Mi16 Sudden Low Oil Press - Major Engine Problem Or Something Else

[sport1901966 8]

Hi all,

 

I am totally stumped with the latest issue (getting fed up now as it should be on the road and is wasting me tax and insurance money ). Prior to the MOT and purchase of tax and insurance it was running great, but since paying out that money its throwing more problems at me.

 

Firstly it was running a bit hot (needed fan on permanently) so I went to great effort fabricating up a whole new cross member to mount the rad lower and more upright, along with removing the bumper blank and fitting a 12" slimline fan, all to improve air flow. On starting the engine to take it for a test drive after doing all this the coolant level warning light was on (further investigation shows the sensor is dead) and more worryingly the oil pressure gauge is showing no pressure at all. I can't swear it was fine by the end of the last journey, but it was definitely fine during the last journey.

 

The slightly odd thing is that the secondary oil pressure switch and light I fitted (calibrated to activate at 25psi) is not lit - suggesting pressure is at least.... you guessed it - 25psi!

 

I have removed the gauge sender (what a b**tard of a job) and tested it by connecting it to the wiring to the gauge in the car, and earthing its body whilst subjecting it to pressure using a footpump. When doing this the gauge registers pressure up to about 8 bar, exactly as would be expected. This then indicates to me that the wiring in the car is fine (I had hoped I had just disturbed the brown plug), and that the sender and gauge are fine. I then used a multimeter to test the resistance between the threads in the block to the battery negative terminal and there is no resistance, again as should be the case.

 

So, basically, the whole oil pressure gauge wiring/sender/gauge/earthing are fine.............. Bo***cks............ That must mean that the bottom end is gone. However going back to the secondary warning light and sender I fitted, there is at least 25psi pressure, which the dash gauge doesn't register.

 

Is my engine f**ked - only done about 70 miles. Or is there something else I may have disturbed when remounting the rad etc. Or do I have the most bizarre electrical gremlin ever (considering all related oil pressure gauge components and wiring check out)?

 

Help!

Edited July 28, 2011 by sport1901966

[jackherer 543]

Does your oil pressure light come on with the ignition and go off when the engine starts?

[Anthony 1,003]

Does the oil pressure warning light come on with the ignition, and go out when you start the engine as it should?

 

25psi is about quarter on the gauge and should definitely register. Indeed, it's high enough that I'd expect the light to come on with hot oil at idle.

 

If you're worried, get hold of a mechanical oil pressure gauge - you'll get a very accurate picture of oil pressure then, and realise just how bad the standard gauge/sender is...

[sport1901966 8]

Yep the warning light is on when the engine isnt running then turns off once the engine is started.

 

I may have to get a mechanical gauge. Can you recommend any particular one? I assume a T-piece or adaptor will be needed?

 

Thanks guys

[sport1901966 8]

Problem solved!

 

I can't believe how ridiculous it turned out to be!

 

I shall use pictures -

 

Below shows how the wiring was connected, obviously the yellow connector has been cut off but originally went to the dash gauge. In this condition I got no oil pressure indicated by the gauge.

 

 

And the following image shows how it was set up to test (I needed to extend the wire out of the engine bay to hook the sender up to the footpump). The main point to note is the yellow connector was used on both occasions, and that the spade terminal on the sender is the same as the one I used in the wiring extension.

 

 

Well it turns out that the yellow connector had a bad connection to the sender, which was resolved when using the extended wiring. As such when I refitted the sender but used the wiring extension, the gauge showed pressure as per normal.

 

I am astounded as firstly, that yellow connector has worked perfectly for over 70 miles of driving, and secondly it only decides to stop working whilst sat on the driveway. BTW I did disconnect and reconnect it in the troubleshooting process, it wasn't just loose from when I was remounting the radiator.

 

Anyway, I'm a happy man. Thanks for the input!

[ORB 227 1 Cars]

Ha!

 

I have an indicator connector that likes doing this!

 

Happy it's not a bottom end though!!

Edited July 28, 2011 by ORB

[sport1901966 8]

Ha!

 

I have an indicator connector that likes doing this!

 

Happy it's not a bottom end though!!

 

Yea indicator and sidelight bulb holders are classics!

 

Cheers, I am too!