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XJ 4.0 sounds like a diesel at idle

12K views 10 replies 10 participants last post by  Rasta Monsta 
#1 ·
At idle, my 90 XJ sounds like a deisel and the oil pressure is about 20. When I rev it up the "deisel" seems to get quiet and oil pressure goes up to around 50. This XJ has approx 226k miles. Does this mean its time to rebuild?

bill
 
#2 ·
biohazardbill said:
At idle, my 90 XJ sounds like a deisel and the oil pressure is about 20. When I rev it up the "deisel" seems to get quiet and oil pressure goes up to around 50. This XJ has approx 226k miles. Does this mean its time to rebuild?

bill
mine is a 2000 and has 66k miles... and mine has sounded like a diesel at idle ever since i've had it.
 
#3 ·
It might just be loud exhaust. Pretty much every xj cracks it's stock exhaust manifold.
 
#4 ·
Nature of the beast, especially when cold.

Excessive noise may be coming from the valves, but it's really nothing to worry about. I'd be more concerned if there was a really distinct, intermittant sound that rises above all the others. That can be a sign of something like a lifter tapping. The weight of your oil can also effect something like that.

Good Luck, :thumbsup:

Peter
 
#6 ·
My 01 sounds like a diesel whenever I am at idle and I wouldn't have it any other way. I think it is part of the charm of the vehicle pulling up at a stoplight next to a ricer with an exhaust that sounds like it has diarrhea and my XJ is grumbling like a tractor out of hell. I wouldn't worry about it if it is just the usual 4.0 noises.
 
#8 ·
I think it's a HO thing. My daughter's 94 GC with rare six cyl did it from day one. I remember noticing it the day they picked it up. My son's 89 non ho is quiet as a church mouse and my 96 HO is noisey. I agree it's "normal" even though I don't like that type of thinking. :(

JoBo
 
#9 ·
My '88 now has 243K on the clock and has had that same noise at idle since I bought it with 123K on it. It's quiet when cold, but when it warms up a little, the noise starts. I've tried different brands and weights of oil, which doesn't seem to make too much difference.

I just turn up the stereo and it goes away... :thumbsup:
 
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