Strange source of an oil leak????

[10drum]

Greeting,

I have a 69 C-10 with a 307, just under 50K, yes it's actual milage. I've been trying to run down an oil leak. It was coming from the back of the driver side head. I had changed the valve cover gasket, that wasn't is it. I changed the intake manifold gasket and was able to get back there and clean everything real good, and the leak seems to be coming from the head gasket???, so I pulled the head and found this plug, See Photo. It's tucked up under the head. It looks like it is a port to the oil psi take off. I'm not sure but I think that may be the source. I'm not having any luck getting it out, it's a 1/4" drive but I need a good hard drive because I've already broke my 1/4" break over and a 3/8 to 1/4 reducer. I'm letting it soak tonight and will try heat tomorrow. Any suggestions? Thanks for all replies. Phil

[10drum]

I hope this gets the photo loaded.

[Grumpy old man]

Hi , Clean it spotless then use old school Permatex gasket sealer ,Also anytime your searching for a hidden oil leak ...

clean the area,and blow it dry with high pressure air , then dust the area with talcum powder ,check your oil level and run it again , the powder will lead you directly to the leak and save you from pulling heads when it just may be the sending unit or the intake gasket that's famous for leaking ?

[hamjet]

You can't tell if thats leaking for sure, but you went that far. take a punch , stick it in the square hole, crack it a few times to break any sealer, rust. then run the torch around the perimeter of the plug getting the block hot but not the plug, try to loosen it then. It you get it, clean the plug on a wire wheel, clean the hole, use something like Indian Head shellac to seal. Hopfully with the new head gasket, and intake gasket, what ever the problem was should solve the leak...

[chopnchaneled]

Had a leak like you and it turned out to be the gasket under the distributer.
Just a thought

[10drum]

Thanks for all the replies. I'm retired from a major pipeline and was responsible for the maintenance of 100s of hydraulically operated valves, so I'm a leak fighter from way back. It is not coming from the distributor (it would down the passenger side). The oil psi sending line is not leaking either. I replaced the intake gasket and cleaned the back of the engine and it does appear to seeping from between the head gasket and the block which doesn't make sense unless the top ridge of the head gasket didn't seal correctly. The plug is under pressure and the intake is not, That's why I think it may be the plug. Thanks for the replies.

[GRX]

Fairly unusual for that plug to leak but it does happen. It is there to block the end of the factory drill which completes the connection from oil filter to the central lateral galley. I like to remove that plug on all my rebuilds to be sure the whole oiling system was cleaned. A torch is mandatory so remove in the manner hamjet laid out.

[10drum]

I examined the intake gasket, the plug, and the head gasket and i'm pretty sure it was leaking around the top corner of the head gasket. i think it was a bad gasket to begin with the front top corner has a groove pressed in it and back top corner looks like the groove did not get pressed in right. I attached some photos, The first one is the rear and the second one is the front. Thanks for all the help. I hope the photos uploaded. Phil

[Fitz]

Originally Posted by 10drum

I examined the intake gasket, the plug, and the head gasket and i'm pretty sure it was leaking around the top corner of the head gasket. i think it was a bad gasket to begin with the front top corner has a groove pressed in it and back top corner looks like the groove did not get pressed in right. I attached some photos, The first one is the rear and the second one is the front. Thanks for all the help. I hope the photos uploaded. Phil

Looks like someone dropped the head down just slightly cocked on that side which crushed that portion of the gasket.

Install a new gasket and be sure to lower the head in place flat and square to the deck without letting it drop.

[MikeB]

If it was just a bare block that you could clean out, you could drill a hole in it and remove it with a screw extractor like this:


But if you can't get it out after soaking with penetrating lube or with heat, clean the plug and surrounding area really well, and then put some hi-temp, oil-resistant RTV on it.

As I recall, the head gasket does not seal the entire plug, does it?

I just found this on another website:

Keith’s shop removes the oil galley plug at the back of the block near the oil pressure galley with wax and a torch. These plugs must be heated up for removal because they are installed at the foundry when the block is still hot. As the block cools down, it secures the plug into the block. The only safe way to remove the plug is with a torch.

[rcazwillis]

You have to heat the plug, not the block. Notice in the pic, the torch is on the plug. I have used this on oil galley plugs that were frozen. Heat the plug, while it is still red unscrew it. It has always worked for me.

Originally Posted by MikeB

If it was just a bare block that you could clean out, you could drill a hole in it and remove it with a screw extractor like this:


But if you can't get it out after soaking with penetrating lube or with heat, clean the plug and surrounding area really well, and then put some hi-temp, oil-resistant RTV on it.

As I recall, the head gasket does not seal the entire plug, does it?

I just found this on another website:

Keith’s shop removes the oil galley plug at the back of the block near the oil pressure galley with wax and a torch. These plugs must be heated up for removal because they are installed at the foundry when the block is still hot. As the block cools down, it secures the plug into the block. The only safe way to remove the plug is with a torch.