Oil Pressure Gauge Kit

[Mike Wattam <MikeWattam@domain.elided>]

Hi Henry

I would advise against fitting an oil pressure guage.  Triumph knew what
they were doing when they did not fit this on the Stag, it is only
something more to worry about and the oil pressure is so variable on the
Stag anyway - plus very inaccurate guages - that it is just not worth the
trouble and inconvenience of carving up your dash.

There are those who claim it is telling them vital information about the
engine such as blown bearings, but frankly by the time the oil pressure
guage has responded the bearings are blown  - and this assumes you have one
eye on the guage all the time which of course unless you like having
accidents, you are not anyway!  

Add to that the vagaries of temperature, sticking relief valves, the
different specifications of build including high pressure (Sabb) pumps,
high rate relief valve springs, various specification oils, and the whole
thing is untenable.  My Stag when checked with a master guage ticks over at
15-18psi and under load (hot) at 3,000rpm is 40-45psi.  Is this an
acceptable figure on an engine which has done 100,000 miles and has never
been opened up?  And why did a high pressure relief valve spring make no
difference to the oil pressure?

So, what does low oil pressure actually indicate?  That the bearings are
loose?  Or might the oil pump be worn out?  Or the relief valve sticking?

And if the pressure is high, does that mean that the bearings are perfect? 
Or that the oilways are partially blocked so no oil is getting to the
cylinder heads?

Does the oil pressure guage judge oil flow rates?   And is oil flow rate
important anyway?

I have had a couple of member technical queries this month on this subject.
 One said the guage showed that the oil pressure was very slow to build up
and the other said it was staying high after they turned off the engine -
for 2-5 minutes.  It transpires the screwed sender unit has a very small
'bleed' hole facing the oil pressure, presumably this is small to dampen
out momentary fluctuations in oil pressure inside the engine. This had
become blocked by condensation/oil/corrosion so the guage had effectively
ceased to show the oil pressure.  This would account for the alleged
'sticking relief valve' complaints I have seen in this digest.  Unblocking
the 'bleed' hole is one thing, an obvious thing to do is to increase the
size of the bleed hole but how far you should go I am not sure, but I would
suggest not far but merely to clean the hole out thoroughly.

If a CHEAP kit was available I think I would go for an audible low oil
pressure warning, and that is definitely all.  

I already have a high water temperature warning fitted to my car (not that
it has EVER overheated in 26 years) to allow me to fully enjoy driving the
car.

The Stag is best driven, not worrried about unneccesarily.

Mike Wattam
Chairman - Triumph Stag Register