Replacing The Front Crankshaft Seal

Oil underneath the oil pan and front cross member of my 1978 Jaguar XJ-S was the first clue that something was amiss. Locating a leaking crankshaft seal is not for the faint hearted. Crawling under the V-12 at four thousand RPM will make grown men weep. The trail of oil from underneath the crankshaft damper was unmistakable. The seal would have to be replaced.

I recommend removing the radiator support, fans and fan shroud. It's critical that you have fairly good access to the front crankshaft area.

Remove all belts from the engine.

In order to remove the crankshaft bolt, the engine must be prevented from turning. There are a number of ways to accomplish this. Don't use a screwdriver to jam the ring gear teeth, you might damage them. My recommendation is to remove the torque converter inspection plate and use a vice-grip to clamp down on the flywheel ring gear. Turning the engine will cause exhaust pipe to stop the rotation of the vise grip. (red arrow)

Remove crankshaft pulley. The pulley has a hex nut that bolts to the damper. (See blue arrow 2nd photograph). The hex nut installs with two bolts with spacers (red arrow, 2nd photograph). This hex nut assembly must be removed to gain access to the crankshaft bolt.

The crankshaft bolt requires a 34mm socket. I was unable to find this socket in a 3/4" drive. I used a 1 5/16 inch six point 3/4" drive socket instead.

Even with a breaker bar attached, I had to augment leverage with an extension to get the crankshaft bolt loose.

Use the appropriate puller to withdraw the crankshaft damper.

The special damper "cone" is now visible on the front of the crankshaft. Remove the crankshaft cone by pulling straight out.(blue arrow)

The damper assembly uses two identical keys. One locates the damper to the cone. The other (red arrow below) locates the cone to the crankshaft. Remove the crankshaft cone key. Note the keys are identical and are positioned on opposite sides on the crank / cone assembly. Save these keys. Tap out gently with a small screwdriver if necessary.

At this point I found it easier to work from underneath the car. Use jack stands or ramps. You will be under there for a while. I also removed the oil cooler return hose for better accessibility.

Remove "distance spacer" (red arrow). This sleeve locates the crankshaft cone and provides a replaceable sealing surface for the crankshaft seal.

The Jaguar V-12 crankshaft damper assembly is either an engineering masterpiece or another example of Jaguar overcomplicating an existing proven design. I suspect there is a bit of truth in both statements. The assembly works by having the crankshaft bolt force the damper against a collapsible cone that transfers the holding friction to the crankshaft nose. (Proper reassembly is critical). In addition the design uses a "distance spacer" to position the cone and provide a replaceable sealing surface for the crankshaft seal.

I butchered up an existing screwdriver to use in removing the old oil seal.

There are two indentations at either side of the cover that facilitates removal of the seal. The easiest method for removal is to simply punch a slot in the seal at the indentation and pry out the seal (red arrow).

Note: Carefully clean the seal mounting area. Any nicks incurred during the removal process must be addressed now.

All crank seals for the V-12 are identical. Jaguar initially listed a part number for the seal only for the early cars. That listing has been discontinued, and the only seal currently available from Jaguar includes a new "distance spacer". It is also not cheap. Even from a third party supplier expect to pay approx. $70.00 US for seal and spacer. (Jaguar part number JLM 10613).

For those who hate to spend money, NAPA (auto parts chain in the US) sells just the seal for approx $10.00 US (part number 21098)

Pictured below is the old seal (green arrow), old distance spacer (blue arrow) along with the Jaguar seal and distance spacer (red arrow) The Jaguar seal has a rubber coating impregnating the outer band. This affords a better seal between the outer seal and the crankshaft cover. Interesting, it does not have the compression spring, which the original seal had and has become the norm for this type of seal.

Note the orientation of the old seal, (green arrow) it was installed with the lip out. This is the way it was removed, and based on everything I know, was installed backwards at the factory.

There are two ways to install this seal. Hammer in, or press it in. You can hammer it in, however close quarters and the possibility of damaging the seal precludes that idea. My recommendation is to press the seal in. I fabricated a press that uses the crankshaft bolt as leverage. I purchased a 2 to 1 1/2 inch galvanized pipe reducer from Home Depot. Any plumbing store will have this. The 2-inch side is exactly what I need to address the seal. The 2" side will be used to press the seal in. The height of the reducer is critical. Measure 1 7/8 inch from the 2" side and cut the pipe at exactly 1 7/8 inches. (Measure from the 2-inch side. Cut from the 1 1/4 inch side.)

I used a flat file to get the 2-inch surface perfectly flat. This is not absolutely necessary, however you might as well make this the right way.

As seen in the photograph below the 2" side of the pipe (red arrow) union mates exactly with the NAPA oil seal (blue arrow) The yellow arrow identifies the Jaguar seal.

The crankshaft bolt (blue arrow) will be used to force the modified pipe union (green arrow) against the new seal (red arrow) thus pressing it into the crankshaft cover.

Photographed below are the following:

Cone (pink arrow)

Old seal (yellow arrow)

New NAPA seal (blue arrow)

New Jaguar seal (red arrow)

New and old distance spacers (green arrow)

Inspect the crankshaft and collapsible cone keys. If there are any nicks incurred during removal of the keys, dress the keys up on a flat file.

In addition, make sure the keys fit the appropriate groves in the cone and damper.

Prior to installation, Oil the sealing surface of the crankshaft seal.

The NAPA seal has a standard uncoated metal outer ring with the usual compression spring around the sealing lip. If you are using the NAPA seal I recommend a thin coating of non-hardening Permetex around the outer perimeter on the seal (green arrow). This will mask any slight imperfections that might occur as the seal is pressed in. If you are installing the Jaguar seal this step is not necessary due to the existing rubber coating on the seal ring.

Position the seal (blue arrow) to the crankshaft cover. The seal in unidirectional, it must be installed with the lip towards the engine.

Make sure the seal is centered and slightly inside the mounting flange.

Position the "Press" over the outer ring of the seal (red arrow) and hand tighten the crankshaft bolt snug to the press.

Tighten slowly with a socket until the seal is flush against the crankshaft cover.

Make sure the new spacer is coated liberally with engine oil before installing. If installing the NAPA seal only, clean the distance spacer, oil, reverse and install. By reversing the spacer the oil seal lip is afforded a new surface to seal against.

The tolerance of the new spacer to the crank is miniscule. If it is not offered to the crank nose exactly square it will not go on. Do not force it. If necessary use the crankshaft bolt to move the spacer along the crankshaft. When seated, the spacer (blue arrow) should protrude slightly in relationship to the crank seal (red arrow).

Clean the crankshaft damper, cone and crank. All surfaces that the collapsible cone will come in contact with must be clean and oil free. Install crankshaft key. Offer cone to crankshaft making sure the crankshaft key lines up with the key slot in the cone (red arrows).

Cone should bottom out against distance spacer.

Install cone key. Offer damper to cone and install crankshaft nut.

Get the big socket and breaker bar out. Recommended torque is 150 lbs. I used a 3/4-inch breaker bar, with an extension and tightened two grunts.

Install crank pulley. Install hex nut assembly. Project complete.

This project is within the ability of most owners. Take your time on this. This is one of those projects that you can do a better job that the dealer.


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