The '66 is leak free. I just looked down through the empty engine compartment at the nice clean and dry garage floor to double check .
But seriously. Certain things like the front seal on the A/C compressor need a bit of run in time. Items like the PS ram require just asuper slight filmof fluid on the rod to keep the seal from rubbing and prematurely wearing. Other seals are designed to goon dry, and if lubricated upon assembly will leak no matter what.
From my experience, the common issues causing leakage after a fresh rebuildhave to do with either lack of attention to detail on inspection and assembly, lack of following instructions for the specific part, or improper bedding in of components. Yeah, every now and then a faulty part will come out of the box, but most of those should be caught during inspection for reassembly.

 

Does anyone know how many areas on a Mustang are potental leak sources? A dozen, two dozen...

 

Oh, if someone does know-could you list them in order of common leak occurances? Very curious.

 

I can't really say I am 100% leak free, but nothing drips on the garage floor. About once a year I detail the engine because it has some oil seepage around the gaskets and dirt collects there. Nothing that most cars don't have though.

 

My new engine rebuild has a seaping leak at the front of the oil pan flange, mainly due to the fact I reused my somewhat beat up old oil pan and the flange wasn't totally straight, I got it as best I could but it seaps a bit at the bottom of the timing cover. Using the Fel Pro 1 piece rubber/steel gasket, actually works really well, goes on totally dry, but you need to have a near perfect mating surface on both sides, and I don't. It gives me an excuse to eventually get a good baffled pan anyway

There also is a rather large fuel leak coming from my lead foot, but I'm not sure if that's classified as a leak per se.

And like Soaring said, pretty much every car has a leak somewhere, when 2 surfaces come together there's never a truely perfect seal, unless you weld parts together.

 

hmmmm, maybe i should weld my oil pan, water pump, heads, and anything else i can think of to the block

problem solved

 

That's about it. Unless it's welded there's a joint, and joints always run the risk of leaking. Most oil pans do seep over time though, oil just has a way of getting into those really hard to reach places...mainly since that's what it's formulated to do