greetings fellow cat-can-do's, it's been a long time!! new problem with my 1998 xj8, aj26w/109k mi. low oil pressure at idle only. thought i might try oil change w/heavier oil viscosity. any suggestions? currently using 10-w-40. never needed anything thicker since i live in a very moderate location.(vancouver wa.usa.) has anyone come across this situation and if so, what were your solutions and what should i be concerned about? thanks for your time and suggestions!! johnny screwdriver.

 

Well first off Johny before you start panicking.;o))
What makes you believe you have low oil pressure, does dash light stay lit?
MIL light logged a code?
Have you checked ther actual oil pressure with a proper analogue gauge attached to sender port down at oil filter housing?
Could be a dodgy sensor which is screwed into casing near oil filter.
Check the wiring and connector.
This engine should not need a heavier weight oil.
Is the engine consuming oil?
A 4.0 litre should normally use 5W40 or slightly warmer weather 10W50 full syn.
It could be oil pump wear but it's not common.
Check your 'real' oil pressure first.
You should get a maximum of around 65 psi (4.5 bar) at 3000rpm
The pressure control switch should operate between
0.15 to 0.41 bar (2.17 - 5.94 psi). at idle.

 

thanx,xjay8!! i havent really dug in to this issue yet. but to answer your question,it all started with the dash reading "low oil pressure" with both red/yellow warning lights and a red stop engine light coming on at idle when in gear.(like at a stop light) the oil level is normal and appears to be clean.(last serviced approx. 3100 mi. ago) the car does not burn/use oil. i am changing oil/filter today and will also test pressure at sending unit port. thanx again for your info,recommendations,and time. john.

 

Has your car had tensioners and chain guides upgraded? Bits of plastic as these deteriorate can break off and clog the oil sump.

Additionally if you have not at least replaced your secondary tensioners your engine is on borrowed time.

 

whitexkr,thank you for your reply. yes, i have done a complete upgrade on my tensioners,chains and guide rails last fall. what i have done is changed the oil/filter and cleaned the connector on the o/p sending unit. this seems to have cured to problem to date. thanks to all of you jagheads that have assisted me in the past. now i seem to have a problem with my windshield wipers running on/off at random. i have not started to dig into it yet. any info would help. thanx again johnny.

 

There's a microswitch in the wiper assembly under the silicon sealed wiring that can fail leading to random function. If you clean replace and re-seal this you should cure it.

There's another possibility of failure of the wiring around the stalk too.

 

thanks sean b, when you say "wiper assembly" are you refering to the wiper motor? can this microswitch be purchased separatly? sounds like it might be easier/faster to just change the motor. please advise. thanks, johnny.

 

You've obviously not attempted to change the wiper motor assembly Johnnie! - that is a difficult job as the engine and bracket on bracket bulkhead parts are in the way...

The micro switch can be purchased from Radioshack. There's various how to's on the uk jaguar forum if I recall. Not attempted myself, but recall the fix, hope this helps.