"B" Series Beware
 

The first thing I tell any new owner of a Rolls Royce "B" series motor is "CHECK THE WATER JACKET COVERS!"
These cover plates are cast out of Aluminium, round ones along the induction side, (2 on a B40, 3 on B60 and I assume 4 on a B80) rectangle ones back of block and back of head.
The round one shown appeared intact: until I gave the Champ a pressure wash, wondered where all the green stuff on the concrete came from.
Got caught again with the Humber on its first trip to Corowa when it dumped its load of water in one hit out of one of these covers.
Had a periodic loss of coolant from the Humber for the last 6 months, finally tracked it down to the rectangle cover on the back of the block. Hairline crack. The cover on the back of the head also starting to show the rot, so it will be replaced as well.

Have been told in the past that these covers act as sacraficial anodes, but after talking with Australias part time Champ Diff Guru, and full time metallurgist, I now discount this theory, and happily replace these plates with Brass or Stainless Steel.
Certainly a good argument for using good an anti corrosion inhibitor .
Of course it is easy to say check the plates, but the rearward ones are a pain to get at (in the Humber), feels like I have pulled half the truck apart to get to it.
With plates of it is also a good oppourtunity to stick the garden hose in and flush some crap out.
Rich.

Rich,
These plates suffer no more than the old style steel welch or core plugs in engine blocks. The aperture they are blocking being part of the casting process. The build up of sediment, sludge, etc in the water jacket, often covering any plugs in the lower part, encourages corrosion. Often in hotter climates, owners do not use antifreeze/inhibitors and this encourages sludge and corrosion. The amount of evil crap I have flushed out of some blocks is unbelievable.

I hear you Richard, I'm still flushing after two years, think I have a bottomless supply of red crud.
Rich,

So I see !

Last year I had to restore a jeep which had been laying in a museum for many years, but prior to that, had been driven from India to the UK. When I went to survey it initially, the warning signs were stains all over the engine compartment. It was unbelievable the amount of scale, sludge, etc that I had out of the engine, mind you, had to strip it out and turn upside down, the rad was severely blocked as well. My suspicions that it had been filled with ditch water during its travels were confirmed as apparantly it suffered overheating problems in India and a failed waterpump in Iran.

Surprised you did not find a few yabbies in the bottom of the radiator as well.
The point you make about the welch plug is a valid one. It's just that you expect them to rot out eventually, while those nice big plates on the "B"'s look so solid, and lets face it, I did'nt know what they were for, until the first one failed. Hence my warning for those new to these beasties. Hmmmm Are there any plates I have'nt mentioned? 'cause that means I don't know about them, and I probably need to...
Rich.