I have suspected an exhaust leak in my 300D (W124) for quite some time now. The engine compartment likes to dirty itself even though the engine has no blow-by, and I can sometimes smell diesel exhaust in the cabin. Well, I think I finally found the leak. I started my car with the hood open the other day, and a nice little puff of smoke came off of the engine by the exhaust manifold.

Upon closer inspection I found that the leak is coming from where the manifold meets the head at either cylinder 4 or 5 (near the front of the car). The head has a nice layer of soot on it in that area.

I have several questions regarding this leak. First of all, how urgent is this repair? I am low on money at the moment, but if ignoring this repair now will cause more expensive repairs later I will bite the bullet and pull out the platinum card.

Second, how expensive is a repair like this? I want to explore all options before I take it to my mechanic.

Perhaps this is something I could fix myself down the road sometime, but right now it seems a little over my head.

Any advice?

__________________
Ben

The MBs:
1976 300D (W115) - 330K and still going (sort of)
1991 300D 2.5 Turbo - Sold at 221K
1983 280SEL - Sold at 206K
1981 300SD - Sold at 232K

Ben;
Engine cylinders are numbered from #1 at the front to #6 in the rear.
If the smoke originates at the front of the engine look closely at the stainless steel coupler that connects the front and rear manifold parts.
As far as urgency,If you can smell exhaust in the cabin of the car you are also getting a good dose of carbon monoxide.(This demands attention right away)
M.F.

You can probably do this repair youself. Get some liquid wrench or equivalent and spray the crap out of every exhaust fastener on the exhast mainfold and exhaust pipe flange that connencts to the exhaust mainfold. You probaly have exhaust mainfold gaskets that must be purchased at the dealer or here at Fastlane. Try and loosen the bolts after spraying with liquid wrench. It they dont budge keep spraying and soaking with liquid wrench. If they wont budge take it to a pro. You don't want to break of one of those bolts.
I also would suggest to carry a working carbon monoxide detector in your car temporarily until its fixed so you know if you are safe.

__________________
1990 190E 2.6
1996 Grand Voyager 3.3
1985 Mustang GT 5.0 5 SPD
1982 Suzuki GS 750T

Well, it turns out that the gasket is bad AND some of bolts were loose. I tightened the bolts and the leak is not as bad. I can't hear it anymore, but I can still see some smoke escape if I overfuel my engine while watching the manifold. I guess having those bolts loose isn't too bad since I know I won't have a tough time removing the manifold.

However, I will be running quite short on free time for the next month or two. This leak has existed for quite a while now. Am I running a big risk of permanently scorching the head by not fixing it right away? I would really like to hold off on repairing this, if I can. If I am risking damage to my engine head then I will just cringe a little bit and ask American Express to have it fixed for me.

__________________
Ben

The MBs:
1976 300D (W115) - 330K and still going (sort of)
1991 300D 2.5 Turbo - Sold at 221K
1983 280SEL - Sold at 206K
1981 300SD - Sold at 232K