As a recap, my 1986 300SE started showing low oil pressure. I tried changing the oil and filter, replaced the sender and checked with a mechanical gauge. Still low oil pressure. I decided to do some final oil pressure troubleshooting before I took it into a mechanic to lift the engine and remove the sump.
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.
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