Hi, I need some help. My daughter is driving my 1982 240D at school, and she reported it suddenly developed a loud noise from the passenger side of the engine compartment. From her description I presumed was an exhaust leak. When I went to visit her today, I was expecting to confirm the problem, figuring the joint between the manifold and the exhaust pipe would be the culprit as that joint sees some stress when the engine wobbles around while idling or rolls over slightly under load.

Well, when I got there I confirmed it sounds like an exhaust leak, and when you load the engine, by putting the car in first, letting clutch out and keeping your foot on the brake, the noise gets louder and wheezier. If you heel and toe, and give it some gas abruptly, it makes three or four loud metallic clanks, then the engine speeds up the clanking stops and there is just a loud exhaust noise, but it is not coming from the manifold to exhaust pipe joint. As it was dark and I was on the street in front of her sorority house peering around with a flashlight, I could not confirm where the leak was coming from, and I could not figure out where the clanking was coming from either.

I checked the air cleaner mounts as I thought they might be gone again and that could be the clanking noise. While feeling around I found a hole on the bottom of the intake with air blowing out of it, and was curious if that is supposed to be there. It is on the underside of the intake casting on the firewall side of the casting. It seems to be about an eighth of an inch in diameter and at idle there is a steady stream of air coming out.

So, my question is where could the leak be and what is the clanking? Could the valves be making the noise? It seems to be a transient noise, which is not consistent with valve noise. Could the exhaust be hitting something below the car and the noise be "coming out" up near the manifold?

This car also has a tiring rear crankshaft oil seal, and I was wondering if there is anything that can be done, short of the procedure in the manual, which invlolves removing the crank to remove and replace the "rope" packing that makes up the seal, to keep the leak from getting worse? It is a slow weep now, with black oil wetting the weep hole area around the bottom of the bell housing and transmission. If she parks the car nose down, it doesn't loose much oil and when it runs it has normal consumption (quart every 1100 to 1500 miles) for a 240D with 276,000 miles. Even running I think most of the oil volume lost is coming out the rear crank seal.

Any suggestions will be greatly appreciated. Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)