Finally got the new box of goodies in the other day,and this morning,before
the wife and I go Christmas visiting,I would attempt to replace this known
little irritant.

Spent a little time grinding down a 3/4 inch crowsfoot tool to do the job.

Five min. later,Job Done!
Did not even get dirty!

Merry Christmas everyone!

Jim and Cindy.

 

So Jim did you fit an idiot light or another one of these?

Larry

 

Hey Larry,I fitted another sensor,ordered the wells one from rockauto for around forty bucks.

The original one was still in the car,and hot at idle indicated the pressure was lower than nil.

It should be noted that 20/50 oil was being used.Changed the oil to a more winter friendly 10/40 the other day,and that really made things worse!

The new part fitted the other day now indicates 80 PSI at startup,dropping to a splendid low of 65 PSI at idle hot with said 10/40.

Not too shabby!

There is a port two inches to the right of where the oil press. sensor threads into the block,on the same oil gallery,to fit a pressure guage.

It's hard to get a pic of this,but I will!dammit!and I want to verify actual pressure with guage pressure on the dash.

It might take a resistor in the circuit,but we will get there when we get there.

Besides,it's almost time for the yearly intake muck out anyway,so will take decent pics then.Should be interesting.

Cheers as always
Jim and Cindy

 

Hey Jim, Just ordered a new oil pressure gauge myself, got the BECK/ARNLEY but I'm sure it probably needs a resistor too. Any idea what the oil pressures are supposed to read (avg) with a working OEM Jag unit?

Was thinking I could make up a few resistor connectors in different values and swap em out till the gauge read at the sweet spot?

My pressure sensor has always been on the way out but has recently gone from annoying to completely screwy, now I get the oilcan lit even at highway speeds.

Stop the car for a few minutes and it's sorta works again. Pain in the butt alright!

 

I finally had the stuff off of Champ the other day for It's annual oily-muck-out of the intake tract.I finally got a clear shot of the other pressure port on the engine.Champ's at least.

It's the little grub screw two inches right of the shiny new sensor.

I cannot for the life of me remember what the thread size is...

but I have done an oil press.check awhile ago.
In my view,the new sensor reads high for what actual pressures exist on the oil rail.
I figure the guage should reflect actual pressures,and not some fake value.

I am gonna see if I can find an old potentiometer to temporarily splice in,dial up the correct value in the car,then make up the correct resistance value resistors from that.

I will post the imaginary thread size too

It seems I have too much time on my hands these days...

If you need a hand Larry,I will put the kettle on...


Cheers All as usual,Jim

 

Hey Jim, don't have the sucker in hand just yet but might take you up on the cuppa and maybe use of your ground-down crowsfoot when it gets here - the rheostat/potentiometer route sounds like a plan btw!

When my sensor works (first start up of the day on 20-50) it reads just below 40 [centre] at fast [cold] idle ..about right?

Talk soon mate

cheers

Larry

 

Hey Larry,forty pounds seems low on cold start,but you may find you have a sender,not a sensor.

Either which way,the one you have in there sounds like it's pooched!

Good thing I have the whole set of crowfeet to grind on!

Let us know when your new part arrives,and we can figure it out!

Now all I have to do is find an old volume control out of something and do some slick wiring

Talk soon,Jim.

 

Found this on another forum Jim, maybe of some use?

The JDHT DVD “Engine and tuning data” gives the actual pressures as follows:-

Idle speed....................2.07 Bar (30 PSI) minimum
At 4000 RPM...............4.83 Bar (70 PSI) minimum
The ideal running temperature is between 88 deg Celsius and 96 deg Celsius.

Larry

 

Hey Jim, I just got this info from Casso in the UK regarding the resistor value, and Bob Wilkinson did the translation, giving us 150ohms - so heading over to Queale's tomorrow!!


and

Cheers Jim - Want me to pick up two or do you have one in your kit already?

Larry

 

Wow,you lucky fella!I thought they all went away!
If you are goin shopping,I need everything!haha,I need a variable resistor,and I need the goodies to repair the blower boards in Redd.
Maybe some spare relays too....damm
Sucks up here,not having any kind pf electronic parts house..
I was thinkin I was gonna scavenge a volume control out of an old radio or something.

Whatever you bring will be awesome!
Talk soon,Jim.

 

Ok, PM me the list of parts you need for the blowers, I had to order the bits for mine when I did them,, didn't have them in stock esp the darlington transistors.

What relays do you need? I ended up fitting an external diode to mine for the internal blower relays as the OEM Hellas are pretty spendy items compared to regular relays found elsewhere on the Jag. There's a good thread on doing the outboard diode in the archives on here.

I replaced all of the blue relays in the engine compartment with sealed relay part number 117898 from carpartsdiscount.com, $6.95 each (no affil)

cheers

Larry

 

PM sent!

 

Ok Jim, got you the parts to fix your blower speed control circuits, hopefully all you need, will take a drive up tomorrow (wednesday) morning, see ya then

Larry

 

Well, thanks to Jim's (manwich66) perseverance, the car is now sporting a new oil pressure sensor

The unit is a real PIA to fit on these late cars, the air pump metal plumbing is really in the way, would suggest swapping next time when throttle body etc is off for a service.

Jim managed to replace it from underneath, but without the patience of Job, it would have been a no-go for sure!! As it was, he had to remove the oil filter and the oil cooler bypass fittings to get the (crowsfoot) wrench onto it.

With the throttle body and associated plumbing off the job would have gone quicker I guess, but thanks to Jim, it's done now - AND - I now have true(ish) oil pressure showing on the gauge. I have no idea what the units are btw. [the scale reads from 0 to 8]

Here are the new numbers:
Cold idle 7
Hot idle 3-4
Highway running 6-7

This is without a resistor. At first I fitted the 150 ohm resistor that was recommended, but with this sensor it seems to be unnecessary.

The readings with the resistor were around 3 at cold idle and the gauge hardly went up at all at 2000 rpm. So it seems with THIS sensor, you don't need and resistors.

The sensor I purchased is a Beck-Arnley #2011505 and it was stamped "Made in Spain".

No more oil-can red light on the dash lit up at 70mph ...YEAH!!!

Thanks again Jim and Cindy!! You're the best

cheers

Larry

 

Glad things are working out well,pressure wise.My muscles are sore today so I am relaxing.Will post soon on fitting the resistance value for our 91 cars.Thanks again Larry for bringing those electronic goodies!

Cheers,Jim and Cindy.

 

Any updates Jim? - I still think mine is a reading a tad high ...

Larry

 

Champ car is working so well,I can't seem to get my hands on it long enough to do any more work on it!

Our guage reads a little on the high side too,but I have to convince the wife to let me have another go at it.

Meanwhile,there are other chores to do,but very soon I am gonna jump back on this.....
Cheers,Jim.

 

Jim & Larry,

Any idea of the resistance of the sensor and the resistor combined when the needle in the gauge is centered? I'm seriously considering bypassing my sensor with a resistor to ground. Low oil pressure seems to be so rare in these engines that I'm just not worried about it.

Thanks in advance for any advice,

Cheers,

Don

 

Don, I think we all feel the low oil pressure is almost always a false reading - I was just fed up with it throwing on the oil-can warning light when everything else was working just fine.

Getting the resistance of a centre-reading needle with the analog type of sensors Jim and I have fitted may not be the easiest thing to establish as the reading (resistance) varies quite a bit with the engine revs and temperature. The idiot-light type of sender would be your best bet for measurement if you're looking for a centre reading.

I think Jim has figured out the best way to determine the correct combined resistance value of these aftermarket sensor/resistor combos - he just has to make arrangements with the wife to take the car off the road for a while as explained above!!

Jim's way (which makes perfect sense to me) is to connect an accurate pressure gauge to the second oil access point located just aft of the oil pressure sensor (illustrated above) and take a reading.

Then, using a variable resistor in series with the oil pressure sensor, dial in the resistance until the gauge in the car matches the reading obtained on the pressure gauge connected to the second access point.

Measuring the resistance setting on the variable resistor should then give us the correct value for a static resistor to fit.

The 150 ohm value bandied about on various other threads on this topic is definitely too high - I had one made up and gave it a try when Jim replaced my pressure sensor with the effect that the cold pressure read somewhere around 2-3 bar and hardly moved up at all when the engine revs were up around 3000 rpm, so we ditched it.

Cheers

Larry

 

Hi Larry,

I have the idiot-light sensor fitted, but keeping it reading at all is the challenge. Over the years I've probably replaced the stupid thing three times trying to find a sensor that would either read correctly (the earlier transduscer sensors) or just center the needle (the later idiot switch type). My assumption is that over time oil works its way into the mounting threads of the sensor and interferes with its ground connection, throwing off its reading.

My current thinking is that given how useless the sensor is (unless it's removed and cleaned frequently), I'm tempted to just connect a potentiometer between the wiring harness and ground and sweep it till the needle is centered, then measure the resistance of the pot and substitute a fixed resistor or combination of resistors of the same value. That's why I was asking about the total combined resistance of the sensor (and any added resistor) when the needle is centered.

Cheers,

Don