I distinctively remember someone once writing that they drove their 87 300D W124 300 miles with a cracked head..to Seattle or some place like that. Can someone refernce or repeat this story? Reason is I just did 40 miles on my 300D 85 with no water pump (PLEASE DONT ASK ME TO EXPLAIN....) and I am wondering waht my damage is..maybe none?

Sure you can drive a 603 with a cracked head, the cracks take a long time to get worse and cause a problem so their are probably cracked heads with thousands of miles on them. I think the usual symptom is coolant being used and pressure in the upper rad hose in the morning. As long as coolant isn't mixing with the oil and them temp stays down I don't see why you couldn't drive it.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Mine was driven at least 15,000 miles with a cracked head. For most of those, the only sign was cold pressure in the coolant system, but for the last few thousand it was also using coolant. The only big risk you run is if it allows enough coolant into the cylinder to hydrolock it, then it is new engine time. As long as the coolant usage isn't too severe, you can get by for a while.

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Keep everything as simple as possible-but no simpler--Albert Einstein

I drove my '83 300D 50 miles at expressway speed with only the aux coolant pump circulating water. No damage. Those old engines have iron block and heads and are super tough. My engine got real hot but did not quit. That was probably 20-25k miles ago and car still runs fine. For the record, the pulley had fallen off the alternator. My own fault. Car has about 380k miles on it now.