340 oil leak

Hi all, I own a 1969 Dodge Dart with a 340 in it and the motor has a fresh rebuild on it. Probably only have 500 miles on it. I have a fairly big leak coming from the lowest point in the oil filter base plate. I've tried changing gaskets, silicones, tried putting the 90 degree adapter back on and I still have the same problem. It's about a dime size drip every 3 seconds at idle. I'm completely lost and the machinist has no idea what is wrong with it too. It's my first car and first restoration and I'd really like to have it all fix up again for the summer. Thanks in advance.

Since you said you swapped the base plate out for the 90 degree adapter I will assume the base isn't the problem.

1. It is common for the gasket to get stuck in the block around the filter adapter. A small chunk can go unnoticed. Remove the baseplate/adapter and be very very careful about making sure it's clean enough.

2. Check for oil trickling down the block from the end of the manifold/distributor/valve cover. Very common too.

3. Make sure you use new gaskets. Kits are available from the dealer for the 90 degree adapter. Don't expect silicone alone to take that kind of pressure without a good fiber gasket to grip to.

4. If you go back to the base plate use a 340/360/5.9 plate which has 6 to 8 holes or redrill the 4 hole 318 plate to have 8 holes.

5. Make sure there is a little space between the center of the plate and the block when no gaskets are installed. It provides crush on the gasket. If none exists a hammer can persuade it to have some.

No gasket under the center of the plate. Only around the edge.

Hope it helps

Thank you I'll try that out. I do have a little bit of a leak out of the oil fill cap when it's driven for a extended period of time. And I have gotten the base plate to seal before. First time it was silicone and a gasket and that lasted about 300 miles second time it was just a gasket lasted about 100 miles and all the other times it's about 15 minutes tops....

If you buy a new plate from the dealer it might be a bit thinner than an original 60's/ 70's one. I measured them and the old one was .010 or so thicker.

Wonder if the plate is warped?

I've checked the plate and its flat, not bent or warped from what I can see, and I can't see any imperfections in the block either.... I'll try a new plate though.... But the dealership says they cant get them anymore?

Felpro sells the large circular gasket seperately & it's a bit thicker than the one in the 3 piece MP gasket kit. As said clean the circular block recess squeaky clean & glue the gasket up there with permatex 99MA "high tack" the red gasket cement/glue. As you lift the 90 deg adapter up in place have it clocked correctly so you dont rotate it & ahead of time mockup & see what exact position you need for filter clearance. If using the flat plate confirm it is flat & as said doubling the holes is good (deburr em) since it is already out/in hand. #1 clean gasket recess (2) flat plate (3) oil the circular/flat/thin built in gasket on the filter. EDIT I would get anouther used flat plate to be proactive/be done with it. MORE EDIT Felpro 70078 (iirc)

Oil leaks are a common Mopar problem to have - take the detailed advise and keep listening to what your guts been saying - maybe you'll find an nos part in time - create a wanted ad here for good used or yes try local j-yards, great looking ride, thanks for posting, good luck.

My thinking is it has to be the plate. I pretty sure I have a NOS one if you can`t find one locally.

http://www.summitracing.com/parts/ctr-22-575/overview/make/dodge

ends your oil leaks forever...

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I've checked the plate and its flat, not bent or warped from what I can see, and I can't see any imperfections in the block either.... I'll try a new plate though.... But the dealership says they cant get them anymore?

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Flat isn't helpful unfortunately.
It has to have crush. If the inside edge contacts the block before the outside edge crushes the gasket, it will leak. Without a gasket there should be about 1/16" gap between the center of the plate and the block.

The dealer should be able to get a new one. It is the same plate on the 5.9 Magnums made through 2003. If they can't then that one from summit is a sexy piece. but a little pricey.

53021053 PLATE. Oil Filter Adapter. . PLATE, Oil Filter Adapter. 1991-93.
PLATE. Oil Filter Adapter. . ST. Required: 001 $4.86 53021053

53020461AB GASKET. Oil Filter Adapter. . GASKET, Oil Filter Adapter Plate.
GASKET. Oil Filter Adapter. . ST. Required: 001 $3.38 53020461AB