I bought a new sender and had it on my todo list for the next oil change, assuming that removing the sender would require the engine to be free of oil.   However, my mechanic stopped by recently and told me that it can be changed at any time, and even changed it for me quickly.

I assumed that would be the end of it, however the light continued to come on randomly, and even sometimes came on at idle.  Coming on at idle made me think that maybe there could be more to this, so I decided that I wouldn’t drive the car until I tested the oil pressure properly.

Of course, Citroen didn’t use a common sized oil pressure sender, so none of the adaptors in my mechanical oil pressure gauge would work.    I still had the gauge from the saga with my 300SE a few years ago.

I looked online for adaptors.  They were not expensive, but most of them seemed to come from the UK with shipping higher than the actual adaptor.   I eventually found a local one.   The sender unit is a male M10x1.5 thread.   I found one that provided two ports, one a more standard size and the other for the original sender.  I purchased it.

When it arrived it looked pretty good, but there was a problem.  There isn’t a lot of clearance to get this larger adaptor in, and while I could get the adaptor in, I couldn’t then get the fitting for the mechanical gauge in.   I tried a few times, both from the top and the bottom.  Since the gauge was out of the car, I couldn’t start it, so I used a jack to lift the car to try from the bottom.  In my ineptitude I managed to let the car fall off it and put a scratch on the side.  Luckily its not that visible from the side and mostly hit the bottom.

That left a sour taste in my mouth, so I decided to just order one of the smaller adaptors from the UK.   It took a few weeks to arrive.  It was much smaller and doesn’t have provision for the current sender.  That wasn’t an issue for me as this is a troubleshooting step and not a permanent install.

After all the time wasted with the old adaptor, I had the new one installed quickly.   Its smaller size making it much easier.   I soon had the gauge installed as well.   Starting the car, I had good news.   about 4.5 bar of oil pressure, or 65psi.   It would rev to about 70psi.

I let the car warm up a bit and the pressure stayed good.  A I then took it for a drive around the industrial estate where I keep my cars. I was never able to get the pressure to lower even at 4,000rpm.   I then let the car idle for a while until the electric fan came on and the oil was good and hot.   The lowest pressure I saw was about 2.5 bar or 35psi at idle. I consulted the workshop manual, and the specification for the oil pressure is that it must be at least 3.8 bar (54psi) at 3,000rpm with the oil at 60 degrees. (assuming 20/50 oil, which I use).

At this point I was pretty confident I didn’t have an oil pressure problem. I took the car for a drive again with a warmer engine and hot oil pressure was still good.   I also noticed something else that really sealed the deal.   At one point, the oil pressure light came on when revving the engine.   This should not be possible as the sender is not plugged in.

Its possible that this is related to the circuit board in the instrument cluster.  I know mine already has an issue as I had to bridge the connection for the illumination.    It may also be to do with excessive voltage at high RPM.   I’ll put a voltage gauge on the car at the same time so I can check.

This test, has given me much more peace of mind that there is nothing actually wrong with my car.   Citroen DS engines are very tough.

The post Citroen DS Oil Pressure light appeared first on Classic Jalopy.

I was advised on the ozBenz forum that another possible cause was the oiler tube for the camshaft coming loose.   The oiler tube is held down by a couple of bolts that if overtightened can strip the threads.    Since I don’t have a lot of history on the car, but the head was off 10,000km ago, it was a good test.

This last oil pressure troubleshooting was also something I could do at home.   Its a fairly simple matter to remove the cam cover on the M103.   Unlike on the M117, there are no fuel lines etc in the way.    Unfortunately my results were the same.   This oiler tube was in fine condition and so not my problem.

The photo below shows the engine with the cam cover removed.   The engine is actually running in this picture, and you can see the oil pooling at the bottom of the picture before it drains back into the sump.   I’ve never run one of these engines without the cam cover before, so I have no comparison, but I could see a steady stream of oil dripping over the cam lobes.

The engine ran like absolute crap without the cover.   I assume due to vacuum leaks due to the disassembled state.   In any case I have gone as far as I can at home.   The car will go in to a mechanic in a couple of weeks.     I am hoping there is not major damage and an oil pump change will fix the problem.

The post More M103 low oil pressure troubleshooting appeared first on Classic Jalopy.

I hooked up the gauge and sadly the results were much the same as the dashboard gauge.   The mechanical oil pressure gauge I purchased has a number of fittings and one of them was correct for the M103.   It also had a quite useful elbow connector.

It is much easier to attach it with the oil filter removed.   Don’t make the same mistake I did, and not attach the filter properly!  You’ll end up with a lot of oil on the floor very quickly.

As can be seen by the readings below, they are not what they should be.    The first one is immediately after start up, and the second is after a couple of minutes of running.

As can be seen from the next photo, there is oil at the top of the engine, so something is working properly.

I also made a short video about taking these readings.   Still not very good at this video thing, as the gauge itself is not readable, and when looking at the senders, they are out of picture, but plenty of room for improvement.

As I mentioned on the video, I will take the car down to my workshop and remove the cam cover.   From there, I should be able to inspect if the oiler tube has come loose.   This was suggested to me on a thread in the ozBenz forum.

The post Testing M103 Oil pressure with a mechanical oil pressure gauge appeared first on Classic Jalopy.

The M103 oil pressure sender can be found on the side of the oil filter housing at the back of the engine.   Most of the threads you’ll find on the various forums are referred to the W124.   Apparently on the W124 space is tight and it is a paint to remove the sender.   I can only imagine how hard it must be on the W201 then.     On the W126 there is loads of space, as can be seen in the photo.

With the right spanner, you could probably remove it with the oil filter in place.   I elected to remove the oil filter first.   It made it dead simple to disconnect the wire, and then unscrew the sender unit with a 17mm spanner.    As can be seen in the photo below, there is loads of room without the oil filter in the way.

I went with a new VDO sender.  VDO are the OEM brand.   There are also Meyle sensors availabe, which are much cheaper.  Meyle is a brand I try to avoid.   There was somebody on one of the facebook groups complaining they have replaced two sensors in as many years.  I bet they used Meyle.   Comparing the new M103 oil pressure sender, the original one was still on the car.   It was dated 7/86.   I put a new 9/19 unit on.   Still made in Germany.

Re-installation is even easier than removal.   There is a little washer that goes back on.  In my case it had remained stuck to the housing.   The new one is certainly a lot cleaner!

I then fired the car up.  I expected to see the oil pressure reading jump to three.   But it didn’t.   Instead, the pressure was the same as before.   Around the middle of the gauge after a cold start.

Clearly there was nothing wrong with my older sender.   I think my next step will be to take the car to a mechanic to hook up a mechanical oil pressure gauge.   This will eliminate the wiring, gauge etc and check the actual oil pressure of the car.

I can think of a few possibilities in order of likelihood.

• Oil pressure relief valve stuck
• Faulty Gauge
• Bad wiring to gauge or sender
• Worn Oil pump

I think the oil pressure relief valve is built into the motor on the M103, so not a quick change to see what happens.  The mechanical gauge will at least determine if there is a problem.

The post M103 Oil pressure sender appeared first on Classic Jalopy.

The other cars on the drive were rather varied.   There was a Ferrari 458 Spider, an Audi SUV, a race prepped Toyota Yaris and a couple of other Mercedes including a C63, C250 and E400 Cabriolet.    It was quite amusing to be in a convoy in my 300SE following a C63 and the Ferrari.   I think the power difference was probably about 500hp.

It is also my first drive in the 300SE now on historic registration.   I now no longer have any cars on full registration, and will rotate the 60 days I have available on each car.   The roads were quite good even in the wet.   The view from Mt Kiera was also quite nice over North Wollongong.   The W126 does quite well for a softly sprung limo.

After leaving the meeting point I observed some strange behavior on my 300SE’s oil pressure gauge.    The normal behavior is the car idles above 1 bar when hot and pegs when accelerating.     All of a sudden, the reading was negligible at idle and rose very slowly on acceleration.    At this point I was not sure if I really had low oil pressure.

My first step was to stop and check the oil level in the car.   The level was on the low side, just above the low mark.   I added some extra oil and it made a very slight difference.   Even with the much lower gauge reading, the pressure was just inside the spec in the owners manual.   Based on that, I kept going on the drive.  The car was running really well and I was starting to think it might be a gauge problem rather than an engine problem.     Just in case I was easy on the engine and kept the revs below 3500.

When I got back I did an oil and filter change.   The car was due for one and this would eliminate contaminated oil. It’s been a year and about 5,000km.  The dipstick looked fine, but there was an outside chance the oil was contaminated with petrol or coolant.   As a tip, trying to do an oil change quickly just results in a lot of spilt oil.

After the oil change there was very little change to the oil pressure gauge reading.   Next was to run the engine without the oil cap.   I wanted to see that oil was getting to the top end of the engine.   I could see a steady stream over the cam lobe.   This made me think that I have good oil pressure.     If this is correct, then the issues is either in the sender unit, or the gauge.    On some further research, the sender units fail with the same symptoms I have.

The other possibility is that the oil pressure relief valve is stuck open or partially open and I really have low oil pressure.     The evidence seems to point to the sender unit.     I’ll be ordering one and replacing it as my next step.   The best troubleshooting step would have been to attach a mechanical oil pressure gauge but I don’t have one.

There is never a dull moment with old cars.

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