pvc valve location and testing?? (1 Viewer)

[genesimmons]

hi all. is there a relatively easy way to test a pcv valve and what are the symptoms of a bad or failing valve? my 78 is expeirinecing oil consumption but no visible sign of blue smoke. could that be a sign? is the valve an easy swap/location. thanx in advance.

 

[Grayscale]

You should do an inspection of the valve. The location varies on the pushrod cover, but, it is there. I think that the manuals suggest cleaning them in solvent. A PCV valve is a flame-arrestor as well as emissions equipment, so must close when pressured from the intake side (backfire). It normally has vacuum on the intake side, so it needs to have proper OEM vac function. I don't know how to perform a bench test with any PCV valve to say yes, no, or maybe. I run it as long as it isn't pitted with rust, the spring isn't broken (had that on a brand new OEM one) and, that it is clean. Also, look for foamy oil.

 

[Living in the Past]

PCV positive crankcase ventilation was around long before emissions were started on the FJ40. Whole idea is to prevent gas fumes from building up in the crankcase from blow by on the rings. Right mix of gas fumes and air in the crankcase case and enough hot gas leaks by when ignited by the spark could end up in an explosion in the crankcase. The PCV is really just a check valve. Should always be a flow into the intake manifold. You do have a tube running from the air cleaner to the vavke cover? If not could cause the crankcase to be negative pressure. With the correct flow it shouldn't be pulling oil from the crankcase. Would think excessive blow by would show noticeable smoke at idle.

 

[B y r o n]

They aren't that expensive so picking up a new one is easy insurance. In the old days, testing was as simple as shacking it. If it rattled the valve/piston was free and working. If you didn't hear anything it was gummed up and needed to be cleaned or replaced.

 

[Green Bean]

This is the OEM one we recently got from Toyota for our 1970:
PCV Valve 12204-61010

 

[Living in the Past]

I remember a deer hunt that my friend's 77 FJ40 experienced his 2F having an oil consumption issue. We were miles away from camp and engine was getting noisy. Oil was very low. Hitched a ride to camp and I towed back to camp with my 68 FJ40. Solved the problem by adjusting the valves. Think it was an exhaust valve that was way out of adjustment but not sure. This was either 1984 or 1985. New PCV doesn't solve the problem worth checking the valves. If you have tool to check cylinder compression would probably show up. Didn't have that but I always carry feeler gauges.

 

[genesimmons]

I remember a deer hunt that my friend's 77 FJ40 experienced his 2F having an oil consumption issue. We were miles away from camp and engine was getting noisy. Oil was very low. Hitched a ride to camp and I towed back to camp with my 68 FJ40. Solved the problem by adjusting the valves. Think it was an exhaust valve that was way out of adjustment but not sure. This was either 1984 or 1985. New PCV doesn't solve the problem worth checking the valves. If you have tool to check cylinder compression would probably show up. Didn't have that but I always carry feeler gauges.

checking the compression is on my list to do, i also want to check/adjust the valves, i can smell oil buring but cant see anything. the engine seems to run well and has good oil pressure.