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Old 09-17-2013, 03:25 PM
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Join Date: Aug 2008
Posts: 97
W123 oil leak!

So, I've been driving my W123 for 11 years now, its at 314K miles. I do not drive it in the summer since the AC went out several years ago, but it sees work from say now, September, until May or June.

Two years ago I made the messy mistake of topping off the oil and not replacing the oil cap, and then driving the car a bit of a distance. I noticed a bit of oil coming up over the top of the hood and realized my error, and pulled over and put the cap back on. What a mess though.

The car had always leaked some oil, and after this I had to clean up under the hood, which I did with a degreaser on the side of the block and a good rinse.

Since then, it leaks a bit more, too much to park on the driveway and I keep cardboard under it in the garage. Strangely, even with what looks like a lot of leaking, it doesn't lose oil volume in the motor like it looks like it should, but then again oil leaking from a car is like a bleeding wound on the face-it looks way worse than it is once its cleaned up. I keep it topped up so its safe to continue operating. I'm worried when I cleaned the oil off the block I aggravated some gaskets, or cooled them when they were hot, and now they don't seal well. Oil pressure is still good, and it starts and runs great.

There is one leak to the front driver side and one to the rear of the motor near the bell housing. The valve cover gasket is maybe 6 years old, which clearly started leaking back then. No other gaskets have been replaced while I've owned it. I've been doing some research and have discovered the wondrous world of rope gaskets, which I do not anticipate replacing anytime soon. I would like to get a few more years out of this car, though, and am planning on new tires (probably the last set I will see), and I'm replacing the brakes again.

At any rate, after my research I was considering a new transmission filter, along with a new oil pan gasket and a good look around at a trustworthy shop, like at the oil separator. If there is still considerable leaking, I guess I will live with it. Any other suggestions I might be missing? Turbo oil intake leak?


84 300D, 303K
71 MGBGT, ?K
96 GMC C1500, 115K
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Old 09-17-2013, 03:42 PM
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Join Date: Jul 2008
Posts: 3,740
Guessing if the valve cover gasket is six years old it hasn't had a valve adjustment for sometime......I would do both....

Hard to tell where the oil is coming from but the most common causes are valve cover gasket and oil filter housing to block gasket......I thought my rear main seal was leaking because of the oil on the bell housing, but when I changed the transmission filter.....I noticed it was all because of the oil filter housing gasket....
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Old 09-17-2013, 04:17 PM
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Join Date: Aug 2012
Location: Philadelphia, PA
Posts: 490
Check the lines to the oil cooler and check the cooler itself as well.

Also, it's not an oil leak. It's an undercarriage rust inhibitor!

Phil Forrest

1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson
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Old 09-17-2013, 04:38 PM
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Join Date: Dec 2005
Location: Carson City, NV
Posts: 3,789
Originally Posted by cooljjay View Post
Guessing if the valve cover gasket is six years old it hasn't had a valve adjustment for sometime......I would do both....
After that replace whatever gaskets you know are leaking. Then, starting with a clean engine, run the engine and observe to determine if there are any additional leaks, where they are coming from, and if they are serious enough for you to want to fix.

Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 367,xxx miles
08 Triumph Street Triple 30,xxx miles, lowered 10mm in front, Pirelli Angel GT tires, EBC HH brake pads, otherwise stock.
88 Jaguar XJS V12 93,xxx miles. I should be in the garage now.
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