Panhard oil light piston wear update

The original oil light was a machined cast lump…

standard oil light piston

so I created this replacement in mild steel. This is the basic part, because I hand finish this further.

revised oil light piston

This is used with other mods to refine the Panhard oil lubrication circuits. The nose was rounded in the picture below to prevent wearing out the wooden plug that pushes the oil light contact, once the engine gets up to pressure.

I happened to be stripping an engine to use in my EFI project, and I came across this, which was an earlier prototype 1990’s part that I fitted to an engine in 2002, and because I was relying on splash and bleeding from the oil ways nearby, it didn’t need the cross drilling.

rounded oil light piston

Interestingly, there is no wear to the wooden block below, and additionally there is no cross drilling to increase the oil supply to the camshaft timing gears this version, whereas there was in later engines I built. One of the reasons for examining this, was the owner said the camshaft gear was noisier than he remembered previously, and although the aluminium gear is when compared against the OEM fibre wheel, I’d thought I’d investigate further.


Picture above shows the oil light insulator button from inside the camshaft timing gear case, which acts an insulator and breaks the brass contact for the dash mounted low oil pressure warning light earth loop, but only as the oil pressure in the hollow camshaft gallery builds up.
It’s more remarkable, because this particular engine had very little additional lubrication, other than a little splash bleed from nearby oil galleries, and was the first one where I altered the crankcase lubrication circuits.

This is great news, as I now don’t need to do the brass nosing mod, as shown below, which I did in 2004.

one off oil light piston

close up

This was done to an earlier engine rebuild for a two bladed fan Dyna engine, because I was concerned about the potential friction that the hollow threaded tip of the piston might create.


This is the later revision to the oil light circuit, and although it’s incomplete, you can see there is a cross drilling that is exposed once the oil pressure builds up in the camshaft gallery. The relief valve can be set, so that the first priority is the crankshaft big end rollers, and the hole size can be varied if more lubrication is needed to these timing gears. However, as this oil feed is off the central oil gallery within the camshaft, there is no pressure fluctuations as the camshaft rotates to either big end bearing, so eliminating all the developmental faults that were introduced as the years went by.