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Author Topic: 1.6 and oil  (Read 150 times)
Morne
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« on: June 08, 2019, 10:26:18 pm »

The oil warning light in my 1.6 never comes on, as a result I am going through the system to find the fault/s. So far a few questions:

a) As per the photo, are these the min and max marks on the electronic dipstick?


b) On the 1.6 I saw a diagram indicacting that the oil pressure sensor and the low oil pressure switch are located together. However on mine it appears that there is no low oil pressure switch, and only the sensor for the guage on the dash. Where there versions which did not have the switch fitted?

c) As the oil light never comes, I suspect the control unit. I took it out and took it appart. It appears that somebody has alredy been in there. Please see the photo, and the red where I suspect a component has been removed. Are the any circuit diagram for this unit? Do anybody have a photo of the inside of the units?
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Anders Dinsen
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« Reply #1 on: June 09, 2019, 10:32:32 am »

Here's a photo of an oil level sensor unit. As you can see there's roughly the same components, but they're located differently on the PCB. I wonder why? Could there be a difference between the units for the 1.6 and the 2.2? I would think not, but perhaps? This is from a 2.2. The SN96525N is an anlogue IC for this special application, if you can find the data sheet, I'm pretty sure the diagram is from an application note.
« Last Edit: June 09, 2019, 10:41:37 am by Anders Dinsen » Logged

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suffolkpete
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« Reply #2 on: June 10, 2019, 11:31:57 am »

The oil warning light, by which I assume you mean the one in the cluster of four next to the clock, only signals a low level, which it does by measuring the resistance of the thermistor in the dipstick.  There should be an ignition feed to the lamp and the lamp is lit when a ground signal is applied from connector 3 on the control unit.  Connectors 1 & 2 are connected to the dipstick, 4 is an ignition live feed and 5 a ground.  If everything is working correctly and there is sufficient oil, the lamp should flash once when you turn the ignition on.  The max and min marks on the dipstick are as you say.
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Morne
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« Reply #3 on: June 10, 2019, 09:39:33 pm »

Thank you for all the information.

Question 1 solved : the correct reading of the oil level on the dipstick  Smiley

Question 2 & 3 : As per the attached figure 1, the pinout provide above of the connector for the oil level unit makes sense. I will check all the wiring from the dipstick to the unit, and then pull pin 3 to ground to check the connection from the unit to the indicator light. Unfortunately it is tricky to find a datasheet for the IC on the PCB. A few quick searches did not provide any results.

The reason I am also looking for the oil under pressure switch, is per figure 2 attached. This is from the Murena service manual, and show two paths by which the oil level warning light in the dash centre can be switched on. One is via the electronics dipstick and the electronic circuit(as per above), and the second via a low oil pressure switch on the engine. Where is this switch located?
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Morne
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« Reply #4 on: June 10, 2019, 09:53:09 pm »

The low oil pressure switch as per attached, appears to be located together with the sensor for the oil pressure guage. However as per my earlier photo, mine seems to be blanked off. Is it located at a different place on a 1.6 Murena?

This is where the drawing comes from:
https://www.ebay.fr/itm/Manocontact-de-pression-dhuile-Matra-Murena-1-6-et-2-2-L-Bagheera-Rancho-1979/191988798966?hash=item2cb36c95f6:g:PTMAAOSw9GhYk3ZT
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suffolkpete
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« Reply #5 on: June 11, 2019, 10:13:39 am »

The switch is shown in the official parts list, but on both the 1.6 engines I have it is blanked off as in your photo and there does not appear to be any wiring for it in the engine bay.  I think it must have been deleted as unnecessary, as has the low vacuum warning.  I wouldn't worry, its absence hasn't caused any problems in the 11 years I've owned the car and it is not necessary for the correct function of the oil level indicator.
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roy4matra
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« Reply #6 on: June 21, 2019, 10:48:12 pm »

The low oil pressure switch as per attached, appears to be located together with the sensor for the oil pressure guage. However as per my earlier photo, mine seems to be blanked off. Is it located at a different place on a 1.6 Murena?

This is where the drawing comes from:
https://www.ebay.fr/itm/Manocontact-de-pression-dhuile-Matra-Murena-1-6-et-2-2-L-Bagheera-Rancho-1979/191988798966?hash=item2cb36c95f6:g:PTMAAOSw9GhYk3ZT

On some Chrysler Simca Talbot models (the Tagora 2.2 was one) they did actually have a separate low oil pressure warning light in the instrument panel, and the low oil pressure switch was wired up and used.

However on the Bagheera and Rancho they often had a low oil pressure switch fitted but never wired up and the cars never had a low oil pressure warning, only a low oil level warning.  One reason the oil switch remained fitted was it had the correct thread to screw into the block whilst the oil pressure sender did not!  So the oil switch was simply holding the tee-piece into which the oil pressure sender was fitted.  This often happens in large organisations where something that has been done for a long time, doesn't change unless someone takes a close look at things. (usually to do with cost cutting!)

When they got to the Murena, someone did decided it was a waste of money to keep fitting a switch which was never being used, and so they finally fitted a banjo bolt to hold the tee-piece in place.  Ideally they should have changed either the oil pressure switch or the thread in the block so they matched and then they could have fitted the oil pressure sender directly into the block.  But it was probably decided at the time that to change either was not as cost effective as simply using a banjo bolt.

The Murena, both 1,6 and 2.2, never had a low oil pressure switch.  However, with a low level warning and an oil pressure gauge it really is not necessary.

Roy
« Last Edit: June 21, 2019, 10:53:41 pm by roy4matra » Logged

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