My jag seems to have an oil pressure issue once warmed up fully. 20 mins consitent driving.

The car will not hold oil pressure at all below 1300 rpm aka at idle or extreem deceleration.

Ive read the other thread recently posted that seems to be the same affects of the issue but none of the solutions in it have worked for me.

Sorry writing this in a hurry will check back later.

 

Hi JagNewbie,

It sounds like it could be an oil pressure sending unit. I had a similar problem when I had a 90 XJ40. The gauge would fluctuate between normal and almost nothing. Recommend you have it checked out though with a Jag dealer or Jag technician specialist. If it's a sending unit it should run around $100 or so.

Mike

 

newbie, how many miles on the motor? It can be a number of things causing this. It can be something as simple as the oil pressure sending unit is going bad (can be verified by connecting a mechanical gauge and verifying proper oil pressure). But, if that isn't it, then you are looking at serious work as the other possible problems result in motor work because you are now having to deal with bearings and valves that have not been getting proper lubrication. Your low oil pressure can be caused by a worn oil pump, using too thin of an oil, or a bad main bearing (allows too much oil to flow through it, dropping the whole oil system pressure).

Without a lot of hands on with the engine, this will be a hard one to diagnose. maybe someone a bit more familiar with your model car will have something a bit more specific.

 

If there is anyone who follows me around reading my posts, they have noticed something: I rarely ever post anything about X Types or S Types, because I don't know a darn thing about them. The only thing I can offer those folks who aren't getting any other help is with generalized information, and it is clearly explained as such.

An AJ6 engine (XJ40) will have a legitimate oil pressure problem in maybe one of a thousand cases, so long as it isn't like three quarts low. Carelm is exactly correct.

The original oil pressure transmitters (oil senders) were Smiths, and every one failed at least intermittantly. Jaguar freaked, and directed the use of the 4.2/ 5.3 oil pressure transmitter as a substitute: this left the flourobar gauge in the 1988/ 1989 cars reading maximum nearly all the time, but at least the customer wasn't seeing a red light and thinking his engine was ready to lock up.

Next was a VDO transmitter that worked OK for a while, but eventually would show the same sort of false intermittant readings on the flourobar and the later analogue gauges (1990-1994).

The latest and greatest factory trick was to install a simple oil pressure sender in its place, which is also supplied with a short resistor lead (somebody can correct me on this, I always presumed it was a resistor but never checked). This is an on/ off switch that now yeilds a "dummy" gauge, so the reading you get is right in the median range all the time you have anything above like 7 PSI.

The last version is probably the best way to go, since it is most reliable (also cheaper) and there is no need to worry about a lubrication system fault on this engine. Make sure you are using 20W50 in warm climate,
10W40 for New Jersey winters, and keep an eye on the level until you access the consumption rate. A 1994 XJ6 likes to suck oil past the valve seals, blowing a cloud of smoke on startup and consequently consuming a bit more than normal, which is very little.

Newbie, glad to hear my first suggestions about the fuseboxes were correct, as was the way you bypassed them. Get back to me with the list, and we'll get everything else sorted out in short order. I'd be glad to photocopy the 1993 Product Quality Update bulletin pages about the waterprofing tricks and throw it in the box.

 

Ok sorry for not getting back to this this. this week has been realy busy.

First thing i did when i got the car was a oil change to 20-50 as i saw the car still had a winter 15-40 in it.

Oil pressure culprit was a crap sending unit. I used a mech gauge and went for a 2 hour joy ride and the pressure was rock solid.

JagTech Funny that you mention the valve seals allowing oil past. I picked up a head yesterday for $75 for the porpuse of redoing the seats and seals due to that quick cloud of smoke. Also i actualy got my hands on 2 fuse panels. One is known bad and one hasnt been tested yet. Thesse are actualy pretty simple repairs if your good with a quality iron. The weather tighting of them should be fairly simple.

This weekend i will be removing fenders and handleing any and all water entrance spots.

I will have a full list of parts for you by sunday JagTech. This weekend is dedicated to the Jag.