Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Oil pressure sensor. 2006 2 let Duratec

Hi
I have an occasional "flickering" oil pressure needle. After a fairly long run on a hot day when idling the guage needle was going crazy flickering from one extreme to another.
In normal operating at 2000 rpm my oil pressure is at about 2.5 bar. At tickover 7-800 rpm the gauge is circa 1-1.5 bar. I think that these pressures are about par so I don't think I have a pump issue.
So my next thought was sender. I looked for the sender expecting to see a typical male sender in the side of the block somewhere.
However, not finding the obvious I googled it and was told it is adjacent to/on top of the oil filter and found this:



Am I right in thinking that the gizmo on the oil filter is the sender plus something else. I would have expected the sender to be the green electrical connector and the union it is attached to. However there, is no electrical wire coming out of the green connector only a wire coming out of the top of what looks like a diaphragm housing (silver).

Can one of our resident techies tell me
a. Have I found the oil pressure sender? If this is not the oil pressure sender, where is it.
b. If I have which bit of this assembly on the filter is the actual replaceable sender?
c What is the silver housing for (is it a diaphragm housing for something?
d. What is the part number I need for the correct replaceable ender for my engine

At a guess I's say the green connector (with no wire) is for a low oil pressure warning light (should come on with the ignition and go out just after the engine starts) and the diaphram gizmo is the variable sensor for the guage. This may be faulty and need replacing. Are you sure it's an electrical wire coming out of the diaphram and not a bourdon tube -- ie an oil-filled tube which goes up to the gauge?

My 2011 Duratec is exactly the same. I agree with Griffo’s suggestion above but confirm that it is definitely a wire coming away from the sensor rather than a tube. So the gauge is electrically operated. Before buying a replacement sensor, I would just check connections at both ends to make sure there isn’t intermittent contact as a new sensor can be anything from £50 to £100.
My guess is that the Ford Focus that these engines were built for would only have had an oil light so the sensor is added at some stage for Morgan’s requirements and as an after-market addition they come with the T piece to allow continued use of the oil light as well, if so desired.
I assume that when the fluctuations occur that all other gauges remain stable, so ruling out any issues with the instrument voltage regulator?

You have indeed correctly identified the oil pressure sensor and it is that whole silver round cylinder that screws into the tubular adaptor.

I had the same problem on my Zetec and got a new sensor from Merlin Motorsport. Demon Tweeks are slightly cheaper but Merlin have a bigger range and were more helpful.

Can't be sure the Zetec sensor is exactly the same spec the same as the Duratec but give Merlin a call. Mine was a VDO and yours looks very similar but there are thread variations.
Also variations on the earthing. Common ground if only 1 wire. You can also have a type with a second wire to a warning light but I think yours is the single wire, common ground with no warning light.

2 caveats

1. Use a good thread sealant as these taper threads can be a bugger if they start to weep.

2. On the Zetec, my problem actually turned out to be 2 fold. There is a pressure relief valve and mine was intermittently sticking which could allow very high oil pressures at higher revs so beware and keep your eye on the pressure even after you change the sensor.

Easy enough to get at and I think it has a VDO part number on it to identify.

Hi Ian

Not my strongest area but my understanding is cars with gauges have oil pressure senders that have a variable resistor that alters current as oil pressure increases/decreases and interface with the gauge.

Alternatively, for cars without gauges a simpler level/pressure switch is used. It monitors the oil pressure and turns off or on a warning light.

On the duratec I would surmise the Morgan stock engine had the simple sender (with the green connector). But the more ‘sophisticated’ silver pressure sender was added to complement the instruments. But, the original sender was retained (though not connected) possibly to aid “plumbing”.

I may be totally wrong, of course.

I’m Interested to know whose pressure sender is in use! Probably Caerbont.

Mine went haywire about 5 years ago on my 2010 4/4 sigma. I got a new sender/cylinder from Williams and fitted it - Solved the problem. But try cleaning the contacts first and give it a good blast with high revs for a couple of miles to see if anything has got stuck. When changing beware that on mine there is a brass step-down joint which is quite susceptible to damage - may be an idea to save time to order one of these at the same time. Luckily - in my case- my local garage rethreaded a step-down they had in -but not many places could be arsed to do that.

[img]https://photos.app.goo.gl/rD3VF6uC7scfpFoo8[/img]

Assuming this works...

A picture of my 2005 plus 4 sender unit.
Mine has a hissy fit every now and then, being doing it for around 20 years now. It resets itself if the car idles, eg traffic lights and is then ok for ages. I have stopped worrying now. I check the oil levels and otherwise ignore.
Sits at about 1.5-2 bar at hot idle and when it has a fit it shows an impressive 7-8bar until you let the car idle. Does eventually settle down if ignored.
Howard

Oh well, I shall give up on the photos.
H

Have a look to this thread (in French, sorry):

https://www.old-morgan-addict.fr/fo...amp;hilit=capteur+pression+huile#p110409


If the sender rehostat is broken, the pressure display increases. When you disconnect the sender, the pressure is displayed at the maximum. The needle goes full right.

Howard's photo makes sense of the wiring diagram which shows the Oil Press Sensor lead in a 4mm PVC tube