360 rear seal revisited-possible cause...I need the experts!!!

OK recently posted about the rear seal I'm about to replace due to an oil leak. I've noticed a mechanism that seem to be causing the oil leak.
seem the rear seal doesn't directly leak when the engine is running or if it is its very little. I noticed after changing the engine diapers that they stay clean until i turn the engine off, then, after a few seconds, I get a small trickle of oil out of the seal. Friday the engine was topped up with oil after a day of fishing with many starts and stops I returned to the dock a qt. low. engine diaper was soaked. So today I inspected the engine and a friend who knows a ton about 360's listened to my symptoms and asked how the PCV valve looked. I pulled it and noticed that it was not connected in the proper way, with the hose run to a point of vacuum( his draw vacuum from the manifold, my starboard draws from the base of its carb.) this engine had the PCV hose connected to the flame arrestor and not very tightly( large gap). No possible way this setup provides any vacuum to the hose, let alone enough to operate the valve.

Ok next problem, my carb doesn't have a vacuum port to connect to.

My mechanic wrangled a pair of carbs from a set of engined bound for the junk heap, only issue is they are from a crusader 350's ( which is a big block), he said the only real difference is the needle valve size. which I assume we could swap from my existing carb??
These "test carbs" do not have a nipple for the fuel dump hose from the fuel pump but the do have a plug where it should go.( i can use the one from my carb)

Our next step is to get the PCV system operational. in the hopes that the excessive crank case pressure caused by a non functional PCV system is causing the leak.

I've read from several sourced that a bad PCV system can cause oil leaks much like the one i'm having.

Does anyone have an idea if this diagnostic makes any sense??

Greg-

If the PCV valve is closed, there is no relief for any of the blow by in the motor co the crankcase willl become pressurized and push oil out of the seals.

murfman- i've changed the base plate of my carb to one with a PCV port, and connected to the PCV valve. fingers crossed this helps keep some of the oil in the pan.

my engine now follows this diagram

.."If the PCV valve is closed, there is no relief for any of the blow by in the motor co the crankcase will become pressurized and push oil out of the seals. "

Right! And marine engines MUST have a functioning PCV system since they run relatively cold in a moist environment.

Jeff

So maybe just matbe this will help my leaky seal issue or at least will not hurt it!!!
Engine idles better already!!!!

Originally Posted by westiemax
after 1 1/2 seasons...the oil leak is fixed...and i cant believe the cause...As you all know sometimes the bilge area is very tight and tracking leaks is difficult. I thought i might be on to the cause with the PCV system. after changing the carb base to connect the pcv valve to vacuum, still leaking...frustrated i took my cell phone and with the light on i videoed the entire lower section of the engine. allowing a look into areas the i could not see directly!!! I review the footage on the phone and it made me visibly upset. BUT it wasn't until i looked at it on the computer screen the i realized where the leak was coming from.----

as some of you know Chrysler marine uses an adapter to change the position of the oil filter and to rotate it 90 degrees, thus allowing the dipstick to be positioned where the filter would normally be... and since the filter blocks the direct view i could never see the leak.

all my oil was leaking from the adapter plate. item # 6 was the original paper type gasket and was shot, leaking down the pan edge and was looking like it was coming from the rear bottom of the engine.

$18 part fixed at least a years worth of issues...

The bottom line- video saved the day.

Thanks to all those who helped me work through this issue.

Smart sleuthing and a good fix!

Jeff

Thanks Jeff!! Modern tech to the rescue.!!! Next task is to figure out why my economy has taken a dip since i got the PCV system working? I have an idea but its just a guess. I'm thinking now that the crankcase by products are being introduced to the combustion mixture is not a potent as without and thus takes a bit more fuel to get the same bang? Just an idea. Also notice that engines now burn almost the exact same amount per hour.( they didnt begfore)
strange thing too is i used to have to offset the tach's as in port motor exact 3000 rpm's ,I needed to push startboard up to 3200 ish to get them in sync( the kinda sync you can hear and feel as they become synchronous.) the starboard had a functioning PCV the port did not. Now it seems i no longer have to do this the tachs read exactly the same and they sound in sync. strange. My head says if the sound in sync they must be in sync( rpm matched) but if they are turning different revs they cant be in sync? Now my head hurts from all this. oh boy, fix one thing find two more.