Lift and Oil pressure questions-99 XJ

Good day ladies and gents! I've been shopping for an XJ for quite a while now and just yesterday a guy came and gave me cash for my truck. Now I've got to seriously start looking for my next rig! I've previously owned a CJ8, 02 TJ, and an 05 Rubi. Now I've got 3 kids and want to get into an XJ

I found a 99 XJ with 166k, the up country and tow packages and have a few questions about it. The owner said it has about 3" of lift and is sitting on 31s. How high can the XJ go before I need to start looking at driveline angles and whatnot? Again, I've got a Wrangler background so I'm somewhat stupid, though learning, when it comes to XJs.

Second question, he sent me a picture of the dash with the Jeep running warmed up (210*) at idle and it shows an oil pressure of about 40. I've read on here that oil pressure is usually around 20 at idle and 40 at speed, is this something to be worried about? Thanks a ton! Best XJ forum I've found on the intertubes!

-H

Oil pressure sending units tend to fail on the high side in that year range. No worries.
At 3" you're good. Any higher, be ready for a SYE.

In terms of the lift, you really need to drive it and see how it does...no two XJ's are alike. I've done 5-6" lifts on late models where they didn't need an SYE or even a tcase drop. I've also done 3" lifts on late models where they needed an SYE at that small of a lift (Mine was like this back in the day when I did my first lift).

As for oil pressure, 20psi HOT is normal. You'll need to drive it for a while to get everything good and warmed up to get that reading though. If you just crank it up and bring it up to idle, it will sit at 40psi for a long time before it starts coming down. 40psi on a 4.0 that's only been warmed up to idle is perfectly normal.

Good choice on a 99...excellent year

I guess what threw me off was that the Jeep was sitting at 210* so I figured it was warmed up enough to where the oil pressure would start dropping to normal operating pressure.

Yeah, to be honest the only year I'm really looking for is a 99. I'd entertain a 98 and MAYBE a 97, and if it was a ridiculous deal 00-01, but 99 is my sweet spot since it'll be a daily driver.

I feel that 99 was the high-point in XJ production.

The 97 was the first year with many changes and reportedly the wiring diagrams for that year are, shall we say, confusing or misleading.

The 97 model year gets a really bad rep here, but mine has been, hands down, the most reliable vehicle I have ever driven. I've had mine for 11 years and put over 150K miles on it. I disagree that the 97 is a basket-case year, even though a lot of people say that. Maybe I'm just lucky, but it's been a great car.

I have a question about the oil pressure. I am reading upwards of 80 when on the throttle and it drops to about 60 at idle. Does that sound like a bad sending unit? I just changed the oil and noticed this. Engine temp is a 210.

Yeah, mine was doing that and eventually pegged at 80 all of the time, a new sensor fixed the issue.

siebermd said:

I have a question about the oil pressure. I am reading upwards of 80 when on the throttle and it drops to about 60 at idle. Does that sound like a bad sending unit? I just changed the oil and noticed this. Engine temp is a 210.

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Sounds like it. What brand of oil filter are using?

hillikus said:

I guess what threw me off was that the Jeep was sitting at 210* so I figured it was warmed up enough to where the oil pressure would start dropping to normal operating pressure. .

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Don't worry about it. Remember that the oil temp is not the same as the coolant temp. Mine takes about 15-20 minutes of highway driving to get the oil up to its normal temp (much longer around town). Verified on aftermarket gauge.

cruiser54 said:

Sounds like it. What brand of oil filter are using?

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Im using a Fram "High Mileage". But I have a sneaky suspicion that "High Mileage" just means an extra couple of $$, how different could it be really?

siebermd said:

Im using a Fram "High Mileage". But I have a sneaky suspicion that "High Mileage" just means an extra couple of $$, how different could it be really?

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Try this. Go to Napa and get a Napa Silver or Gold filter. Silver if you change oi levery 3 to 4000 miles and Gold if you change every 7000 miles.

Remove just your Fram oil filter. Notice how much oil DOESN'T spill out upon removal because it has a crappy anti-drainback valve. Put a little oil on the new oil filter seal and spin it on and tighten it hand tight per the instructions. Start your Jeep, check the oil after it's shut down for about 15 minutes. Top the oil off but you probably won't need to. Drive it for a few days and observe your oil pressure. Is it better?