I saw it, but then forgot about it, sorry. Thanks for posting. How do I find if my valley pan is leaking?
The reality as I know it is . . . it's probably NOT leaking. There is no pressure there to make it leak, provided the pcv system is working and blowby is normal. Any oil that gets to the bottom of the valley pan is from splash which can get past the camshaft, which should be minimal.
The metal can erode, or eve crack in the middle from harmonic flexing, but still, no real pressure there to push the oil droplets out. Surely, they can coat the bottom of the metal and seep out probably.
There is always the concern that it a failed valley pan can pull oil into the intake ports if it erodes there. To me, the reality is that it would take a LOT of moisture to start the rust initially and more moisture to keep it progressing between the two pieces of clamped metal (intake manifold and cyl head). When such might happen, IF it happened on the bottom of the port, a vacuum leak on that cylinder would happen. Being on the bottom, might not show up with normal sprays of water or carb cleaner, which are applied from the top side.
If you put an aluminum intake against the metal valley pan gasket, with time, the bead in the metal gasket can wear away the aluminum on the manifold, resulting in a compromised sealing area. As the aluminum is softer than the metal. THAT can caused a leak which can be found from the topside of things. Which is why the one year the 440 6bbl intakes were aluminum, that Chrysler and later FelPro had an additional item in those particular gasket kits (I think FelPro put in all of their B/RB kits?) which amounted to the two paper gaskets for contact with the intake manifold side of the valley pan to prevent/greatly lessen such erosion of the aluminum by the metal valley pan gasket. An interface to let things move as the different expansion characteristics of the two metals happened with each hot/cold cycle.
So, IF you perceive you have a valley pan gasket leak, first thing to do is to check the torque for all of the intake manifold bolts. Not a lot of reason for them to get loose or back-off from the initial torque readings, but always check that FIRST.
When torqued, the clamping force is supposed to slightly flatten the beads on the gasket for a good seal, as the metal is softer than the cast iron it is sealing against. That seal is good enough to apparently please the Chrysler engineers as it has been that way since they introduced the RB/B engine in 1958.
I realize that almost every diagnostic tree for oi consumption lists the integrity of the valley pan gasket as a possible cause. Key word, to me, "possible", not "probable", normally.
For "valve jobs" and cyl head surfacing to cause a problem in this area, the heads would have had bo have been sut a good bit or even angle-milled. There are formulas of how much to cut the intake manifold mating surface to compensate for these things. Not normally in the realy of a normal valve job, I suspect.
If an engine builder decides to put a cast aluminum valley pan cover on, then soft intake-only gaskets would be needed. That can put a different dynamic on things, possibly.
I will say that these are what I have observed in my DFW/North Texas region and others in other parts of the world might have seen some different things happen. BTAIM
IF you suspect an intake leak, then get the FelPro gasket set and proceed with changing it. That way, you'll know all is well in that area. Any evidence of oil in the intake ports, near the gasket area, should be obvious, too.
Enjoy!
CBODY67
