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Oil coming out cap, breather,...

TopBanana72

TopBanana72

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Hi all, I have noticed recently that oil leaks have developed around the cap and breather on the pass. side valve cover. Also seems to be coming out at the carb where the pcv line connects. Pcv valve is good (I changed it anyway, albeit with parts store quality). It's a high-mileage engine with about 50lbs oil pressure at cold start and about 8psi at hot idle. Any ideas?

1972 318 with edelbrock performer and Holley 4160.

thanks...
 
What kind of valve covers do you have? Is there a baffle under the pcv and breather cap. A old engine with lots of blow by has excessive crankcase pressure. It's tough to prevent leaks.
 
It's the stock valve covers, with the baffles. That sounds right, I was thinking there was something causing excessive crankcase pressure.
 
blow by ? had a friend with a chevy that did that on a high mileage motor
 
If you take the oil filler cap off, who much blow by do you have? Have you done a compression check?
 
Compression check ranged from 127 - 134. I have not looked at the engine running with cap off, or how to tell that way really. I'll do that though and see what it looks like.
 
TopBanana72 said:
Compression check ranged from 127 - 134. I have not looked at the engine running with cap off, or how to tell that way really. I'll do that though and see what it looks like.
Click to expand...
Hold some real thin paper over the PCV hole and see how hard the escaping pressure makes it flap around at different RPMs.
If oil's coming out at the PCV hose/carb connection, that's not a real good sign. Means oil is getting sucked into the intake tract. Are there baffles in the covers? How do the plugs look?
You say 'high mileage', and the oil pressure's a little low for hot idle....sounds like it might be time for a re-fresh.
In the meantime you might switch to a heavier oil like a 20-50 and see what that does for you. Not that it's a cure, but it might buy you some time...
 
Last edited:
I got this same problem on my 440 oil coming out the breather cap. Took my mopar performance covers of cause they leaked like a sive and put on stamped steel covers no leaks there now.
Still have oil blow by though through the breather on passenger side. Looks like I need to investigate also.
 
you have some serious bearing issues if you drop over 40lbs of oil pressure when warm.
8 psi is dangerous and i wouldnt even drive it on the road.
also,the blowby is more than likely the rings/taper of the worn bores,
sounds like the pass side,might have a cracked or worn badly ring.
might be a good idea to look for a replacement motor to swap in or plan a rebuild.

when you pull it apart look at the intake gaskets and see if they were leaking/sucking oil/oil stains.
 
well, I think you are all right.. .time for a refresh/rebuild. It's the original engine with 128K. I'm already running the thick oil which helped the pressure.

Now wheels are turning in my head what to do... rebuild 318?, swap to another engine?, modern hemi swap? so many choices, so little time :) I do know for sure I want to stay small block, the car is such a nice cruiser.
 
Yeah, sounds like rebuild time.
Staying with the LA engine negates the new "hemi".
Once you make a decision just for fun, put some "mechanic in a bottle" in the crankcase and see what happens. It might free up a stuck ring, etc and stop the blowby. Don't think it will help the oil pressure, though.
 
Last edited:
BDF6 said:
If you're going to pull it & rebuild it maybe consider researching something like this:
https://www.cnc-motorsports.com/engine-parts/performance-rotating-assemblies/sb-chrysler-318-kits
A mild/moderate stroker is reliable & easy HP/TQ.
And quite fun I might add...
This company is just an example, I have no experience with them.
Click to expand...

I like this idea! If I'm going to rebuild the 318, why not? This is not a race car, so I would pick the cheaper kit. Car will always be a highway cruiser, but I would like more highway "get up and go".
 
A 318/390 is a great idea. Magnum or Engine Quest heads for a few extra HPs, headers and a modern cam will really wake it up too.
 
I had a worn out 318 in my 72 Charger when I got it. I had super low oil pressure and it started knocking soon after.
Since you have the 318 you could do a magnum swap? I swapped in a 360 Magnum and used parts from my 318 for the accessories. The one big expense was the carb intake.
good luck!
 
Great idea. Will the alternator and power steering pump fit on the front?
 
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