60Patrol

I have a SD33 NA Diesel engine fitted into a Land Rover Defender. The timing is correct, the fuel pipes have been renewed and no air locks (fuel filters cleaned). The throttle (venture) is set correctly and the air intake manifold has no leaks. The throttle cable to the venture is free moving. (all check in accordance with the Nissan SD33 workshop manual).   Having said that, there is a problem. When the engine is started and the engine is cold the engine runs perfectly. But when the engine is warm and the engine is reved up the revolutions stick and sometimes drop down to idle and sometimes hold where they are.   Any ideas as to what could cause this issue would be appreciated.  

I had a similar problem on my SD 33 engine, which was corrected by removing the thermorstat valve on top of the water pump. I live in a tropical country so I don't need it, you may have to replace it if you live in a cold climate. hope it solves the problem. cheers sal