I'm in the middle of trying to diagnose an oil leak. I think I've got it narrowed down to the breather valve on the valve cover (right next to the oil fill cap).

I've read every thread I can find about crankcase pressure and what can cause it, and of course I'm hoping I'm not looking at blow-by and the need for a rebuild.

My question is around the PCV setup. I've replaced the valve and confirmed it functions correctly.

This port (circled in red) is where the PCV valve connects. If everything was functioning correctly, should air be able to freely pass into this port?

If I were to blow into the hose that connects here - should air be able to pass into it without resistance? Or, is there a switch/diaphragm deeper inside the carb that opens to allow air in?

 

 

Thanks. Gives a good overview of the system.

My question is, should the path shown by the red arrow below flow unrestricted?

This is "downstream" from the PCV valve, where it enters the carb/throttle body.

On my truck, if I blow into that hose, I cannot put air through, it is completely blocked - making me question if there is a blockage in the port as it enters the carb/throttle body?




Thanks

 

Based on the FSM diagram, air should flow freely through that hose. Have you pulled the hose to see if it's clogged? If it isn't clogged, pull the air cleaner and look down the port the hose attaches to on the carb, to see if you can see a blockage.

 

Thanks. I was pretty sure that was the case, but wanted some reassurance.

I have confirmed that the hose is free of obstruction, but there is full blockage just inside the brass port on the carb. I'll have to pull the carb and see why it's blocked.

 

Just a suggestion but maybe first try to clear the port without pulling the carb. Run a vacuum cleaner to catch the bits while trying to remove the clog. Hopefully the clog doesn't extend down in the intake.