[xj40] Cant take the pressure!

XJ40
1

Hi Guys,

Yesterday we managed to get the �Check Engine� light off from of
the dashboard of the 1991 XJ6 via re-setting the computer. Today
all was well and all lights were out until we sat at the traffic
lights and I noticed we had zero oil pressure and the oil light was
on.

BUGGER! We drove to the nearest fuel station to check things out,
as soon as we pulled away from the lights, the oil pressure gauge
rose and full pressure resumed until we stopped and we had zero
pressure again, and the oil light came back on. The sixty-mile
journey home gave us no trouble and full pressure, obviously until
stopping again. In a nut shell the oil pressure gauge is acting
like a rev counter!

There is NO oil leak and the engine has a healthy amount of oil in
it. Is it the oil pressure switch or the pump or other?–
Christian Pugh & New Family Member , Our 1991 62K XJ6)
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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2

Hi Christian,

Your oil pressure sender is going south. It’s funny, but even if you have
been reading the XJ40 list for years and years and know that this happens to
everybody sooner or later, it still makes your heart stop to see zero on the
oil pressure gage.

This problem is so common that Jaguar makes a new-style replacement unit
that is actually a glorified idiot light, and if you want to replace your
worn-out oil sender with a real one that actually has some sort of
correlation with oil pressure you will have to shop around to find one.
It’s sort of up to you what you want to do. If you are a purist you will
want the genuine article even knowing that it’s not going to last forever.

Meanwhile, you can put your car in Neutral when you are stopped and that
will make the needle move a little bit so that you feel better.

We took one of these things apart once to see what the failure mode was and
what happens is that the resistor film on the potentiometer gets worn away
in the spot corresponding to the oil pressure at idle.

So don’t worry, the odds that there is really something wrong with your oil
pressure are exceedingly low.

Pat Lokensgard

-----Original Message-----
From: Christian Pugh

Yesterday we managed to get the �Check Engine� light off from of
the dashboard of the 1991 XJ6 via re-setting the computer. Today
all was well and all lights were out until we sat at the traffic
lights and I noticed we had zero oil pressure and the oil light was
on.

BUGGER! We drove to the nearest fuel station to check things out,
as soon as we pulled away from the lights, the oil pressure gauge
rose and full pressure resumed until we stopped and we had zero
pressure again, and the oil light came back on. The sixty-mile
journey home gave us no trouble and full pressure, obviously until
stopping again. In a nut shell the oil pressure gauge is acting
like a rev counter!

There is NO oil leak and the engine has a healthy amount of oil in
it. Is it the oil pressure switch or the pump or other?

Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !

3

In reply to a message from Pat Lokensgard sent Sun 7 Aug 2005:

Thanks for the info Pat. Would you belive I’ve just gone out to get
a bottle of wine (or two) and the fault has gone! Fancy that, who
would have thought it from a Jaguar :O)–
Christian Pugh & New Family Member , Our 1991 62K XJ6)
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !