If you have ever experienced the joy of doing a plumbing project you learn very quickly about how the proper
amount of heat in the right place will literally leach the solder into
the joint to seal the copper pipe properly – or not. It becomes obvious where you
failed to do so once you open the main water valve and you suddenly
realize you have a leak.

That is exactly what can happen with the 3.0L DOHC Duratec Ford
engines. In particular, those engines manufactured for the 1999 model
year vehicle applications may have a greater tendency to leak.

It seems that engines built prior to 6/15/1999 used one head gasket and
cylinder head/block combination and after that date used another. All
of the casting numbers and details will be coming in an article later
this year but for right now we are going to give you the basic
information and images to keep you from having a leaker.

There are three different areas which clearly identify which head
gasket is which and a small change was made to the coolant port area
between cylinders No. 2 and No. 4 on the right bank.

If the wrong style head gasket is used you will have a coolant leak to
the exterior of the engine, which on initial start up changes your
shoulder posture from bold and robust to hunched over and distraught,
usually with a small moan connected to it. So before that happens let
me give you that "one thing" you need to know: if you have an F5 or F7
block use the early gasket; if it is an XW block use the later gasket.

If you look at the pictures you can see why. First
compare the head gaskets early and late (Figure 1), noticing the three
different color boxes on both gaskets, and corresponding expanded views
with the same color borders (Figures 2, 3 and 4). All the pictures show
the early view on the top and late view on the bottom. Then look at the
expanded view of the cylinder head (Figure 5) and you can see the minor
difference in the castings.

Put the wrong gasket on the wrong head and you’ll have your leaker.