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Rear Main Seal


likeold
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You should get this repaired as soon as possible. Not only are you risking serious damage to your engine and clutch, you will soon have the entire underside of your car coated with oil.  You are also spreading oil on the road.  When it rains this becomes very slippery to drive on.  We don't need that.

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Basically, nothing should leak. All were designed to keep the oil inside. Leaks (especially significant ones), are a sign something is wrong.

The '38-40 series engine has no rear seal. Too much piston blow by can cause rear main leaks, so can loose main bearings.

Also check for plugged crankcase breathers.

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6 hours ago, likeold said:

When you say drain back tube, is the oil suppose to go back into the engine or on the floor? Can you see this tube on the outside of the engine?

 

You can't see it externally. I have a car with a similar setup, the oil that leaks from the rear main is supposed to go into a groove that drains through the tube back into the oil sump. All this is inside the pan. You aren't parking on a steep hill are you? There would be nothing to hold the oil back if so. If it leaks anyway something else is wrong. Check the stuff @DonMicheletti mentioned, starting with the breather(s) because that would be an inexpensive fix.

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On any breather system there has to be a "way in" and a "way out" for the crankcase ventilation air. The way out is a breather tube that is attached to the side of the engine. It points down. It creates a suction when the car is moving. I don't remember where the way in is on that car. Someone in this thread will probably know.

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There's a breather tube on the side of the engine.  There is also a set of small louvers on the end of the valve cover at the firewall.  The cap on the valve cover shown in your picture is correct; it's just an oil fill cap (not vented).

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There is a little breather filter on the drivers side of block near the rear, louvered vents at rear of valve cover. The breather tube is in your picture, look on the lifter cover, or straight below the spark plug cover bolt.

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I removed the breather does not appear to be super clogged but I assume you can't take this apart maybe just wash out in gasoline and blow it with air, sound right? The other picture I assume is the breather exit, if it is it appears to be sealed unless the hole is so tiny I can't see it, am I looking at the right thing? What to do next?

20211109_080830.jpg

20211109_080851.jpg

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22 minutes ago, EmTee said:

20211109_080851.jpg.c86f9806cbe1167095f8

 

That thing that looks like a bent tube is the valve handle for the engine block coolant drain petcock.

That makes more sense and it actually works!

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You may have to clean it good then see exactly where the oil is coming from. There is no rear journal seal but there are two side seals on the rear main cap. Duz the oil pan look to have been removed in the past? Bad/leaking oil pan gasket, maybe someone in the past might have tightened the pan bolts to stop a leak resulting in distorting the holes of the pan, and splitting the gasket, making leak worse.

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  • 2 weeks later...
2 hours ago, likeold said:

The more I drive it the less it leaks, now I like that fix!

 

Hopefully that's good news.  There's still oil in the crankcase, right...?  ^_^

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