Copyright by Goodheart-Willcox Co., Inc.
510 Auto Engine Repair
A B C
Seal
puller
Solid
shank
screwdriver
Drive out
old seal
Seal driver
New seal
Seal driver
Figure 23-24. A—Sometimes the front crankshaft seal can be replaced without removing the front cover. A special puller is used to remove the
seal. B—On most engines, the front cover must be removed for front crankshaft seal service. The oil seal is driven out from the back. Then,
a seal driver is used to install the new seal. C—Driving in a new front crankshaft seal with the front cover installed on the engine. (Toyota)
Place sealant by these areas before
installing the valve cover gasket
Camshaft seal driver
The seal housing surface
should be dry. Apply a light
coat of oil to the camshaft
and the inner lip of the seal.
Figure 23-25. With an OHC engine, a front seal may be
mounted in the cylinder head. A seal driver is the best way to
install the seal without damaging it. (Honda)
Engine Front Cover Service
The engine front cover, also called the timing cover,
holds the front oil seal and encloses the timing gears or chain.
It can be made of thin stamped, sheet metal or cast aluminum.
Scrape off all gasket material. Then, install the new oil
seal as described in the previous section. Make sure the cover
sealing surface is true. Lay it on a flat work surface and check
for gaps under the cover. Straighten the cover if needed.
Front Seal Service
The crankshaft front seal keeps engine oil from
leaking out from between the crankshaft snout and the
engine front cover. Replace the front seal whenever it is
leaking or the front cover is removed.
The front seal can be replaced in the vehicle with only
partial engine disassembly. Typically, you must remove
the radiator and other accessory units on the front of the
engine. Use a puller to remove the vibration damper.
Sometimes, the front crankshaft seal can be replaced
without front cover removal. Shown in Figure 23-24A, a
special seal puller may be used to remove the old seal.
Some crankshaft front seals are pressed-in from the rear of
the timing cover. In these cases, timing cover removal is
needed for seal replacement. After the cover is removed,
drive the old seal out, as shown in Figure 23-24B.
Always compare the old seal with the new one. The
outside and inside diameters of the two seals must be
the same. You may also be able to match part numbers
stamped on the metal flange of the seals.
Before installing a front seal, coat the outside dia meter
of the seal with nonhardening sealer. This will prevent oil
seepage between the seal body and the front cover. Coat
the rubber sealing lip with engine oil. This will lubricate
the seal during initial engine startup. Then, use a seal driver
to squarely seat the new seal into its bore, Figures 23-24B
and 23-24C. If the front cover has been removed, install it
as described in the next section.
When available, a seal driver should be used to install
the front seal. However, if you do not have one, a block
of wood can be used. Drive the seal in squarely without
damaging the metal housing of the seal.
Some camshafts also have a front seal. It seals the front
camshaft bearing of an OHC engine. Figure 23-25 shows a
technician installing a camshaft front seal in a cylinder head.
The outside diameter of this type of seal should be coated
with nonhardening sealer. The seal housing surface should
be dry. Place engine oil or grease on the inside diameter of
the seal and on the camshaft. Then, drive the seal in.
Sealing the Front Cover
A front-end gasket set often includes the gaskets, oil
seals, sealer, and other parts needed to replace a timing
cover with the oil pan on the engine. Either a conventional
gasket or chemical sealant can be used during front cover
installation. Usually, both a gasket and sealer are used.
Make sure you use a bead of sealer where two gaskets or
parts come together. This is a common leakage point. Also,