/smoking within the vale cover area, under the filler cap. On the drivers side valve cover, where the oil filler cap/PCV valve USED to be, I have installed an aftermarket breathing oil reservoir cap. I taped shut the inlet (from the PCV valve) on the air box that houses the air filter (the PCV valve was not sealed well at the box, and was shooting oil from the valve cover area into the air cleaner, a long with getting gunked up in the line) this is where I thought my engine troubles were beginning. I understand the use of the PCV valve for emissions control, but as far as the operations and whether it needs to be sealed within the air cleaner box like it was factory.

BLUF
Does the PCV system pressurize and require a tight seal? Is a breathing oil cap not advised for this engine? Is the PCV valve getting oil/dirty air running through it a sign of a further issue with the engine?

as far as my knock goes.. would removing the valve covers after cleaning the air intake system, show me the part of the system that I would need to diagnose the cylinder issue?

I am going to do a fuel filter replacement, oil change, trans fluid change, and fuel system treatment (sea foam most likely) for comedic effect and to check all the other boxes.

Steve83

The caption of this diagram explains what the PCV system does, and how it works:


(phone app link)

There are thousands of noises that might be described as "knock", but very few of them are caused by anything under the valve covers. Most are in the crankcase, and require a full rebuild, or replacement engine.


(phone app link)

This site may interest you:
http://www.garysgaragemahal.com/

NZCOBRA

Hi , the pcv, positive crankcase ventilation, valve also it supplies a percentage of idle air , I think there was a ford mod as it's vacuum source was was causing problems with number 8 cyl . Move it to central vac tee . Get a new one , some of these can be noisy and pass too much air . Breather on drivers valve cover pcv on the other . Cheers

NZCOBRA

If your engine is getting really worn , lots of blowby, then excessive oil in the chambers will lower your octane and cause the onset of knock sooner . Cheers