351C Oiling question.

Danr55 · #1 (**permalink**) 12-01-2007, 05:45 PM

I just finished changing head gaskets in my 351C motor. I noticed that the middle oil return passage in the gasket as just a small hole (Maybe .093 diameter). Now after I run for a while, the oil pressure drops and the oil seems to be blowing out the breather cap. Its appears as though I'm filling the valve covers with oil. I checked on the old head gasket and the hole was about the same diameter.

Would I be way off base to take a drill and open up that return hole in each side?

767Jockey · #2 (**permalink**) 12-01-2007, 05:52 PM

It doesn't sound like the hole you describe is the problem since the hole in the old gasket is the same size. 351C head gaskets are very easy to install backward - you sure you have them in the right way? They should be labeled "TOP" clearly on one side, make sure that faces up when you install them.

I sure wouldn't drill that hole out with the engine is assembled, if that's what you mean (which I doubt). Little bits of gasket debris can wreak havoc inside the engine. If you're going to take it apart again anyway, triple check that you have the gaskets in correctly, it's REALLY easy to make a mistake.

Woodz428 · #3 (**permalink**) 12-01-2007, 08:47 PM

The oil drain back holes are on either end toward the top of the head and drain into the valley area. That is about the only way that you would be filling the heads, these holes being plugged. You can examine them with the valve covers off and see if they are restricted. You should also have oil leaking at the valve cover gasket from the heads not draining.

Jac Mac · #4 (**permalink**) 12-02-2007, 12:43 AM

There is no center/middle oil drain on a 351c head gasket, there is also no 'Top' mark on the gasket, only a 'Front'- easy check- most Ford SB head gaskets[incl 351c] have a 'square' corner at lower front on both sides- for most production gaskets. This also means one gasket will appear to be upside down when fitted.With reference to the 351c, provision is made for in/ex notches to allow fitting to both sides. Aftermarket & SVO gaskets can be left/right handed for the ex/in notches in some applications and are marked as such.

With ref to your problem, someone hasnt left a bit of rag or paper towel etc in the drain back holes at each end of the head while fitting valve springs etc have they, I did a 200mile round trip to find that one night after a 'clever gent' didnt remove them after changing springs and ended up with the same problem your dealing with - I was not a happy camper

by the time I got home!!

Jac Mac

Danr55 · #5 (**permalink**) 12-02-2007, 07:46 AM

Well guys.. I'm using Cometics gaskets and they are clearly marked for front. I checked and double checked the orientation before I cinched down the head. The gaskets are installed correctly. There is nothing in the drainback holes in the corners of the heads. These are all things I've thought of and checked already. That's one of the reasons I'm so puzzled..