02GF74 Posted October 12, 2006 Share Posted October 12, 2006 Reducing the pulley diameter is not a good idea due to the strong possibility of increasing cavitation damage. Even with the standard pulley setup the EFI water pump is renowned for cavitation damage to the ali timing cover (the pump housing). The area that suffers most is right behind the impellor around the two outlets. Speeding up the pump will only worsen this situation.This effect is more pronounced when no coolant has been used in the engine (just plain H2O)………. But it is still a problem even with added coolant. I have yet to find a EFI time cover without some indication of this type of damage. Ian Can I politely ask how are you qualified to know the timing cover is damaged due to cavitation? Do you work in this field, heard it from someone else or speculation? I am not saying you are wrong or anything, just curious. My knowledge on cavitation is pretty limited - it happens when you try to push water so fast that the pressure created causes instanteantous vaporsisation (ok, that may not be right but is close) and the effect is that instead of pushing against water e.g. a propeller, it is pushing against little bubbles of gas so is less efficient. I can also imagine, and this is guesswork since I have not looked into this, that the vaporisation causes tiny explosions, and it the shockways from these that over time cause fractures in the metal. (specualation since I do not know the type of damage you mention). As I said in the original post - but re-read it and I think I used higher instead of lower - me bad ) - the rpm that cavitation would occur would be lower if you have a smaller water pulley. by the time the EFI engine came out, I would imagine Rover had quite a few years of data/failures/experience to know what size pulley to fit on the water pump for the max. rpm of the engine so am a bit surprised that this problem occurs. Is it just the RR EFI or did it affect the carb P6 and RR? All this means is that the engine shouldn't be revved as high so in the case of the orignal poster, that should not be the issue since the hot engine syndrome is occuring offroad at low speed and probably at lowish rpm, certainly shouldn't be redlining the engine (speculation on my part). Quote Link to comment Share on other sites More sharing options...
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