[pjarrett]

Hey everyone. I have an oil leak in my 327. Using the dye and the UV light I have been able to eliminate where the problem is NOT originating from. I need some ideas as to where it is comming from.

The light indicates there it is originating just below the number seven cylinder. There is a place on the bell housing where there is a small puddle, and it drips from there. It's definately not comming from the head either.

It's NOT the valve cover gaskets, intake manifold gasket, oil sending unit, distributor, or road draft tube fitting. There is NO burning oil, so I am assuming it's NOT comming from bad rings through a head gasket. No leak from the header gasket either. UV light does NOT show any leakage from the oil filter adaptor, or anywhere inside the bellhousing. I'm speculating there is some bolt or fitting that goes into the block above the bellhousing that might be leaking.

It takes 7 to 10 minutes for the leak to start. It's not dependent on the car moving. Any thoughts?

[pjarrett]

I can see why nobody replied. My car is jinxed

[T-bucket23]

Clean it and watch it while it is running. My GUESS is the back of the intake or the oil sender. If it is puddling on top of the tranny these are about the most likely causes. You said you put die in it to use with a blck light I assume. Some of those dyes also require special glasses to see them well.
If you clean it and get a mirror behind that side of the engine it should be obvious. It is real important to clean it first so a fresh leak will be easy to spot.
There may also be a plug in the block or the head that is leaking.

[Mr. Wormy]

rear main seal???

[pjarrett]

Thanks for responding. It might be a plug in the back of the block. There are NO plugs in the head.

Definatley not the rear main

[docvette]

Doc here,

It could be the plastic in the sender, heating up and dripping oil through a small crack and allowing time enough for it to settle to the bottom of the block..

When relatively cool, small cracks won't leak or so small as not to see them..

Doc

[pjarrett]

Not a bad place to check. However, If the leak was on the sending unit somewhere I would have seen the leak with the UV light. With the additive I put in the oil, and the UV light it's very clear that the leak is NOT comming from the sending unit or the feed going through to the dash board.

Thanks for the input

[cucumber1949]

I am attempting to deal with the same problem on my 350, except I know it is weeping small amounts of oil from the oil sending unit hole in the rear of the block. This puddles in the exact location you are seeing and eventually drips down the left side of the bell housing, and finally drips a few drops off the rear left side of the bell housing. The sender is not leaking, but the short threaded tube (1/8" pipe thread in this case) that screws into the hole in the block - that is the joint that weeps oil. I've tried several times to fix it - used steel and brass tubes, thread sealants, yellow pipe thread tape, never gets better, never gets worse. No cracks. Maybe I'm just afraid to tighten it too much, but when I tighten it now it feels like I'm tightening that small piece of pipe a LOT! I'm thinking my next move will be to plug that location and install the sender in one of the other two locations that are common on these blocks.

If I'm just lightly cruising, it won't leak very much at all if any, but if I've wound it up there will be small puddle in that location, no more than 3 or 4 drops after a while. Obviously leaking more when oil pressure is higher. I've just gotten used to wiping that location with a rag, paper towel, napkin, whatever is handy as the location is readily accessible.

Just my $.02.

[pjarrett]

That symptom sounds very similar to mine. After 10 minutes it starts to leak. However, it's not just a trickle, it's quite a bit. I could plug the sending unit just to try it out.

I need to find out if there are ANY plugs above the bell housing, and below the head. I can't imagine a crack anywhere in the block back there, but thats the ONLY thing I can deductively come to reason with. I am certainly positive there is no leak coming above from any gaskets, seals, or sending unit. I would see the drips coming from the UV light.

It's a 1967 327 block and I need to find investigate the possibility of a plug going to an oil gallery back there.

Thanks for your .02 cents

[SAATR]

The only oil gallery plugs on the back of the block are going to be under the bellhousing, so if the leak is not originating there and dripping through the inspection cover or in the bellhousing then that is not going to be your leak. About all that leaves on the back of the block are the valve covers, rear intake seal, and the oil sending unit and its related adapter. I would get some degreaser and clean the bellhousing and back of the block thoroughly before looking for a leak. Usually the best way to track leaks is to start at the highest and most forward location where the leak may be originating and work your way down and back. Be sure to use the special glasses with the light and dye kit as it is very difficult to see the dye without them, and don't be shy about using the stuff; if you don't put enough in, it will hardly show up at all, even with the glasses. Another thing: try not to drive the car while looking for the leak, as the airflow has a tendency to blow oil all over the place, making pinpointing the leak all the more difficult. If all else fails you could always try the shotgun approach: replace the intake gaskets, V/C gaskets and pressure sending unit, and put a little thread sealant on the adapter fitting; but only as a last resort. Hope you get it fixed!

[LanceM]

This worked for me once on a hard to find leak. Clean everything really well, let dry. Get a couple of cans of spray foot powder and spray down everything/everywhere on the block where you think the leak is happening. Run the engine, the oil is easy to see seeping through the white powder. A quick power wash will take off the powder.

Lance

[pjarrett]

I think I found the leak comming from the head gasket