only smoking downhill

[Kgood]

I'm confused on my 37'. She runs fine uphill, on flats. She idles fine on flats and uphill. But if the truck is idling on a downhill slope, she outperforms a steam engine on the amount of cloud cover in the area. Appears to be oil, smells like it. Thought it was the oil bath but after checking the goose neck drain valve, its dry. Any thoughts would be appreciated

 

[TGP (IL)]

Sounds like worn valve guides.
They tend to leak on deceleration.
Worn rings will cause smoke under acceleration.
Tom

 

[mcmullag]

What he said. With the throttle plate closed, the intake stroke suction is pulling air past the valves, sucking air from the oil sump area.
On an overhead valve engine ohv you can sometimes get by with replacing the cup shaped rubber seals on the valve stems but on a flat head, I don't know what the valves have on them if anything to help stop this oil vapor from going down along the valve stems, or up, in this case.

 

[NDT]

I think your problem is related to the vacuum pump. Disconnect the line between it and the intake manifold and see what happens.

 

[armytruck63]

^and plug the port on the intake manifold, or else the engine will run like crap.

 

[T. Highway]

PCV valve has carbon buildup. Remove, disassemble and soak in thinner. Clean out the tube going to the rear of the engine while your at it.

Bert