One more thing to watch out for when shopping - PeachParts Mercedes-Benz Forum

Jeremy5848 · #1 11-04-2008, 10:56 PM

Visited my local mechanic just to say hello. He had a 1980 300D NA in the shop with the head off. Turned out it had been purchased by a local guy for his daughter, attending Sonoma State, as safe and reliable transportation. What they didn't know was that a PO had cracked the head in several places and, instead of replacing the head, had "pinned" the cracks and reinstalled it, then dumped it on the new owners.

The girl had called the mechanic to say that she was coming in, the car was overheating. When she arrived, the wrench was surprised to find the engine idling beautifully, even though the temp gauge was off scale high. He found the radiator cold to the touch – no coolant at all! but the block measured 300 (F or C, I forgot to ask) on his infrared meter. Apparently, the pinned cracks had leaked small amounts of coolant into the combustion chamber and without the driver realizing it, eventually drained the cooling system. After the engine cooled, the mechanic put some water in it but the leakage (combustion gases into the coolant passages) blew it out as fast as he poured it in so he went on to pull the head. Daddy is now searching the junkyards for a good NA head – apparently he is limited to just two or three model years for this engine.

I was not aware of this pinning procedure and see it as a good way to get burned on a used car purchase. If the leak is very small, there's no way the typical pre-purchase inspection will reveal it. The mechanic showed me the head, which had been pinned in at least three places. Anyone ever seen this type of repair before? For those who, like me, have not, the procedure is to drill a hole at the end of the crack and then press in a steel pin. It stops the crack from growing, at least for awhile.

Jeremy