Replacing either of the rear cam seals is not terribly difficult. Just make sure the seal is not installed in reverse and use a large socket to tap it into place. -- remember where each plug wire goes.

To check for positive pressure in the crankcase, remove the dipstick on a warm engine, cover the opening with a cutoff laytex finger or balloon, and if the laytex inflates you have positive pressure. Of course, don't let the laytex get sucked into the opening.

Or get a vacuum gauge and plug it into the vacuum tree for real good readings.

--
My name is Klaus and I am a V♂lv♂holic

Can't help you with the rear cam seal. Never done one.

However, you may still be able to stop the leak unless it's poring out or the seal is dislodged. First, drive the car for at least 15 minutes to get it good and warm. Then pull the oil dipstick. If she smokes at idle then you have a problem somewhere with the breather system.

Do the 98's have flame trap screens? If it were my car, I'd first throw away the screen and replace the flame trap and hose. Then clean the EGR (if it has one) and finally replace the breather box and vacuum hoses under the intake.

Then give it some time to see if the oil leak goes away once you have reduced the crankcase pressure. Changing to synthetic oil can often make seal leaks worse initially. Once the synthetic has had some time to do its magic on the seals - cleaning and restoring their pliability, the leak might very well dry up and go away.

The rack seals leaked on my 95 855. After changing to Mobil 1 synthetic ATF, the leak got worse. Now, the good news. After a month or two the leak dried up and disappeared. It's been over 2 years and the leak hasn't returned...:)

P.S. - I was also able to stop a rear main seal leak on my 240 by reducing the crankcase pressure.

Good luck!
J

--
95 855 GLT Sportwagon 220k, 90 244 DL 300k+ - after 11 years has a new home