I think the biggest threat there is neglect of the cooling system causing the stamped blades to rust away completely. I have seen water pumps with stamped vanes that were totally GONE after the owner left the coolant way past expiration and only came in once the car started overheating.

I wouldn't sweat the sheet metal impeller. Obviously a cast one would be better but it's not a deal breaker. I think most of the critical difference is in the effects of corrosion in a neglected system - it's going to take longer for a cast impeller to corrode to the point of failure.

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Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

There is also the sheet steel Freeze/Core Plugs in the Block to worry about if the cooling system is neglected; at least when you look at a pic in the parts catalong they look like they are steel. And, a Water Pump is a lot easier to change then the Freeze/Core Plugs.

Also notice that that some of the under the Hood on the Fire Wall Heater Tubes are Steel.

8 years ago when I got the Car the Bypas Hose was seeping so I changed that and I also changed the Radiator Hoses and I believe I changed the Coolant at that time. Since that time I have done nothing to the Cooling System.

On the Volvo Diesel I have not done anything to the Cooling System since the Water Pump was replaced back somewhere around 1993.

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84 300D, 82 Volvo 244Gl Diesel