Pray for her. She's so pretty. So far she's got 650 miles on her.

 

If a tensioner is causing the problem, you will have a rattle from the chain when you start the engine. It is possible that something is blocking the oil pickup screen. Removing the pan to check is not all that difficult.

 

I'm not really getting much if any noise at start up, not a rattle, more of a tapping sound, not too loud, and I can make it stop 'at will' by hitting the throttle a bit. The tap usually happens when engine is cold. As stated above, the car has over 650 miles since first low pressure warning, BUT this tapping stuff has been going on for over 10,000.

 

It's probably not the pick up tube (will check next) because pressure is very good at high rpm.

 

Could be the 'situation' is grade/inertia sensitive as well as temperature. Seems like braking causes (contributes) and grade (uphill, 5% or more) lessons it. Might be tube related afterall, the dealer tech's opinion notwithstanding.

 

I'm a gambler. So far 700 miles no engine failure, from AC to NYC today. Put a little Lucas in her which did not seem to impress. Same situation: 5 psi minimum at idle which trips the new sensor just like the old one. 85 mph on the NJTP no problem.

 

1/2 bottle of Lucas Oil Stabilizer added Friday, and today, the low pressure warnings were just about gone. Engine continues to operate perfectly.

 

I have a similar issue. I had the sending unit changed out using a genuinie Jaguar part. no aftermarket. Had ol changed and all was fine. Suddenly the oil pressure guage is doing the same thing. After running for quite a while I stop at a light and the guage starts to get twitchy. Up down up down then down to where the light comes on. Engine sounds fine rev engine a hair and its back to normal. Then a while goes by and it does it again. I suspect something in the harness. oil level is fine no noises. Had my tensioners replaced and discussed this with my mechanic. He's confident nothing fell in the pan. Suspects the wiring. I will update when I go by his shop and see what he finds. Hope it's nothing big like lower bearings. Ugh!!!! Let it be a funky wire. Motor has 103K on her.

 

I'm not kidding myself, I know there's something wrong with the engine itself because low oil pressure (5 psi) was measured at the Jaguar Dealership with a presumably accurate mechnical gauge. Lucas is only disguising the issue. It's a "guessing game" what's truly wrong, but I'll play:
Oil Pump? No. Pressure is fine at high rpm and car is still running fine, 900 miles later.
Pump PRV? No, because why design a part to cause this much pressure loss at idle even if partly stuck open?
Sender? No. It was replaced, and mechanical gauge has ruled out all false positive readings including wiring and ECM.
Oil bleeding from cracked tensioner body?
Maybe, but there are no syptoms other than lower pressure.
Next step, drop the oil pan and look for causes there, and remove valve covers to inspect tensioners.

 

First off, you are headed for a likely engine disaster if you still have the old secondary tensioners in that '97.

Second, as the plastic cracks on the old tensioners and chain guides, it tends to clog the oil sump with plastic debris. This is a common cause of low oil pressure on these cars (even after the tensioners/guides are replaced since the debris remains), especially at start-up. Drop the oil pan and inspect the sump and clean as necessary.

 

Thank you WhiteXKR for your helpful response.

I don't know which generation of tensioners are in this engine. Could be the original, but I don't know. As for the low oil pressure at idle and fully warmed up, it never manifests itself at cold start up, only after the engine (and oil) are shall we say 'hot'-- then at idle, the low pressure (5 psi) is there. (With the Lucas in there now, it must be at least 6 or 7 psi since the pressure switch is not lighting the warnings.)

The Dealership mechanic told me that even if the tensioners are damaged and debris is found in the sump, AND he replaced the tensioners, there is no guarantee this will solve the oil pressure situation because it could be worn bearings. Furthermore he said, if no debris is found, especially tensioner debris, and no cracks are visible on the tensioner body, then that pretty much means worn bearings and an engine replacement.

So I am proceeding cautiously.

Could be I need a whole new car. But first, I intend to do as you suggest, and drop the pan, then open the valve covers to inspect the tensioners.

 

Actually ignore my mention of start-up...I had a brain fart.... low pressure would typically manifest with hot oil at idle as you see.

Your go slow approach makes sense.

 

A quick update. I noticed that each time my oil pressure light comes on the cars idle drops somewhere around 600 maybe a little less. when she smooths out at around 750 rpms in drive of course no issues. Dropping off to my mechanic this week. He will check the pressure with a mechanical guage and see whats up with the idle being slightly off. My main concrn like all of you is a major issue in the lower end if this motor. I asked my mechanic again about the pickup being clogged but he stil feels thats not the case. He did change my tensioners last month with the new gens so I feel confident no issues there. I will let you all know soon what he finds.

 

convgto69,


My first car was a 72 Impala convertible, dark blue with a white top and black interior, big block 400 V8 and turbo 400 automatic transmission. Added a high-lift "fireball" cam-- but I digress . . .


Very interesting that our cars have similar symptoms despite yours having the tensioners done, while as far as I know mine has not. It's even true that my mechanic also doubts there are any problems inside my oil pan or pickup (his money is on a cracked tensioner body) but that remains to be seen.


If it turns out to be worn bearings, is that the end of kitty? Not necessarily, from what I understand, engines don't need much oil pressure at idle, all they need is an oil film. I would be inclined to change the oil to 20/50, add a Lucas or two, and subtract one of her nine lives.

 

Another thought is that since the temp gauge is just a warning light in disguise, the engine could be running very warm which could cause a low oil pressure problem at idle. Connect a scanner and drive the car and watch the real temperature when it is warm. If you don't have a scanner, you can buy a wireless adapter and then download an app to your phone to read it.

Brett

 

Does one sender feed both the light and the gauge. Please tell me yes :-)
My 1994 VP 4.0 has the same symptoms as you describe. The pressure appears to be fine above an idle. The car only has 68,000 miles on it so I'm thinking that bearings wouldn't be high on the list of suspected items. I've also noticed that if the A/C is running (which in Phoenix is about 8 months a year), that the oil pressure symptom shows up more consistently. If the ac isn't on then the pressure gets a bit low but the light never comes on.

 

I came across this post on another forum. This makes some sense to me but low oil pressure could lead to such expensive consequences, I intend to resolve the problem quickly.
http://www.xj40.com/viewtopic.php?f=23&t=4320

Best Regards,
Doug

 

Doug,
I finally resolved my low oil pressure problem. Sadly , it was the lower end (104K on motor). I had my mechanic pull the pan to check the oil pump for any blockage. None. Also before that, we ruled out the sensor since I replaced it with a new Jaguar sensor not aftermarket. Also we tested the pressure with a mechanical guage and found only 5 lbs of pressure at an idle. With that, down came the pan. The motor still sounded great , no knocks or any noise that could indicate a bad issue. We pulled one of the rod caps and inspected the crank journal and bearing. The crank looked perfect. the bearing showed wear with just enough to cause the oil pressure to drop when hot. So, we examined all the rod journals as well as the main bearings. Crank was still looking great but all the bearings had similar wear. That was it then. I had my mechanic replace all the bearings and oil pump. He has 30 years of experience and felt confident this was the right thing to do. I agreed. I also replaced the oil pump. Car now has 20 lbs of oil pressure at idle , runs as smooth as before and sounds great. This was not a cheap fix but I feel it was the right thing for my Jag. So my lower end of the motor has 0 miles on it now and my tensioners which I replaced last year have maybe 2K on them. I wish I could tell you it was an easy fix but I can't. Being a muscle car guy all my life and working on chevy and pontiac engines I knew it would end up like this. I got lucky that the crank was not harmed. Hope this helps you and the other members on the forum. Case closed.