[xj] Oil Pressure Conundrum

1985 xj6…oil pressure is reading higher than usual (usually reads 40 psi)
at the mark between 40 and 80, yet the oil warning light is on which
indicates low oil pressure. Any ideas? Or, put another way, where do I go
from here?

Ken===================================================
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Ken,
Identify which pressure switch operates the light. Remove it, and if you
can come up with the necessary adapters, hook up an ordinary pressure gauge
in its place. If it reads about the same as the one in the dash, get a new
pressure switch.

If you can’t find any adapters, get a new pressure switch.

A look through the archives should yield the electrical parameters, if you
want to test the transducer output.

BTW, a pressure gauge is a pressure gauge. It doesn’t have to say “oil” on
the face. Never, never use one for this job that says “oxygen.”

Gene McGough
XJ6C II 1976
XK-150 FHC S834515DN

1985 xj6…oil pressure is reading higher than usual (usually reads 40
psi)
at the mark between 40 and 80, yet the oil warning light is on which
indicates low oil pressure. Any ideas? Or, put another way, where do I
go----- Original Message -----
From: “Ken Weimer” kweimer@bellsouth.net
from here?

Ken

===================================================
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Ken Weimer wrote:

1985 xj6…oil pressure is reading higher than usual (usually reads 40
psi) at the mark between 40 and 80, yet the oil warning light is on
which indicates low oil pressure. Any ideas? Or, put another way,
where do I go from here?

First you check the oil level, Ken…:slight_smile:

Simultaneous faults in both indicators are very rare - and both circuits
are independant. The most likely fault on the warning light circuit is a
shorted wire from/at the oil pressure switch - or the wire has jumped
off and is grounded. This is a pure ‘switch’ function - it’s either
grounded without oil pressure or it is not. And if the latter switch is
either defective or you have indeed no oil pressure - which seems
unlikely…:slight_smile:

The high reading of the oil gauge, may be a faulty gauge or oil
presssure transmitter - more likely the latter, and only measuring with
an independant gauge may tell what pressure you really have. Excessive
oil pressure should really be pursued - blocked oil lines may cause it,
however seldom it occurs…

Frank
xj6 85 Sov Europe (UK/NZ)===================================================
The archives and FAQ will answer many queries on the XJ series…
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In reply to a message from Frank Andersen sent Fri 8 Jun 2007:

I was wondering.
If the oil pressure relief valve has stuck in the closed or
partialy closed position, and the higher than normal pressure has
caused the warning light switch to fail, it would result in
simultaneous faults in the independant circuits…

Dave–
The original message included these comments:

Ken Weimer wrote:

1985 xj6…oil pressure is reading higher than usual (usually reads 40
psi) at the mark between 40 and 80, yet the oil warning light is on
which indicates low oil pressure. Any ideas? Or, put another way,
where do I go from here?
Simultaneous faults in both indicators are very rare - and both circuits


Dave Collishaw Peterborough UK '79 S2 Daimler Sov '92 xj40
Peterborough, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

===================================================
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sparx wrote:

In reply to a message from Frank Andersen sent Fri 8 Jun 2007:

I was wondering.
If the oil pressure relief valve has stuck in the closed or
partialy closed position, and the higher than normal pressure has
caused the warning light switch to fail, it would result in
simultaneous faults in the independant circuits…

Hm, Dave…

The relief valve is designed to open at some 65 psi to bleed oil back
into the sump. As such it is normally ‘closed’ and a failure of it will
show up as oil pressures beyond relief pressure. Whether such excessive
pressure will damage the transmitter and switch, and do it on both
simultaneously, is highly conjectural, and given the construction of the
items highly unlikely…

But the point is well taken and it can only be verified by using and
external gauge to verify actual pressures. At which stage; if the relief
valve proves faulty, it is a fault in itself, of course - irrespective
of its effect on the sensors, so…

Frank
xj6 85 Sov Europe (UK/NZ)>The original message included these comments:

Ken Weimer wrote:

1985 xj6…oil pressure is reading higher than usual (usually reads 40
psi) at the mark between 40 and 80, yet the oil warning light is on
which indicates low oil pressure.

===================================================
The archives and FAQ will answer many queries on the XJ series…
FAQs: http://www.jag-lovers.org/xjlovers/xjfaq/index.html
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