Basic Q&Afor the Newbie XJ owner

Okay, just picked up an 87 Limited (4.0L) from my bro...I know little about the thing but I'm learning quickly. Couple of questions:

1) Went to have it smogged and was told that I failed the "visual" as the check engine light was not operating, though the guy running the test told me he could "forgive" me for it. Thinking the bulb was out, like every other instrument bulb was when I bought the thing, I pulled the dash apart and noted that I did not have a bulb in that place (just like I didn't have bulbs for anti-locking breaks since the Jeep doesn't have ABS). To test, I pulled the bulb out of the low wiper fluid slot and slipped it in to the check engine slot. With the ignition key forward but the engine not running the bulb didn't light up. So the question is: Am I supposed to have a bulb there? If so, what's the issue?

2) What temp is the engine normally supposed to run at?

3) What is the normal oil pressure for the 4.0L. It seems that mine fluctuates quite a bit, with the pressure being "pegged" at 80 while on the freeway.

4) Air conditioner's performance fluctuates on the freeway, and the cruise stopped working...do I have a vacuum leak that would affect both systems?

I did a thread search and really didn't see a lot that helped me specifically, so any suggestions/help are very much welcomed. Thanks all.
Tony in San Jose

1. You don't have a check engine light. Never existed on the Renix system, and don't let them tell you it should have one.
2. Around 210
3. My oil pressure at a hot idle is about 20 PSI, cruising at 65 MPH, RPM~1900 Oil pressure is 50

The Renix era (87-90) XJs & MJs had an "Emissions Maintenance Reminder" light... all this is a light that is activated by a timer. It isn't a "check engine" light as much as it is a reminder to check and/or replace things like the CCV hose 'octopus' the cat, O2 sensor, tune up junk etc...

So, where did you go? I go through that every few months (four RENIX XJ's - and I'm here in San Jose as well.) I always have to explain that the RENIX setup is "pre-OBD," and therefore does not have a "Check Engine" Light.

I've long since removed the timers that drive the "Emissions" lights, and haven't had any trouble as a result. I think it's somewhere near the fuze box - you might want to try searching here (I haven't even seen one in five years or so...)

Normal operation is about 210-215*F, but that can be lowered effectively and without increasing emissions (I think it will actually reduce them slightly...)

You might want to check your oil pressure sender - idle oil pressure should be 12-15psig, and "running" pressure (somewhere around 3Krpm) should be up around 35-40, as I recall. If you need a better number, I can get one.

There is a vacuum reservoir inside the front bumper on the passenger side, that is split between cruise control and HVAC controls. Since all the plenum doors are vacuum-operated, that would explain the A/C difficulty (I'm assuming you'll find that it "defaults" to exhausting through the winscreen vents when it "fails?") The cruise control is also vacuum operated - it's the large servo on the firewall over the engine.

That vacuum reservoir will wear out and leak over time, and want replacing. Getting a new one (I don't know what they go for) should solve both problems.

It might be useful to check the Nylon vacuum lines for engine management for leaks - about once a year. Replacements can be had at NAPA on South Winchester (they'll have them about 3 days after you order them) for $50-60 the set.

5-90

What do you have for mileage? Im a little surprised your Check Emiss light isnt on. Maybe its (the timer) already unplugged? Or the timer has already been renoved.

For the smog I actually went to a place in Santa Clara on the El Camino. Seems that since my bro let the tags expire for a few years, I had to go to a SMOG only station and do the rolling smog test. The Jeep has about 196K miles on it.

1) So if I've got this straight, no check engine light but rather it's a service light on a timer? Guess I have to see if it's been disconnected then? Where is the timmer located at behind the dash?

2) My temp seems to be somewhere around 180 or 190...hmmm?

3) Oil pressure sender can't be that expensive so I guess I should just swap that out and see what happens.

4) Okay, I'll look for the vacuum reservoir and check the hoses and see where that leads me.


NAPA on Winchester...hey, that's like 3 blocks from me. Small world my friend.

Tony

Geez - I'm at 85 & Camden...

Sounds like you went to Greenslip. I had to take my 88 there when I got it, because I bought it in Scrappymento (and the smog test is done by where it WAS registered. Not by where it WILL BE registered. Damn...) I ended up yelling at the guy doing the test and his boss because he managed to stall my engine (it's a five-speed) on a LOOSE dyno!

I've been telling them that I've got an experimental AWD mod now, and I therefore still do the idle test. I just don't trust them to drive my truck, even on rollers.

Having an engine temp down around 180-190 isn't a problem - that's where I try to run (actually, 190-195 - but close enough.) Like I said, it's possible to reduce operating temperature somewhat, with no ill effects.

The vacuum hoses are under the battery - if it's had a leaking battery, then the hoses may be suspect. Elsewise, get ready to change the "bubble". NAPA may have that under their Echlin brand as well - I haven't checked yet. I'll be making a new one out of metal when I have to replace the thing.

Oil pressure sender shouldn't be too bad - make sure you get the right one (specify LIGHT or GAGE) and you'll find it installed down by the base of the distributor. It may require a funky socket to take off - I have one. Apply sealer SPARINGLY - it's a self-grounding sensor, and needs to ground out through the threads (light PTFE pipe dope or RTV Copper will both work well.)

A dedicated smog shop should be able to see (somewhere in a book) that XJ's weren't OBD-compliant until 1991 - so I'd not go there again, if it can be helped. There's a "Test Only" shop on Camden that does a little better - Smog Doctors on Camden, I think they're between Bascom and Union. You'll definitely have to cross under 17 to get there.

Anything else?

5-90

Thanks for the help. Looks like I've got some "home work" this weekend.
Tony