Help with 401 heads

I just completed a rebuild and paint of a 1973 401 engine and installed it in my Jeep CJ7.   After running the engine for a short time, I am noticing that there is a small amount of both oil and antifreeze weeping out of a factory accessory hole in the right front head. This hole is what I use for alternator mount!!!! It is not much - about a thimble amount of antifreeze/oil mix puddled on the timing chain housing.

I suspect that the head must be cracked on the inside causing both water from the water jacket and oil from the oil drain hole to sump.

While finding another 401 head may be impossible, can I consider using a head from an AMC 360 as a core for replacement? I have searched on this topic, but cannot find anything.

Any help would be appreciated. I spent a year (on and off) assembling and painting this engine to it looks show and now I may have to remove the darn head.

Note: I took an old 304 head and sliced about 1/2 of the edge off to see how deep the bolt hole goes as well as the surrounding oil gallery and water jacket. The blue dot is where the bolt hole is.



Edited by markbritt - Mar/20/2017 at 7:03pm

Heads off a 360 will work just fine.
If I remember correctly, the 360 and 401 engines used the exact same heads for a given year. Only the 304 had different heads with smaller valves.

Got a pic of it? That's an interesting place for a leak

Moffman wrote: Got a pic of it? That's an interesting place for a leak

I bet at one time either the hole was chased too far with a standard thread chase and cracked when bottomed, or undo pressure was exerted with a bolt still attached, possibly dropped or hit face down to the ground when pulled out of an engine bay. That area is thin and would not be the spot I would yank an engine with. Diagonal from front driver to rear passenger. Not diagonal front passenger to rear driver side, even though you can bolt up the heads to mount a chain with for pulling.

markbritt wrote: Picture - yes I have several and will post tonight. I have one of those diag cameras on the long want, so I was able to get right up to the hole. My main concern here is plugging the hole Yes, that will resolve the drips, but can this crack be large enough that anti will still flow into the oil behind the plug?

If you're lucky, you should be able to get away with plugging it with an insert and some sealer. To me the most concerning part is not only coolant but oil as well. How does your oil and coolant look, any cross contamination inside?