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View Full Version : 99 XJ Sport - Oil Pressure Dropping / Check Guages


reeldba
October 24th, 2017, 18:56
Hi fellow XJ folks. I have a '99 XJ Sport. Recently, at idle, the oil pressure has been falling off to zero, until I tap the gas.

I am assuming the head isn't cracked. I can't decide if the sensor is going bad or if the oil pump is going.

I was thinking that the right way to attack this is to get a manual oil pressure gauge first and verify that the pressure is in fact falling off.

Based on that, I would know if the sensor is the likely culprit or the oil pump.

Make sense?

Thanks!

RCP Phx
October 24th, 2017, 21:34
The most common reason would be the cam bearings, the oil pump doesn't usually cause problems!

Green Mesa XJ
October 25th, 2017, 10:38
Verify the pressure because sending units fail pretty regularly.

Cam bearings can be a culprit, it would not be a common failing, sender, main bearings, bad oil filter, clogged oil pick up screen are more common. Bad oil pump can happen just donít read about too many these situations being solved by a new oil pump.


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Green Mesa XJ
October 25th, 2017, 10:40
Does you engine make loud clattering noises at 0 oil pressure? If not then you actually have enough oil pressure to run the engine. Could still be too low, definitely test it mechanically


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md21722
October 26th, 2017, 06:57
I would verify the oil pressure with a gauge.

lawsoncl
October 27th, 2017, 13:48
Hi fellow XJ folks. I have a '99 XJ Sport. Recently, at idle, the oil pressure has been falling off to zero, until I tap the gas.

I am assuming the head isn't cracked. I can't decide if the sensor is going bad or if the oil pump is going.

I was thinking that the right way to attack this is to get a manual oil pressure gauge first and verify that the pressure is in fact falling off.

Based on that, I would know if the sensor is the likely culprit or the oil pump.

Make sense?

Thanks!

Sounds like a plan. It's pretty common for the sensor to go bad and become erratic like that.

reeldba
October 27th, 2017, 20:46
Does you engine make loud clattering noises at 0 oil pressure? If not then you actually have enough oil pressure to run the engine. Could still be too low, definitely test it mechanically


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Not really. Which is why I was thinking more along the lines of a faulty sending unit. Thanks for the response!

reeldba
October 27th, 2017, 20:48
Thanks! I plan to find a mechanical gauge / tester this weekend.

reeldba
October 27th, 2017, 20:52
Verify the pressure because sending units fail pretty regularly.

Cam bearings can be a culprit, it would not be a common failing, sender, main bearings, bad oil filter, clogged oil pick up screen are more common. Bad oil pump can happen just donít read about too many these situations being solved by a new oil pump.


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Thanks for the response. I'll be looking for a pressure gauge to test with and I'll probably wind up replacing the sender this weekend.

old_man
October 27th, 2017, 23:22
What weight oil are you running?

If you are running a Fram oil filter, throw it out and put in a WIX.

4x4JeePmaNthINg
October 28th, 2017, 08:00
x2 for everyone above, also i recommend an oem sending unit. i to have a 99 and have had 2 napa and one AZ which all failed, they all read a bit odd to. replaced with a new oem and it reads as it should following your RPMs. also the wix is a good filter. i run purolator, just dont cheap the filter, fram are proven crap if your running one.
just my op/ 2cents :D