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Hello fellow club members.

My 1972 Custom 454 Big Block leaks oil. A lot...

The rear main seal has been replaced. The seal for the harmonic balancer was replaced. New gasket for the oil pan and valve covers. New seal and fuel pump replaced. Having to add about a quart or more after sitting for a week. I have been using NAPA High Mileage SAE 20W-50 non synthetic oil since it is the original motor.  The oil leaks seem to be mainly dripping from the front but I am assuming oil is shooting all over as I am driving because of all the various areas. The passenger side seems to be the main area. Also see oil running down the lower radiator hose as well. Have added die to the oil and shows a "slight" stain of green from the timing chain area. But again, no real noticeable area that gives off this much oil. Aside from getting a new motor I am at a loss to what to do next. The mileage shows 37,000 which I am assuming is 137,000. Any suggestions or anyone that had this issue before would be greatly appreciated!!

Thanks!! 

oil.jpeg

engine.jpeg

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Alright. Silly question, is the plug, under the fuel pump, on the block there or loose? Also, check the 2 bolt holes on the front of the block by the fuel pump and timing chain cover. The upper hole may be open. 

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That looks like several leaks. I had a bad oil leak from my intake manifold once when the gasket didn’t sit properly. New valve cover gaskets can leak when they shrink. Are the valve cover bolts loose? Maybe the edge of the valve covers aren’t flat and therefore not sealing properly all the way around.

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Thank you for your suggestions. The plug near the fuel pump is intake. I will double check the two bolts you are referring to. I will also double check the value cover bolts but no evidence of leaking seems to be coming from them or upper side. Seems to be focused on the bottom passenger side and the multiple puddles also seem appears after I drive which I believe the air is shooting oil all over. Again, no one place that seems to be the place of origin. Very frustrating!!

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I had multiple leaks on mine. Valve cover gaskets, intake gasket and my power steering pressure line was leaking that I thought was coming from the engine.

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I did replace the original oil pan with an aftermarket. Since then the gasket has been changed twice thinking that maybe the cause. Did not help. Cleaning up the original pan and going to put it back on to see if that helps.

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4 hours ago, Jsd454 said:

I did replace the original oil pan with an aftermarket. Since then the gasket has been changed twice thinking that maybe the cause. Did not help. Cleaning up the original pan and going to put it back on to see if that helps.

Unless the original has been the recipient of some egregious contact with a fixed object (i.e. ramping it on a parking pillar, God forbid!) that can’t be massaged out, OE is the way to go. My first car in high school was a hand me down 67 Camaro that I just HAD to put chrome valve covers on. They leaked each time, every time after four gasket changes. Bone dry with the original stock Chevrolets, but I was too cool for Chevy orange, lol. I’ll bet that particular leak clears up upon putting the original pan back on. Keep us posted. 

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  • 2 months later...

Your timing chain may have been replaced at one time. A trick on reinstalling the cover without dropping the oil pan was to snip off a little piece of the metal at each side where it meets the block And oil pan.

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Can you see oil running down the side of motor from the top of motor? If not that should tell you its a lower end of the motor leak. Looks like oil pan to me since there is a leak on both sides of motor. Shouldn't be that hard to find being the size of the leak.

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Make sure the rear of the intake was sealed. I had to replace mine twice. when I set the manifold I screwed up the rear seal and it was leaking. Run a rag along the back of the manifold and check for oil.

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With higher miles,  possibly a groove in the harmonic balancer from the seal riding on it?   Even with a new seal the balancer may be throwing oil around.     I had to put a repair sleeve on my 402’s balancer.  

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