1991 1999 ford explorer chilton User Manual

							Remove the valve seal from the valve stem-O-ring type seal shown
Removing an umbrella/positive type seal
If equipped, remove the valve seal. If the seal is difficult to remove with the valve in place, try
removing the valve first, then the seal. Follow the steps below for valve removal.
6.  HOW TO USE THIS BOOK
DISASSEMBLY 455 
						

							Invert the cylinder head and withdraw the valve from the valve guide bore
Position the head to allow access for withdrawing the valve.
7. 
Cylinder heads that have seen a lot of miles and/or abuse may have mushroomed the valve lock grove
and/or tip, causing difficulty in removal of the valve. If this has happened, use a metal file to carefully
remove the high spots around the lock grooves and/or tip. Only file it enough to allow removal.
Remove the valve from the cylinder head.
8. 
If equipped, remove the valve spring shim. A small magnetic tool or screwdriver will aid in removal.
9. 
Repeat Steps 3 though 9 until all of the valves have been removed.
10. 
2.3L, 2.5L and 4.0L SOHC (VIN E) Engines
Whether it is a single or dual overhead camshaft cylinder head, the disassembly procedure is relatively
unchanged. One aspect to pay attention to is careful labeling of the parts on the dual camshaft cylinder head.
There will be an intake camshaft and followers as well as an exhaust camshaft and followers and they must be
labeled as such. In some cases, the components are identical and could easily be installed incorrectly. DO
NOT MIX THEM UP! Determining which is which is very simple; the intake camshaft and components are
on the same side of the head as was the intake manifold. Conversely, the exhaust camshaft and components
are on the same side of the head as was the exhaust manifold. HOW TO USE THIS BOOK
456 DISASSEMBLY 
						

							Exploded view of a valve, seal, spring, retainer and locks from an OHC cylinder head HOW TO USE THIS BOOK
DISASSEMBLY 457 
						

							Example of a multi-valve cylinder head. Note how it has 2 intake and 2 exhaust valve ports
C-clamp type spring compressor and an OHC spring removal tool (center) for cup type followers
HOW TO USE THIS BOOK
458 DISASSEMBLY 
						

							The 4.0L SOHC engine cylinder heads retain the camshaft using bolt-on bearing caps
Most cylinder heads with rocker arm-type camshaft followers are easily disassembled using a standard valve
spring compressor. However, certain models may not have enough open space around the spring for the
standard tool and may require you to use a C-clamp style compressor tool instead.
Example of the shaft mounted rocker arms on some OHC headsHOW TO USE THIS BOOK
DISASSEMBLY 459 
						

							Another example of the rocker arm type OHC head. This model uses a follower under the
camshaft
If not already removed, remove the rocker arms and/or shafts and the camshaft. If applicable, also
remove the hydraulic lash adjusters. Mark their positions for assembly.
1. 
Before the camshaft can be removed, all of the followers must first be removed ... HOW TO USE THIS BOOK
460 DISASSEMBLY 
						

							... then the camshaft can be removed by sliding it out (shown), or unbolting a bearing cap (not
shown)
Position the cylinder head to allow access to the valve spring.
2. 
Use a valve spring compressor tool to relieve the spring tension from the retainer.
3. 
Compress the valve spring ...
Due to engine varnish, the retainer may stick to the valve locks. A gentle tap with a hammer may help
to break it loose. HOW TO USE THIS BOOK
DISASSEMBLY 461 
						

							... then remove the valve locks from the valve stem and spring retainer
Remove the valve locks from the valve tip and/or retainer. A small magnet may help in removing the
small locks.
4. 
Lift the valve spring, tool and all, off of the valve stem.
5. 
Remove the valve spring and retainer from the cylinder head
If equipped, remove the valve seal. If the seal is difficult to remove with the valve in place, try
removing the valve first, then the seal. Follow the steps below for valve removal.
6.  HOW TO USE THIS BOOK
462 DISASSEMBLY 
						

							Remove the valve seal from the guide. Some gentle prying or pliers may help to remove
stubborn ones
Position the head to allow access for withdrawing the valve.
7. 
Cylinder heads that have seen a lot of miles and/or abuse may have mushroomed the valve lock grove
and/or tip, causing difficulty in removal of the valve. If this has happened, use a metal file to carefully
remove the high spots around the lock grooves and/or tip. Only file it enough to allow removal.
Remove the valve from the cylinder head.
8. 
All aluminum and some cast iron heads will have these valve spring shims. Remove all of them as well
If equipped, remove the valve spring shim. A small magnetic tool or screwdriver will aid in removal.
9. 
Repeat Steps 3 though 9 until all of the valves have been removed.
10.  HOW TO USE THIS BOOK
DISASSEMBLY 463 
						

							
INSPECTION
Now that all of the cylinder head components are clean, its time to inspect them for wear and/or damage. To
accurately inspect them, you will need some specialized tools:
A 0-1 in. micrometer for the valves
· 
A dial indicator or inside diameter gauge for the valve guides
· 
A spring pressure test gauge
· 
If you do not have access to the proper tools, you may want to bring the components to a shop that does.
Valves
The first thing to inspect are the valve heads. Look closely at the head, margin and face for any cracks,
excessive wear or burning. The margin is the best place to look for burning. It should have a squared edge
with an even width all around the diameter. When a valve burns, the margin will look melted and the edges
rounded. Also inspect the valve head for any signs of tulipping. This will show as a lifting of the edges or
dishing in the center of the head and will usually not occur to all of the valves. All of the heads should look
the same, any that seem dished more than others are probably bad. Next, inspect the valve lock grooves and
valve tips. Check for any burrs around the lock grooves, especially if you had to file them to remove the
valve. Valve tips should appear flat, although slight rounding with high mileage engines is normal. Slightly
worn valve tips will need to be machined flat. Last, measure the valve stem diameter with the micrometer.
Measure the area that rides within the guide, especially towards the tip where most of the wear occurs. Take
several measurements along its length and compare them to each other. Wear should be even along the length
with little to no taper. If no minimum diameter is given in the specifications, then the stem should not read
more than 0.001 in. (0.025mm) below the unworn portion of the stem. Any valves that fail these inspections
should be replaced.
Valve stems may be rolled on a flat surface to check for bendsHOW TO USE THIS BOOK
464 INSPECTION