The aluminum coolant passages on the B280 are in great shape, which isn’t exactly a surprise with such a low-mileage motor. Once I replaced the split water pump I reassembled it with a new thermostat and had it ready to go and was feeling good. As I was test fitting the radiator and hoses recently I noticed there is a tiny difference between the two thermostat housing outlet diameters. Which is pretty obvious here with the B28 setup on the right and the B280 on the left.
For some reason the B280 has a much smaller diameter outlet than the B28F did or the Eagle Premier 3.0 does. Maybe the smaller outlet combined with the higher pressure overflow cap in the 760 cools better than the B28 setup did? This goes beyond my knowledge of cooling system design. But since I am using a 260 radiator and 260 radiator hoses I need to replace that outlet with the bigger one. Easy job. And since I have one lying around why not use the nice Eagle housing with its fancy plug wire retainer? Looks nicer in my opinion.
Only downside I can see is it needs more aluminum corrosion cleaning, which I’ve become rather practiced at thanks to the Mercedes.
After a half hour or so of wet sanding the bulk of the corrosion is gone but there is still quite a bit of pitting.
Another hour or three of work and I’m almost ready to say it is good. Minor pitting left but not much that I can really feel with a fingernail.
The flange on the water pump side is pretty good. Some light corrosion but nothing too bad. I used a piece of glass with some value lapping compound to clean up the bottom some while still keeping it flat.
And then it went back on the motor and I’m ready to continue with assembly.
