I know there are quite a few posts on this but the only conclusion seems to be the Jaguar sensor and gauge are garbage.

Since my engine is out I'm doing those things you should do when the engine is out, I recall my oil pressure gauge suffered major lag, responsive it was not.

I've seen some work on the E-Type forums regarding resistances of the sensor, not seen a whole lot about the gauge itself, there is nothing in the service manuals about testing it or the cluster instruments.

Short of removing it and putting a more reliable item in its place has anyone really resolved this issue. I'm tempted to put in a reliable sensor and drive the gauge with an Arduino ... it is a pity instrument clusters are so expensive secondhand or I'd buy one to play with. I really don't want to fill the cabin with non standard stuff - I can be a bit of a purist about such things on my older 'classics' - I don't mind having modern tech behind the scenes but visually it must remain as per factory.

Just wondering if anyone has seen anything interesting in this area, most of the threads never seem to reach a conclusion beyond the Jaguar standard provision sucks (something even Jaguar seem to have figured out but never fixed properly).

 

I just did the research on this as I have a leak from the top of my engine and it's the oil pressure sender. I'm going to replace the sender and the switch this weekend, but I feel like it's likely they will start leaking again in short order.
One thing that I have done in the past is to try to hide a small, mechanical oil pressure gauge in an unobtrusive location, but the XJS doesn't have many of those. I'm just going to replace it and cross my fingers that they work and don't start leaking.

 

It will be fine - eventually! I had to go through a few before I found one that lasted. It is the quality of the part, not the Jaguar system that is the problem.
On the pedestal, there actually is a spare port; but getting the blank unscrewed HAS to be done with the pedestal off the car are VERY carefully supported, or it will shatter. You could, of course, buy one of these (which I have tucked way against the day i can no longer afford petrol and decide to rebuild my engine!).
http://www.rob-beere-racing.co.uk/ne...html#Camfeed12
And no worries about it shattering when you need to change the senders.

 

Ben,

Yep, heard all this before, garbage is a tad harsh, but whatever.

The sender for the oil gauge is a Smiths unit, and YES, flaky from the start. They leaked, and they gave erratic readings.

Specific to the Jag, using "reverse Ohms" (my terminology). Only other car that used that was the Aussie 280ZX Nissan Thing, but even aftermarket has their sensor as NLA, oops.

BUT

The most common issue is the BAD earth circuitry of the cluster, hence the dedicated earth wire added to the cluster, smartens up all of the Instruments.

The Idiot Light sender is just what it is, and they weep, then for no human reason, blow the end out. I have replaced a few, and the Toyota unit is the best, EARLY Corolla, 1970's vintage, was the last one I source in the Aussie Outback, 1/8BSP thread, spade wire terminal, all done in the car park of said dealer in 20 minutes.

Lag, yeh, that's life in the real world.
Since you have the engine OUT, replace the "crappy" o/rings on the oil suction and supply pipes, INSIDE the upper sump. Viton spec is the latest and greatest, and that will sort that issue for your lifetime and the next. If you choose not to do that, the engine will be fine, as my PreHE has not been done and 655000kms still pumps oil as needed.

 

The 'garbage' conclusion wasn't mine but disatisfaction with them is pretty widespread even back to the E-Type days, the conclusion is based on a summary from all the stuff I read yesterday. It is clear Jaguar had no motivation to even attempt a fix (other than the later fake 'switch' one), my complaint with mine is that it is slow, I've no evidence how accurate mine is, not very is my immediate thought.

O rings I need to figure out - are they 'standard' types or Jaguar specials - I did plan to open it all up but to date I've chickened out - I have the gaskets. The oil cooler gets few mentions but mine had some of the nastiest black sludge you have ever seen in it - thick and sticky like grease - I bought a new one but I'm still unable to work out how it gets primed and theres no way it can drain.

I'd seen the Rob Beere things - very expensive and what benefit - I'm only trying to deal with my OCD here - a gauge that is inaccurate / unresponsive / slow will keep my OCD on steroids. I read though that the other gauges aren't so accurate either. I also found some extensive work that was done on the sensors by

I bouught longer banjo bolts for the back of the heads but the holes seem awfull small, not surprised people discuss oil starvation up top if these things aren't 100%. I'll be removing the entire turret and lines and dropping them in the ultrasonic. I found a page that described removing the top of the sensor - they can be calibrated, did a review on other gauges and they were typically 25% out - I'm sure it was over on Jag lovers but it is proving to be elusive. I can figure out resistances using compressed air, using a known range of 0 to 100, I believe the coils on the gauge are 12V not 5, going to spend some time in the wiring diags today.

I'll pull the instrument cluster over the weekend and give it some abuse - I'll be waiting on paint curing in the engine bay anyhow - hope to get basecoat on today and lacquer tomorrow.

Since instrumentation and controls is the skillset I've used for 32 years (time served mechanic prior for 12) I'm considering building an interface between sensors and instruments, I just need to decide if I want to put my instrument cluster at risk - I have tracked down a new old stock gauge from one but even thats expensive. Maybe my 32 years doing instrumentation and control is why I struggle so much with laggy inaccurate sensors, I shall also delve into the pressure switch some. Probably need to suck it up and buy a few for bench assessment all our decent motor factors are gone - the ones we have get lost if you can't quote a registration make and model - which doesn't lend itself to a parts bin rummage. I have a similar issue with my Nissan engined car - the Nissan supplier is clueless because it ain't in a Nissan - it's a CA18ET - just leads to a glazed expression - had to buy gasket sets for that from Atlanta in the US.

Early days yet, I've a number of jobs to do on the engine while it is out.

PPS if anyone has sizes for those O rings on the oil pickup / sump lines it would help considerably. I tried to buy some from Jaguar so I had the sizes (not for use) but they're listed as NLA

 

OK, getting a tad deep there, but,

Oil pressure rise at 1st start that is slow and sluggish is NOT uncommon, and thats how they have all been. Some here have gone to great lengths to address this, and ended up at the same end result.

The o/rings are a well discussed item, and NO I dont know the sizes now. I simply took the old to the bearing supplier and got Viton spec to match.

The gauges in any Jag, or other normal road going car, have never been what one would call accurate, and they were never "spun" to be that. A good guide, yes.

Speedo being the exception obviously, but again so many variables at play with that one.

Never seen oil starvation on the top end, or anywhere else, on a Jag engine.. OK, the V12 is "drier" up top than the old XK engine, where the camcovers were flooded with oil by design. Leave the oil cap off a V12, and run the engine, and you will have a mess in no time.

The longer banjo bolts are a good idea, and I made my own a very long time ago.

The oil cooler, is a nightmare, agreed 100%, as it does not, and cannot drain, no matter how long it sits open. I thought of getting a drain spigot welded into the end tank/s. I moved on, another oil leak place, NAH.

Priming the system is usually via the oil sender hole, and with TIME and patience, it can be done fairly well, never 100%. The oil pump shifts a huge amount of oil very quickly, and at high pressure as soon as the engine rotates. Pre filling the oil filter is always a good thing, which you know anyway.

Jaguars take on oil pressure for the V12 was, ?? @ 3000rpm, and under that, of no concern at all. ?? = I forgot, duh.

My mechanical Master Gauge, very old school, showed 95psi @1200rpm Cold, and 15W40 oil. At operating temp, and @ idle of 800rpm in P, the pressure was 35psi, and @ 1500rpm = 50psi, good enough for me. Duly noted where the OE gauge sat at each measure I wanted. It took a few seconds to get up to pressure, but that how it is.

 

All good to know - I'll avoid too much messing if the community at large haven't managed to resolve and it doesn't really seem that it has, not sure why I'm so concerned none of my other cars have oil pressure gauges, never been a fan of idiot lighhts though - my experience is that it is usually terminal before those things trigger.

I'l just need to treat those gauges as politicians and view with a good pinch of salt - hope the OCD co-operates.

Was hoping not to have the sumps off too long but I've formulated a plan to buy some secondhand pipes etc - I haven't separated engine and box and I'm not sure I plan to so my engine support is kind of redundant - I need to sit with the thought fuel (beer) and figure out a plan.

I'm all in favour of old school

 

Depends on driver reaction time and circumstances at the moment

If the oil pressure gauge suddenly drops is it really that much different than an idiot light suddenly coming on? In either case, if you can kill the engine immediately and pull off the road you can probably prevent any damage. If circumstances dictate you must keep driving for a bit, well.....yikes! Cross your fingers!



Yup!

You can gain some comfort knowing that oiling problems (other than leaks) on a V12 are rare as hen's teeth. I can't remember when, if ever, I've heard of a V12 suffering a failure of the reciprocating assembly for any reason, including failure of the oiling system.

Cheers
DD

 

Leaks - I have one but it isn't from up top - everything under the oil pan, gearbox bell housing plate are soaked but I don't think it is engine oil, I'm poking around before I disturb stuff or clean it off. None of the prime candidates are known leak areas on the Jaguar V12 (rear main or front auto trans) - I think the power steering cooler may have been the culprit though - only think - that side of the engine / sump was soaked - still is - but the oil return hoses (the tiny ones near the filter) weren't in good shape either and I've read a couple of threads where they leaked.

Idiot lights like so many things depend on where your attention is, on my higher performance mutts I have a a buzzer in circuit with them. So much does depend on failure mode anmd where your attention is I agree but on the two occasions I encountered it once in a Nissan 1.8 Turbo and once in a Ford Escort 1.6 both resulted in damage requiring substantial remediation. One was a failed relief valve - heard the clatter before I saw the light, and the other a total loss of oil due to a turbo feed pipe fracture which lead to a spun bearing, I caught the latter but the damage was done, it's a case of by the time you see the light which isn't necessarily when it comes on.

My 'what if' paranoia is probably not warranted but that's me.

 

See if you can find some UV oil dye. It's extremely helpful to pinpoint exactly where leaks are coming from. This picture is from a leak on my V6 converted MGB that looked for all the world was the rear main seal while in the car - except it was from the rear camshaft plate. I won't tell you how many times I replaced the rear main seal before I figured out what was going on.

 

Did this dye require the engine running or is it something you just spray on ? - never encountered the latter - curious and interested. My engine is presently on skates on the floor so running it would involve hassle I'm in no mood for. I'm replacing everything that is a known leak point or problem area from top to bottom following the documentation and wisdom of those with more V12 experience than I have. The only thing I don't fancy getting into is the rope seal at the back of the crank as I don't have the sizing tool (or the inclination though that may change) - this is one of those I think old school is best things - like the rope seals on the wheel hubs. The oil pressure sensor and the manifold it sits on are just one area getting attention whilst it is simple to do.

 

Yeah, it requires the engine to be running. In your situation that sounds not feasible.

 

Thanks, I'll do some digging, think I may still get some - it may help find my screw ups when I get the engine back in, so that when I take it out again I know what I screwed up.

 

Faith Ben, ya gotta have FAITH.

Rear main rope seals on Jags, weep, sometimes. That is mostly on Garage Queens, and similarly low use cars.

Normal, whatever that is these days, used engines dont leak to any point of causing drops or under car spray.

The gallery core plug,, B Bank side, behind the flex plate CAN, RARELY, leak. I have only heard of ONE in all my time, BUT, with the thing out, to not look at that would cause even me sleepless nights.

Ypu mentioned Left side, and maybe steer cooler, good thohjt.

Look at that alloy vent casting on the B bank head front. The bolts are threaded into non-blind holes. I use sealant on the threads, and a copper washer under heads, leak gone forever, and I mean LEAK, they are bloody deceiving on some engines.

 

Looks like I'm splitting engine and box then .... botheration .... every time I look at the car I end up with more parts to trip over, remember when I first started this and said it would be a rolling project not boxes of parts .... think I fell off the path somewhere.

 

These sound like sudden, catastrophic failures. In either case I'm not sure how an oil pressure gauge would've saved the day.

I like the buzzer idea. You're certainly correct about where the driver's attention is focused. I can think of only one time I injured an engine. Coolant hose failed; I was in near-gridlock traffic and my mind was elsewhere. I'm sure the temp gauge was creeping up for a few minutes but I never noticed. When I did notice it was far too late. Thankfully it wasn't a Jag. That would've been a heartbreaker.


Fully understood and appreciated

I'm just musing; no argument or criticism here.

As the years keep rolling past I find myself becoming increasingly less fussy, concerned, and worried about things. And that's just me.

I'm reminded here of my dad. He wasn't very mechanically inclined in a get-your-hands-dirty sense but he was very attuned to the operation of things. A minor noise, vibration, hiccup, roughness...almost anything....would get his attention. I attribute this to his days as a pilot in Uncle Sam's Flying Club ......about a million years ago when airplanes were nowhere near as reliable as they are now.

(Aside: Over the years Dad would bring me his cars for repair with worries that the clutch didn't seem quite right, or there's a slight misfire, or there's an odd shudder, or....or....or this thing or that thing. As often as not I couldn't never see, feel, or hear what he was talking about. I'd return the car to him, untouched, with an explanation of how I reset the mixture and points, a tightened-up the brakes, and secured a loose bracket. He'd call me the next day to say "By gawd, Douglas, the car has never run better!"

I recount this with a combination of both shame and amusement)

Thanks for letting me stroll down memory lane

Cheers
DD