Dear Robert,
I am responding to Martin Podeu's overheating problem in his recently-acquired 3L. My current 3L came with a severe overheating problem.

There were several causes operating together. (1) The water pump bevel had been fitted the wrong way round. It can go in either way, but in one direction, there is nothing for the water pump shaft to engage with. Without the pump, the engine will overheat badly. This was not the first cause I investigated, because it is very obscure, but it is fundamental. (2) Water circulation. Obviously try flushing the radiator in both directions. In my case, someone had fitted the water plates with cardboard gaskets that had not had the centres cut out. Hence, lots of slowly disintegrating cardboard fibres. The pinchpoints were the return water gallery behind the offside water plate, and the entrances into the upper water gallery on the near side. Having got those cleared, I still had problems. (3) Petrol. Make sure it is 97 or 98 octane. (4) Check the carburettors. If they are slopers, they may need new jets. Also check the needles. They should have their size stamped on the top of the stem, albeit faintly. Engine temperature is very sensitive to the correct jet, and a jet that weakens the mixture will cause overheating. (5) Compression. I rebuilt my engine because of poor compression, and the difference in emperature control with good compression was very striking. If you do rebuild, you will check the valves as well. (6) Finally, the problem that was the first I dealt with was, believe it or not, a cracked float. This had the effect of making the engine run rich (because the float sank all the time). This produced lots of carbon, and dribbling from the carburettors was constant. Indeed, it was a wonder the car hadn't caught fire.

Only after checking all these should you even contemplate a new radiator. Unrelated to overheating, but of general relevance, I would now always partially strip an engine in any 3L I bought unless its provenance was impeccable or it came with strong warranties. The reason? When I finally undertook my rebuild, I found the crankshaft had been overground, and the rear main was pitted in the wrong places; and secondly, one of the original con-rods was cracked in two places. It was only a matter of time before collectively they gave serious trouble, and if it is a matching numbers engine, value-destroying trouble.

Hello Martin, you have checked everything that I would have checked. Since you bought it "some weeks ago", I assume the dealer or individual that sold it to you had the same problem. I suspect you contacted the seller and the seller could not solve the problem either. A blockage in the engine circulation would be the next guess. You might put some dye in the water and see how fast the dye returns. But I cannot tell you how fast that should be as I have never run that test. Do you have the BDC's Technical Facts of the Vintage Bentley? You should not need a new radiator and no they do not normally run hot. I have a 3 Litre here in Houston, Texas and it really gets hot outside but the engine runs fine with no fan. Let me know how this turns out. – Best wishes.

The thermostat may need adjustment. Refer to The Technical Facts of the Vintage Bentley. The pipe that goes from the RH side of the engine block to the water pump may be clogged. Remove it and see that this is clear.