Oil Pressure

[kiwi1973]

I am beginning to suspect this may end up a bit of an odd one. Yesterday I had the oil pressure light coming on at idle and going out with revs - not unlike others have encountered and discussed in other threads. But what I couldn't work out from reading those other threads (which all pointed to the oil pressure sender being located on the block near the oil filter and turbo) is why my oil pressure sensor is sitting on top of the vacuum pump?! More odd is that when I look in the Mitsubishi manual there is no oil pressure sender shown on top of the vacuum pump, making my setup look odd.

I recall that last year when I got fuel contamination and had all the fuel injection replaced they had some issue working out where the wiring to the oil pressure sender was meant to go and they ran some new wiring to where it is now situated on top of the vacuum pump.

I have two questions - can anyone confirm that this setup is wrong. I.e. does anyone else have a pressure sensor on top of their vacuum pump as shown in the photos I have attached?

The second point is that in the photos you can see oil is weeping around the pressure sender. I suspect this is why I have the oil pressure light flicking on. I.e. nothing really wrong with the engine or oil pressure in reality, just issues with sensing. Engine is sounding and performing just fine.

[kiwi1973]

Just to update my own post. Upon discussing with the diesel injection specialists who replaced my entire fuel injection system after last year's fuel contamination related failure they confirmed that they hadn't been sure where to put the oil sender. They claim that on Gen 3's it was located on top of the vacuum pump (I'm not sure they're correct) and so they mounted it on top of my vacuum pump. Initially I was concerned whether it was appropriate to relocate it away from where Mitsubishi had it, however as I now recognise an oil sender is nothing more complex than a switch (activated at a predetermined pressure level) then I can't see an issue with it on the vacuum pump and it certainly is easy to access there. I haven't replaced it yet, but it is failing and I'll get on it this week. There doesn't appear to be any genuine issue with oil pressure, just a failing sender worth about $20.

[erad]

Kiwi:
I have had a look at the Russian CD copy of the W/S manual about the vacuum pump. There is an oil pipe feeding the vacuum pump, but no return. Therefore, any net oil flow must be what leaks past the vacuum pump seals - presumably not very much. You may get some sludge buildup in the pipe which could affect the way the switch operates. I haven't even seen my vacuum pump (I know it is there), but maybe if you could disconnect the oil pipe and flush it by running the engine briefly, or totally remove the oil pipe and clean it - this may improve the situation. Certainly it would give you more peace of mind where you intend to go.